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Tuning Physical Properties of GelMA Hydrogels through Microarchitecture for Engineering Osteoid Tissue
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  • Ewa Walejewska*
    Ewa Walejewska
    Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
    Centre for Advanced Materials and Technologies CEZAMAT, Warsaw University of Technology, Poleczki 19, Warsaw 02-822, Poland
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0003-2803-4870
  • Ferry P. W. Melchels
    Ferry P. W. Melchels
    Future Industries Institute, University of South Australia, Adelaide, South Australia 5095, Australia
    Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, Scotland
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    Orcidhttps://orcid.org/0000-0002-5881-837X
  • Alessia Paradiso
    Alessia Paradiso
    Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
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  • Andrew McCormack
    Andrew McCormack
    Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, Scotland
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  • Karol Szlazak
    Karol Szlazak
    Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
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  • Alicja Olszewska
    Alicja Olszewska
    Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
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  • Michal Srebrzynski
    Michal Srebrzynski
    Department of Transplantology and Central Tissue Bank, Medical University of Warsaw, Chalubinskiego 5, Warsaw 02-004, Poland
    National Centre for Tissue and Cell Banking, Chalubinskiego 5, Warsaw 02-004, Poland
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  • Wojciech Swieszkowski*
    Wojciech Swieszkowski
    Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
    *Email: [email protected]
    More by Wojciech Swieszkowski
    Orcidhttps://orcid.org/0000-0003-4216-9974
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Biomacromolecules

Cite this: Biomacromolecules 2024, 25, 1, 188–199
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https://doi.org/10.1021/acs.biomac.3c00909
Published December 16, 2023

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Abstract

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Gelatin methacryloyl (GelMA) hydrogels have gained significant attention due to their biocompatibility and tunable properties. Here, a new approach to engineer GelMA-based matrices to mimic the osteoid matrix is provided. Two cross-linking methods were employed to mimic the tissue stiffness: standard cross-linking (SC) based on visible light exposure (VL) and dual cross-linking (DC) involving physical gelation, followed by VL. It was demonstrated that by reducing the GelMA concentration from 10% (G10) to 5% (G5), the dual-cross-linked G5 achieved a compressive modulus of ∼17 kPa and showed the ability to support bone formation, as evidenced by alkaline phosphatase detection over 3 weeks of incubation in osteogenic medium. Moreover, incorporating poly(ethylene) oxide (PEO) into the G5 and G10 samples was found to hinder the fabrication of highly porous hydrogels, leading to compromised cell survival and reduced osteogenic differentiation, as a consequence of incomplete PEO removal.

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1. Introduction

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Bone is a unique environment that might be described as a composite material consisting of various types and levels of tissue organization. Its complexity is imposed on its ability to self-renew (bone marrow presence) in bone remodeling (BR), during which tightly related events and cell signaling pathways are distinguished. (1) BR provides the microenvironment that links its two major stages─bone resorption and formation (2,3) The knowledge of this mutual regulation and the approaches undertaken to recreate it remains a hot topic in regenerative medicine and tissue engineering.
In this frame, bone tissue engineering (BTE) aims to develop novel strategies for the regeneration of bone tissue using the combination of (bio)materials science, engineering strategies, and cell biology (4,5) Despite the availability of autologous bone grafts and allografts, which could be transplanted on the side of a bone defect, there are drawbacks related to their limited accessibility, disease transmission, or/and inflammation possibility, which has compelled researchers to seek new alternatives to bone substitutes. (6)
BTE constructs are widely used in literature and focus on different fabrication approaches, material selection, and surface modification to meet bone structure requirements. (7,8) Polyester-based materials are most frequently reported and combined with calcium particles to serve as a platform to induce cell attachment, proliferation, and permit maturation of the cell-laden structure into a healthy bone tissue. (8,9)
Although polyesters such as polycaprolactone and polyglycolide have many outstanding advantages such as low toxicity and processability, they have several limitations, for example, the inability to encapsulate cells, prolonged degradation, and high stiffness that might not fully recapitulate BR conditions. (10)
As previously mentioned, BR is a complex process, and in vitro-induced osteogenesis does not solely pertain to the immediate formation of mineralized tissue. (2) Different types of cells are recruited during BR, where old or damaged bone tissue needs to be resorbed by osteoclasts prior to osteogenesis. As the bone formation process proceeds, it can be divided into two distinct phases: (i) osteoid (preosseous matrix) secretion by osteoblasts; and (ii) its mineralization to obtain calcified bone tissue. (3) Osteoid, a complex interwoven network consisting mainly of collagen type I and bone matrix proteins, is a foundation for bone creation. (11) Thus, its presence should not be neglected in the BTE approach and may be considered essential to answering the question “Is an exceedingly soft starting material required to achieve a calcified bone tissue in vitro?”.
To this aim, hydrogels have been recently used to construct templates guiding bone regeneration by promoting the differentiation of bone cells (12−14) Although their stiffness is insufficient for obtaining mineralized and “ready-to-use” bone tissue, they might provide an ideal, easily tunable platform for osteogenic differentiation and osteoblasts’ preosseus matrix secretion (15,16) Stiffness is a critical parameter in hydrogel-based BTE applications. In fact, it can dramatically influence cell behavior and tissue remodeling. By tailoring the mechanical properties of tissue-engineered constructs, hydrogels can mimic native tissues, parallelly regulating cell adhesion, proliferation, and differentiation. Indeed, the recreation of diverse tissue types can be achieved by regulating the material stiffness and in turn dictating the cell response, thus, making it a pivotal factor for BTE. Besides, hydrogels can also enhance a physiological-like cell response as cells are highly sensitive to their microenvironment. (17)
For this reason, another critical factor for successful BTE is the design and optimization of the hydrogel’s microarchitecture (18,19) which considers the material structure, including pore size, interconnectivity, and pore geometry of the final construct. (20) Among others, microarchitecture plays a pivotal role in determining cell behavior, nutrient diffusion, waste removal, and the formation of functional tissue constructs. (19) Hence, the ability to precisely control and modify the microarchitecture of GelMA hydrogels is of paramount importance. Gelatin methacryloyl (GelMA) is one of the most currently used versatile hydrogels derived from gelatin (21−23) Gelatin is a denatured form of collagen that is a significant component of the ECM in various tissues, including the osteoid matrix. Due to the modification of gelatin with methacryloyl groups, the use of GelMA enables control over the gelation kinetics and mechanical properties. (24) Moreover, GelMA possesses several desirable properties, including biocompatibility, biodegradability, and the ability to be processed into three-dimensional (3D) structures. (25)
Several strategies have been proposed to manipulate the microarchitecture of GelMA hydrogels, including the coordination of gelation and chemical cross-linking. In a study conducted by Young et al., the effect of the dual-cross-linking approach on the mechanical properties of GelMA hydrogels was investigated. (26) These findings revealed a significant increase in the storage modulus (G′), that is 8-fold higher for the hydrogels fabricated using this dual approach than those cross-linked solely through photoinitiated cross-linking. Moreover, similar to the work by Chansoria et al., thermal gelation followed by photo-cross-linking improved cell elongation and proliferation while maintaining the sample shape fidelity after fabrication. (27)
Another versatile approach for fabricating porous scaffolds with easily adjustable pore sizes is the emulsion methodology, which can be described as mixing two immiscible fluids, where one fluid forms droplets within the other. (28) Among others, Pluronic F127, a block copolymer of poly(ethylene oxide) and poly(propylene oxide), remains the most popular option in tissue engineering and in combination with other polymers for the fabrication of sacrificial layers and porous structures (29,30) The polymer solution is a liquid at room temperature (<25 °C), but gels rapidly at body temperature (37 °C). Although the polymer is not degraded by the body, the gels dissolve slowly and the polymer is eventually cleared (31,32) However, due to the limitation of the micelle sizes, this approach has been challenging to fabricate constructs with large pore size. (33) Thus, according to Ying et al. the emulsion of GelMA with poly(ethylene) oxide (PEO) addition might be an alternative for obtaining structures with hierarchical pore structures and controlled pore size (28,33,34)
Here, we aimed to optimize the microarchitecture of GelMA hydrogels to create a platform resembling an osteoid tissue. Two cross-linking methods were proposed: the standard cross-linking involving visible light exposure (VL) and a dual approach (DC) that combined physical gelation and subsequent VL fixation. GelMA concentrations and exposure times were tailored to result in hydrogels with the same stiffness but different microarchitectures.
To our knowledge, this is the first systematic study combining dual-cross-linking and porogen addition to obtain osteoid-like constructs. Furthermore, previous approaches that aimed at targeting the osteoid microarchitectures and mimicking BR-like conditions, such as gradual material degradation, are limited in the literature. In this study, we developed a novel approach for engineering osteoid-like scaffolds by replicating the properties of the osteoid tissue matrix. To this aim, two different cross-linking methods (i.e., SC and DC) were used. It was demonstrated that both achieved a compressive modulus similar to the native osteoid matrix, with G5 DC requiring only half the GelMA concentration, validating the potential of the synergistic effect of the two cross-linking modalities. The G5-DC formulation exhibited the ability to support bone formation during 3 weeks of in vitro incubation. The addition of PEO porogen limited the creation of highly porous hydrogels, thus impairing the osteogenic differentiation due to incomplete PEO extraction.

2. Experimental Section

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2.1. GelMA Synthesis

GelMA was synthesized according to the previously established protocol with minor modifications. (35) In brief, gelatin (porcine skin, type A, 300 g Bloom, Sigma-Aldrich) was reacted with methacrylic anhydride (Sigma-Aldrich) for 1 h at 50 °C. The methacrylic anhydride was added dropwise at 0.6 g of anhydride per gram gelatin, to a 10% (w/v) gelatin in PBS solution, under constant stirring. Prior to the addition of anhydride, the pH of the gelatin solution was adjusted to pH 8, with the addition of a 5 M NaOH solution. Following the reaction, excess anhydride was removed via centrifugation, decanting, and dialysis (cellulose membrane, cutoff 12 kDa, Sigma-Aldrich) against deionized water. The GelMA macromonomer solution was then neutralized, followed by storage at −20 °C for 48 h before freeze-drying and subsequent lyophilization. The as-prepared prepolymer was maintained at −20 °C until further use.

2.2. Quantification of Substitution of GelMA

The degree of functionalization (DoF) of GelMA macromonomers was quantified using proton-nuclear magnetic resonance spectroscopy (1H NMR, Bruker AVIII 300 MHz). Briefly, either unfunctionalized gelatin or the corresponding GelMA macromonomer was dissolved in deuterium oxide (D2O) at 37 °C, and a sample of 0.8 mL of either solution was used for the 1H NMR experiments. The DoF was then calculated from eq 1.
DoF=1−(∫lysinemethyleneprotonofgelMA(2.9ppm)∫lysinemethyleneprotonofgelatin(2.9ppm))×100%
(1)
Prior to interpretation of the NMR spectra, gelatin and GelMA were normalized with respect to the phenylalanine signal at 7 ppm.

2.3. Fabrication of GelMA Hydrogel Samples

2.3.1. Standard Cross-Linking and Dual-Cross-Linking Methods

The hydrogel prepolymer solution was prepared by soaking GelMA in PBS (5 and 10% (w/v)) at 4 °C overnight. Prior to this, in-house synthesized lithium phenyl-2,4,5-trimethylbenzoylphosphinate (LAP) was dissolved in PBS at a concentration of 0.1% (w/v). Subsequently, the GelMA solution was heated up to 40 °C, left stirring for 10 min, transferred to Teflon casting molds, and exposed to visible light (VL) for 10, 13, 30, and 60 s (GelMA-SC). Prior to chemical cross-linking, samples designated as dual-cross-linked (GelMA-DC) were additionally incubated at 5 °C for 1 h.

2.3.2. Microemulsion Approach

To obtain samples with the microemulsion approach, initially, poly(ethylene oxide) (PEO, Mw = 300,000) (Sigma-Aldrich, UK) solution was prepared at the concentration of 1.6% (w/v) in PBS containing 0.1% (w/v) LAP. The solution underwent vigorous stirring at 40 °C for up to 1.5 h. To obtain hydrogel samples containing PEO, GelMA solutions were initially prepared at two different concentrations of 12.5 and 6.25% (w/v). The as-selected concentrations allowed for the incorporation of 20% (v/v) of PEO solution while ensuring that the GelMA remained constant, which equated to 10 and 5% respectively. The same principle was applied when incorporating 10% (v/v) PEO solution, using GelMA concentrations of 11.1% (w/v) for G10 and 5.6% (w/v) for G5, respectively. After the introduction of the PEO solution, the prepolymer solution was stirred for 10 s. Subsequently, the GelMA-PEO blend was then transferred to Teflon casting molds and cross-linked for 13 s (DC) and 60s (SC). Prior to this, dually cross-linked hydrogel samples were incubated at 5 °C for 1 h.
To ensure the clarity and transparency of the presented results, GelMA conditions tested in the present study are listed in Table 1, together with their simplified naming.
Table 1. Composition of Materials Employed and Their Crosslinking Method

2.4. Mechanical Properties of GelMA

2.4.1. Gelation Kinetics Assessment

Rheological measurements of G10 subjected to VL cross-linking and dual cross-linking were performed using a rheometer with a Peltier plate temperature system and a 20 mm serrated parallel plate accessory. The storage modulus and loss modulus of the samples were registered during the constant frequency of 1.6 Hz and sweeping temperature from 25 to 5 °C at a cooling rate of 3 °C/min. The respective hydrogel working solutions were incubated then up to 39 h. Young’s modulus was calculated based on the storage modulus of the sample, assuming a Poisson ratio of 0.5.

2.4.2. Compressive Modulus Determination of GelMA Samples

The compressive modulus of GelMA-based samples was assessed using a dynamic mechanical analyzer (DMA) (Q800, TA Instruments, USA) at 37 °C with a 0.001 N preload force. Prior to analysis, cylindrical samples (n = 5) with a diameter of 6 mm and 1.6 mm in height were incubated in PBS overnight at 37 °C. Subsequently, specimens were subjected to a static compression test at a strain rate of 30%/min. The compressive modulus was calculated based on the slope of the linear region of the stress–strain curve in the range of 2–4% strain of the sample.

2.5. Swelling Behavior Determination

Hydrogel samples were dehydrated in increasing ethanol concentrations (Sigma-Aldrich, USA)─50, 70, 80, 90, and 2 × 100%, and left for overnight drying. To assess the stability of GelMA specimens, cylindrical samples (n = 5) were immersed in PBS solution and incubated for up to 72 h at 37 °C. At specified time points (every 10 min for the first hour, every 30 min for the second and third hours, every 60 min for the fifth hour, and then after 24, 48, and 72 h), the samples were collected, the excess water was gently wiped out, and the specimens were weighed again. The swelling degree (H) of each GelMA condition was evaluated using the following eq 2:
H(%)=((mwet−m0/m0)
(2)
where m0 is the initial weight of the dehydrated sample before immersion, and mwet is the weight of the swollen sample measured at a fixed time point.

2.6. Porosity Calculations Using Microcomputed Tomography

Microcomputed tomography (micro-CT) analysis using the SkyScan 1172 system (Bruker, USA) was conducted to evaluate the porosity of GelMA-based samples. The GelMA samples were prepared following the procedure mentioned in Section 2.3. After fabrication, the samples at day 0 (D0) were stored at −80 °C and subsequently freeze-dried for 24 h. Samples designated as D1 underwent the same procedure after being immersed in DMEM-LG supplemented with 10% FBS and 1% PS for 24 h. The GelMA-based substrates were then subjected to micro-CT scanning with a source voltage of 40 kV and a source current of 250 μA. The resulting pixel size was 4 μm. During the scanning procedure, each sample was rotated by 180° with a step size of 0.15° and an exposure time of 80 ms.

2.7. Metabolic Activity of Cells during Cold Treatment

To evaluate the metabolic activity, human bone marrow-derived mesenchymal stem cells (hBMSC) were cultivated in low glucose DMEM supplemented with 10% fetal bovine serum (FBS) (EuroClone, Italy) and 1% penicillin-streptomycin (PS) (Gibco, USA). The cells from passage 8 were embedded (106 cells/mL) in G10-SC and G5-DC and chemically cross-linked for 60 and 13 s, respectively. Cell-laden G5-DC specimens were physically cross-linked prior to visible light exposure, as previously optimized. Subsequently, the alamarBlue assay (Invitrogen, USA) was used to compare cell metabolic activity in G10-SC and G5-DC microarchitectures. In brief, cell-laden samples were introduced into 24-well plates filled with 900 μL of cell culture medium and incubated at 37 °C under 5% CO2. After 30 min of incubation, 100 μL of alamarBlue solution was added to the corresponding wells and incubated for 1h. The percentage of reduction of alamarBlue was then measured spectrometrically (FLUOstar Omega, BMG LABTECH, Germany) at 570 and 600 nm, according to the manufacturer’s specification. Subsequently, cell culture medium was removed, replaced with a fresh one and the samples were again incubated for up to 4 and 24 h. Results are presented as % of control; the 2D control involved seeding cells into a multiwell plate, followed by incubation under the same conditions as cells introduced to hydrogel substrates.

2.8. In Vitro Evaluation of Cell-GelMA Interactions

2.8.1. Cell Culture

hBMSCs were expanded in a growth medium consisting of low glucose DMEM (ThermoFisher, USA), 10% FBS, and 1% PS, supplemented with 1 ng mL–1 human basic fibroblast growth factor 2 (hFGF) (Sigma-Aldrich, USA) until sufficient confluence was obtained. Cells from passage 5 were detached using trypsin–EDTA 1× (Gibco, USA) and embedded in GelMA-based constructs. Briefly, 4 × 103 cells/mL were suspended in GelMA solutions (G5 and G10) and cross-linked as previously optimized. For PEO-containing specimens (G5-ME and G10-ME), cells were loaded in PEO solution and then transferred into GelMA. The growth medium was used up to day 4 of culturing, after which differentiation medium based on α-MEM-GlutaMAX TM (ThermoFisher, USA), 10% FBS, 1% PS, supplemented with 100 nM dexamethasone (Sigma-Aldrich, USA), 10 nM 1α, 25-dihydroxyvitamin D3 (Sigma-Aldrich, USA), 2 mM ß-glycerophosphate disodium salt hydrate (Sigma-Aldrich, USA), and 50 mM l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate (Sigma-Aldrich, USA) was used to induce osteogenesis. The differentiation medium was changed every two to 3 days up to day 21. The cell-laden constructs (n = 3 for each condition) were incubated at 37 °C under 5% CO2. The specimens cultivated up to day 21 in a growth medium [named nondifferentiated (ND)] served as a control.

2.8.2. Cell Viability Evaluation

Cell viability was determined using a LIVE/DEAD Cell Viability Kit (Invitrogen, USA, R37601) to investigate the response of cells encapsulated within different GelMA microarchitectures. At fixed time points of culture, that is, days 7, 14, and 21, samples were washed twice with PBS and immersed in 0.5 μL mL–1 calcein and 2 μL mL–1 ethidium homodimer. Calcein was used for staining live cells in green, while the ethidium homodimer was added for staining dead cells in red. Samples were incubated for 20 min at 37 °C and 5% CO2. Subsequently, samples were washed with PBS and imaged with a fluorescence microscope (Leica TCS SP8, Leica Microsystems, Germany) at wavelengths corresponding to fluorophores of interest. The number of alive (green, G) and dead cells (red, R) was quantified from fluorescence images using the counting algorithm of ImageJ (National Institute of Health, USA) on separate red and green channels of three different areas of independent samples (n = 3). The viability (%) was estimated using the equation G/(G + R) × 100.

2.8.3. Characterization of Cell Morphology

Cell morphology was investigated by staining the cell actin filaments and nuclei. In brief, at days 7, 14, and 21 of incubation, GelMA constructs were washed with HEPES, and 4% paraformaldehyde was used to fix the specimens at 4 °C overnight. Subsequently, the specimens were washed with HEPES three times for 5 min each. Afterward, 0.3% (v/v) Triton X-100 in HEPES was added for 15 min, and samples were washed thrice. Hydrogel samples were then incubated in 1% (w/v) BSA in HEPES for 30 min and a 1:40 dilution of Alexa Fluor 488 Phalloidin (ThermoFisher, USA) in HEPES was added for 40 min at room temperature (RT). Afterward, specimens were washed and incubated in 1:1000 DRAQ5 (ThermoFisher, USA) solution diluted in HEPES for 10 min to visualize cells’ nuclei. Upon washing, samples were imaged under a confocal microscope (Leica TCS SP8).

2.8.4. Alkaline Phosphatase Activity and DNA Quantification

Samples were removed from the medium and washed twice with PBS on days 7, 14, and 21, followed by freezing at −80 °C. To allow for GelMA disintegration and cell lysis, each sample was thawed and immersed in collagenase type II solution (Sigma-Aldrich, USA) (50 CDU in 200 μL of PBS) at 37 °C for 2 h, followed by its refreezing at −80 °C. To detect ALP activity in different microarchitectures of GelMA over the incubation period, the para-nitrophenylphosphate (p-NPP) method was used (Sigma-Aldrich, USA). A 50 μL portion of cell lysate was transferred into a 96-well plate, and an equal volume of diluted p-NPP was added to each well. The working solution was then incubated at room temperature for 45 min, and the absorbance was measured at 405 nm. The ALP activity was normalized by the DNA content. The DNA content was measured by a CyQUANT assay (Thermofisher, USA) using a DNA-based standard curve.

2.9. Statistical Analysis

Data are expressed as a mean ± standard deviation (SD). Two-way ANOVA followed by Tukey multiple comparisons and one-way ANOVA were performed using GraphPad Prism version 9.0 for Mac OS X, GraphPad Software, La Jolla California USA. Statistically significant values are displayed as *p value 0.0332 (*), 0.0021 (**), 0.0002 (***), and <0.0001 (****).

3. Results and Discussion

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Herein, the physical properties of GelMA were optimized to obtain four different osteoid-resembling hydrogel microarchitectures. We have decided to use GelMA hydrogel, which can be precisely and quickly tuned to promote bone formation in the long run. (36) Additionally, for our bone tissue engineering application, we required hydrogels with a greater stiffness and increased resistance to degradation through hydrolysis. To meet these criteria, GelMA with a high degree of functionalization (DoF) following the established protocol (35) was synthesized and subsequently quantified using 1H NMR spectroscopy (Figure 1A). The conversion of amine groups to methacrylamide was indicated with a peak around 2.9 ppm, corresponding to the lysine methylene proton on the gelatin backbone, having diminished. The ratio of integrals of this peak at 2.9 ppm between the gelatin and GelMA spectra, after normalizing to the phenylalanine peak at 7 ppm, was used to quantify the DoF for the GelMA macromonomers at 79 ± 4%. Additional peaks were observed around 5.5 ppm, corresponding to the acrylic protons on the methacrylamide and methacrylate groups, while residual signals on the GelMA spectrum showed similar chemical shifts and intensities to those of the gelatin, thus indicating that the primary structure of the gelatin molecule had been maintained during the reaction. While following a frequently employed protocol for assessing the DoF in GelMA, (33,37,38) future considerations for unbiased quantification could involve the utilization of a reference molecule such as 3-(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt (TMSP), (39) potentially offering more accurate results. Two different strategies of GelMA cross-linking (Figure 2B) were proposed to obtain a stiffness like collagen-rich osteoid, which is estimated to be 27 ± 10 kPa. (40) The first cross-linking strategy involved immobilizing the polymer chains of GelMA through exposure to visible light. As this method is widely used in tissue engineering, we have decided to classify it as a standard cross-linking (SC) and treat it as a reference for further material optimization. Granting that light-induced cross-linking is a rapid process to obtain defined properties of hydrogels, the challenge lies in creating robust structures that simultaneously enhance cell viability and degrade at a predetermined rate. Moreover, the biodegradation rate of such hydrogels is reduced, making them less attractive for tissue engineering applications. However, the compromise between what is required and what is possible must always be considered. Indeed, studies have reported that GelMA hydrogels with low monomer concentrations (approximately 5%) and lower degrees of substitution (DS) are more favorable for supporting embedded cell proliferation, sprouting, and network formation, especially for vascular cells (41,42) However, the problem arises when stiff constructs are needed to be obtained. One of the methods of creating stiff GelMA constructs is locking in the complex structures and hydrogel bonds permanently by combining thermal gelation and chemical cross-linking. Thus, we have decided to implement a two-stage cross-linking, that is, physical gelation followed by visible light exposure (Figure 1B) to easily tune the microarchitecture of GelMA without hampering their initial stiffness, simultaneously creating a more appropriate environment for bone cells’ survival and maturation. The method of reversible physical cross-linking was previously explained as the formation of helical chains in the structure of GelMA (26,43) Weak hydrogen bonds are formed between gelatin and water, creating a disorganized net of partial helices and trapped water. To effectively lock in the structure of the hydrogel, photoinitiated cross-linking was eventually applied. Having this in mind, it was believed that with the use of a low concentration of GelMA and reduced chemical cross-linking time, the stiff constructs might be obtained when neither the prolonged exposure to light (≥60 s) nor the high (≥10%) concentrations of GelMA are used.

Figure 1

Figure 1. GelMA synthesis and cross-linking strategies: (A) 1H NMR spectra of unfunctionalized gelatin and GelMA in D2O. The peak around 2.9 ppm is associated with the lysine methylene proton on the gelatin backbone and was used to monitor the methacrylation reaction and determine the degree of functionalization; (B) schematic illustration of two strategies of GelMA cross-linking presented in the current work: (I) dual cross-linking based on physical gelation at 5 °C, followed by photoinduced cross-linking and (II) standard cross-linking based on the visible light exposure.

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Figure 2

Figure 2. Optimization of GelMA cross-linking parameters to match the stiffness of osteoid tissue: (A) rheological and mechanical characterization of G10 exposed to physical cross-linking only (PC) and DC incubated up to 39 h at 5 °C, PC + SC─hypothetical value of dual-cross-linking plotted as physical gelation + offset value for chemically cross-linked G10; Poisson ratio of 0.5 assumed to convert moduli through E = 3·G; (B) compressive modulus of G5-SC and G5-DC samples incubated at 5 °C for 1 h followed by chemical cross-linking up to 180 s; significant difference was observed within various cross-linking times of G5-DC with the p < 0.0001 (****) apart from 10 vs 13 s (ns) and 30 vs 60 s (ns); the p < 0.0001 (****) was also noted between G5-SC and G5-DC (each cross-linking time).

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3.1. Effects of Cold Incubation Prior to VL Cross-Linking on the Mechanical Properties of GelMA

The stiffness of 10% (w/v) GelMA gels increased by a factor of 7 when the precursor solution was incubated for 1 h or more (up to 39 h) before VL cross-linking (i.e., dual cross-linking) compared to direct VL cross-linking of the precursor solution without cold incubation: 164 ± 9 vs 23 ± 1.4 kPa. The kinetics of physical cross-linking were assessed by conducting rheological characterization of a 10% GelMA solution incubated at 5 °C for almost 50 h and following the increase in shear modulus over time (Figure 2B, curve labeled PC for physical cross-linking). To understand if the effect of physical gelation is additive or synergistic to chemical cross-linking through VL exposure, we plotted the time-dependent increase of shear modulus that resulted from physical cross-linking at an offset of the modulus obtained by chemical cross-linking for G10 (Figure 2A, curve PC + SC). To enable this comparison between shear and compressive moduli, a Poisson ratio of 0.5 was assumed. It is evident that the compressive modulus of DC gels (Figure 2B scatter plot DC) is much higher than the combined effect of SC and physical cross-linking, demonstrating the synergistic effect of the two types of cross-links being in agreement with the literature. (26) Despite physical cross-linking still increasing up to 49 h incubation as evidenced, Young’s modulus of G10-DC gels increased with time only over the first hour, after which it reached its plateau value. In light of this, the choice of GelMA incubation conditions proved to be relatively uncomplicated. Our findings indicate that a 1 h incubation at 5 °C is sufficient to reach the desired stiffness. (44,45)
Following optimization of the incubation time, the photo cross-linking time for G5-DC was studied and compared to light-exposed G5-SC (Figure 2B). As for the 10 wt % gels, the 1 h of cold incubation prior to VL cross-linking caused an 8x increase in stiffness. Furthermore, the stiffness of the G5-DC hydrogels demonstrated a notable increase in response to VL exposure. Specifically, the compressive modulus elevated from 11.91 ± 1.2 to 24.39 ± 4.12 kPa when exposed for 10 and 60 s, respectively. Conversely, the stiffness of the G5-SC constructs exhibited minimal fluctuations consistently measuring around ∼3.12 kPa across all tested conditions. Moreover, it was found that exposing G5-DC samples to 180 s of VL-cross-linking resulted in the formation of very brittle hydrogel structures which disintegrated upon manipulation. This finding was believed to be the result of the formation of an exceedingly high number of chemical cross-links, which prevents the extension of polymer chains in response to an applied load. (46) To achieve comparable stiffnesses to G10-SC, G5-DC samples were cross-linked with VL for 13 s to give a compressive modulus of 18.12 ± 1.66 kPa (Figure 3A).

Figure 3

Figure 3. Characterization approaches of G10-SC and G5-DC: (A) influence of the time of chemical cross-linking on the compressive modulus of G10-SC and G5-DC detected using DMA; #─literature-based compressive modulus of osteoid tissue; (B) swelling degree of the samples fabricated using different strategies of cross-linking and incubated in PBS up to 72 h at 37 °C; (C) metabolic activity of hBMSCs embedded into G10-SC and G5-DC determined by an Alamar Blue assay; metabolic activity is presented as a % of reduced resazurin by hBMSCs cells vs 2D control.

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3.2. Advancing GelMA Cross-Linking Strategies for the Generation of Osteoid-like Stiffness

To obtain hydrogels of different microarchitectures but matched stiffness in the range of osteoid tissue, the cross-linking time was adjusted for both G10-SC (60 s) and G5-DC (13 s) gels (Figure 3A). To validate the effect of dual cross-linking on the physical properties of GelMA, the swelling degree of G5-DC was compared to the G10-SC. It was assumed that the use of a lower concentration of GelMA macromonomer would result in accelerated degradation, thereby closely resembling the natural remodeling conditions of bone tissue. In this study, it was found that G5-DC compared to G10-SC showed a higher initial water uptake over 180 min (Figure 3B), when constructs were incubated at 37 °C (784.7 ± 68.5% vs 652.03 ± 15.9% for G5-DC vs G10-SC), which is in agreement with the literature. (47) Surprisingly, this trend was not observed across the whole incubation period, where after 7 h of the samples being immersed in PBS, specimens of G5-DC and G10-SC showed similar swelling behavior, that is, 655.68 ± 51.90 and 640.92 ± 14.59%, respectively. This swelling behavior was found to be affected considerably by shrinkage of G5-DC samples (∼26% compared to G10-SC) after immersion in PBS at 37 °C.
We compared the metabolic activity of the relevant cell type human bone marrow-derived mesenchymal stem cells hBMSCs encapsulated in GelMA platforms with different concentrations and cross-linking strategies (Figure 3C). hBMSCs were chosen as they have the ability to differentiate into osteoblasts and hence contribute to the process of bone tissue reproduction and growth. (48) Therefore, it was essential to prove that hBMSCs will remain alive once in contact with the material during two-stage cross-linking. The metabolic activity of cells was assessed by measuring the percentage of resazurin reduced at 1, 3, and 24 h after encapsulation in G5-DC and G10-SC samples. During the first hour of incubation, the percentage of reduced resazurin was ∼81 and ∼86% for G5-DC and G10-SC, after which the metabolic activity of cells stabilizes over the incubation period reaching a final value of 83.2 ± 1.2 and 83.5 ± 1.1% for G5-DC and G10-SC, respectively, at day 1 of incubation. This corresponds to the results obtained during water absorption measurements, where the tendency of water uptake of G5-DC and G10-SC samples also stabilizes after 24 h of incubation. The evaluation of metabolic activity of cells encapsulated within G5-DC and G10-SC demonstrated that the fabrication and cross-linking strategies did not exert any toxicity on hBMSCs. The slightly reduced values observed in the hydrogel samples, in contrast to those in 2D, may be attributed to the differences between 2D and 3D environments. In the 2D cell configuration, more rapid proliferation could be observed, resulting in higher value intensities. Furthermore, the 2D systems exhibit a faster exchange of resazurin/resorufin when compared to the 3D gel structures. Additionally, it is possible that the hydrogels retained some of the resorufin, which could account for the lower readings of the metabolic activity.
Once cross-linking strategies were optimized, a microemulsion approach to obtain structures of G5-DC and G10-SC which contain PEO as a porogen was introduced. As was previously discussed, PEO enables adjustable micropore formation in the structure of GelMA and, thus, could provide the opportunity to enhance cell spreading and tissue formation. (34) To achieve a hydrogel structure with a greater hierarchical pore arrangement, the concentration of GelMA prepolymer solutions was adjusted accordingly to maintain the desired concentrations of G5 and G10 following the addition of 10 and 20% (v/v) PEO solution. Consequently, specimens were cross-linked forming constructs, which we will designate in this paper as G5-ME (two-stage cross-linking) and G10-ME (exposed to VL). The incubation of specimens in PBS for 24 h at 37 °C was assumed to enable PEO removal from the structure of the hydrogels. Prior to the detection of morphological changes in the structure of hydrogels upon PEO removal, we evaluated G10-ME and G5-ME in terms of their stiffness. It was believed that the removal of PEO would cause a decrease in the compressive modulus of specimens due to an increase in porosity as was presented in the work of Ying et al. (33) Thus, we have decided to focus on PEO addition up to 20 vol % into the prepolymer solution not to observe a severe drop in their initial stiffness after cross-linking. Surprisingly, the results were in contrast to those shown in the above-mentioned publication, where we observed that with an increased concentration of PEO, the compressive modulus did not change significantly for G5-ME and G10-ME─remaining at ∼18 kPa regardless of the percentage of PEO (Figure 4A). The differences between our results and those presented in the literature may be due to different GelMA concentrations. In our experiments, the GelMA prepolymer solution was concentrated before adding PEO solution, whereas the approach presented by Ying et al. focused on GelMA solution dilution. (28) Even though noticeable changes in material stiffness were not observed, the ratio of weight percentage of PEO to GelMA was relatively small, that is, ∼6 and 3 wt % for G5 and G10, respectively, so it should not be surprising that the differences may not have been visible at first glance.

Figure 4

Figure 4. Characterization of GelMA constructs with PEO addition/removal: (A) compressive modulus of G5- and G10-based specimens; samples without PEO addition served as a control─G5-DC and G10-SC; (B) water absorption determination of G5- and G10 samples with 20 vol % addition after 24 h of incubation in PBS at 37 °C compared to pristine G5-DC and G10-SC.

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To investigate the microarchitecture of the GelMA hydrogels developed in this work, water absorption up to 72 h was studied on samples incubated at 37 °C (Figure 4B). This experiment was used to make predictions on the porosity of the hydrogel constructs, where it was assumed that a greater water uptake correlated with an increased PEO removal from the hydrogel, could result in a high porosity. The results show a lower degree of water uptake for G5-ME and G10-ME compared to G5-DC and G10-SC, suggesting that there could be insufficient removal of PEO from the structure of the hydrogels. It was also observed that the swelling degree after 24 h of incubation stabilizes, reaching ∼625%.
To further investigate whether PEO remains in the structure of the hydrogels after 24 h of incubation in PBS or cell culture medium, optical images of GelMA-based samples were taken (Figure S1). Samples containing 20 vol % PEO globules were opaque compared to transparent specimens of G5-DC and G10-SC just after its fabrication (D0). Significant removal of PEO from the GelMA structure after 24 h of incubation was not observed, as initially intended (Figure 5A) Micro-CT analysis was performed to evaluate the porosity of the samples. The results presented in Figure 5B indicated a decrease in porosity with increasing GelMA concentration. Specifically, the porosity was 87% for G5-DC and 21% for G10-SC at D0. The addition of PEO to G5-DC and G10-SC, resulting in G5-ME and G10-ME, further reduced the porosity by approximately 38 and 86%, respectively, compared with the pristine samples at D0. However, it should be noted that the incomplete removal of PEO was evident as the porosity for G5-ME reached only 3%. The porosity for G10-ME samples was slightly higher but not significantly different from D1. Overall, the optical and micro-CT analysis confirmed together with FTiR and TGA spectra (Figures S4 and S5, respectively) the presence of PEO in GelMA-based hydrogels even after 24 h of incubation, indicating the challenges associated with complete PEO removal from the microarchitecture.

Figure 5

Figure 5. Quantification of porosity changes in freeze-dried G5- and G10-based samples: (A) schematic workflow of intended PEO removal from GelMA structure during 24 h incubation; (B) micro-CT scan reconstructions at day 0 (D0, samples were fabricated according to the cross-linking approach and then freeze-dried) and day 1 (D1) of incubation in DMEM-LG medium supplemented with 10% FBS and 1% PS. The images are shown as a region of interest (ROI) of the sample with x and y equal to 2.5 mm.

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3.3. Evaluation of Biological Properties of GelMA-Based Constructs

hBMSC was selected to cellularize the microarchitectured GelMA due to its in vitro osteogenic differentiation potential. Cell-laden constructs were tested for up to 21 days (Figures 6 and S2). Cell viability was evaluated by live/dead assay and all tested conditions exhibited high cell viability (>90%) at day 7 (Figure 6A). Cells encapsulated in G5-based samples did not show any significant difference between the two investigated groups (i.e., G5-DC and G5-ME) up to 2 weeks of culture (day 14). Cell adaptation over the culture time (i.e., up to day 21) was detected in G5-DC structures, with no significant changes in the viability, thus speculating the positive influence of the dual cross-linking approach on the proposed hydrogel. Additionally, the structural integrity of G5-based samples was well-preserved throughout the cultivation period, as shown in Figure S3. However, a gradual degradation of G5-DC was evident, with a transition toward a more transparent-like structure at day 21 compared to day 7, highlighting the ongoing remodeling process of the hydrogel construct. Unfortunately, increased proliferation of hBMSCs embedded in G5-ME was not observed as it was anticipated by Ying et al., where the viability of HepG2 loaded into PEO-containing GelMA increased by 7% compared to the pristine samples at day 7. (33) In our case, the viability of porous G5-ME samples significantly decreased compared to that of the G5-DC counterpart at day 21 (76.52 vs 95.07%. respectively), likely due to the low adaptability of cells to the nonremoved PEO phase. On day 21, G5-ME showed a 21.73% lower cell survival than that on day 7. A similar trend was observed in the case of G10-ME, where cell survival displayed a 15.35% drop in the same time range (from day 7 to day 21). G10-SC did not show any change in cell viability over the culture time, although a significant difference in cell viability was observed when comparing G10-SC to G10-ME at day 7 and day 21 (98.28 vs 93.74% and 90.52 vs 78.39%, respectively). These results do not provide support for the hypothesis that the PEO phase promoted cell growth and enhanced the biocompatibility of the GelMA hydrogel after a 3-week culture. Such observations contradict previous studies that showcased the viability of the porous GelMA-PEO hydrogels. As previously mentioned, the incomplete removal of PEO globules in our case can be attributed to the dense network structure of GelMA, resulting in globules entrapment within the shrunk G5-based substrates. (28)

Figure 6

Figure 6. Biological evaluation of GelMA hydrogel constructs. (A) hBMSC cell viability over 3 weeks of incubation in osteogenic medium, (B) cell morphology visualization with actin (green) and cell nuclei (blue) staining, (C) bright-field images of G5- and G10-based samples at day 21 (D21) of incubation in osteogenic medium. Scale bar 300 μm; p = 0.0021 (**), < 0.0001 (***).

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Furthermore, cell spreading and morphology were also evaluated over 3 weeks of culture time by actin staining to understand the influence of the different fabrication and gelation methods on the cytoskeleton structure (Figure 6B). In G5-DC, cells freely spread in all directions within the hydrogel constructs up to day 21, as confirmed from the elongated and nonoriented actin filaments. At day 21, cells formed a more interconnected intercellular network of fused cytoskeletons, showing that hBMSC morphology is positively affected by the dual-cross-linking method. Culture of hBMSCs in G5-ME, G10-ME, and G10-SC (which had a comparable stiffness to G5-DC) hydrogels resulted in limited cell proliferation and elongation without notable spreading over time. This supports the hypothesis that tuning stiffness alone is not sufficient for designing hydrogels that facilitate neotissue maturation; microarchitecture is just as an essential factor if not more important. Furthermore, it is possible to speculate that PEO removal in porous structures (i.e., G5-ME and G10-ME) did not fully occur (Figure 6C), thus hampering the creation of void-forming hydrogels and, in turn, osteoid tissue formation. Similar results were obtained for G10-SC, where the high GelMA macromonomer concentration in the hydrogel resulted in a gel with low permeability, limiting both PEO removal and cell maturation.
Comparison of the normalized alkaline phosphatase (ALP) activity to the DNA content was conducted to provide valuable insights into the osteogenic potential and cellular behavior within different hydrogel materials (Figure 7). In our study, four GelMA-based hydrogels were cultivated in osteogenic medium for up to 3 weeks, while the samples incubated in nonosteogenic medium served as a negative control (Figure S6). Throughout the cultivation period, all hydrogels exhibited an increase in ALP activity, indicating successful osteogenic differentiation of the cells within the hydrogel materials (Figure 7A). Moreover, nondifferentiated hydrogel samples showed 2-fold reduction in ALP activity compared to those undergoing osteogenic differentiation (Figure S6). Notably, the hydrogel without PEO addition, G5-DC, demonstrated the highest ALP/DNA content up to day 21. The ALP production was particularly prominent at day 14 (0.46 ± 0.06) for G5-DC, followed by a slight decrease to approximately 0.3 at day 21, which is consistent with previous findings. (36) In comparison, the ALP/DNA content for G10-SC was 0.26 ± 0.3 on day 14 and 0.31 ± 0.07 on day 21. Interestingly, the DNA content (Figure 7B) at the same time points was significantly lower for G5-DC, approximately 45 and 39% at day 14 and day 21, respectively, compared to G10-SC. This discrepancy suggests the possibility of cells escaping from the shrunk architecture of the G5-DC samples (Figure 7C). Notably, the DNA content increased for the dually cross-linked samples (G5-DC and G5-ME), indicating ongoing cell proliferation within the microarchitecture. As anticipated, the addition of PEO to the hydrogel substrates did not significantly enhance osteogenic differentiation.

Figure 7

Figure 7. ALP expression and DNA content during the in vitro culture of G5- and G10-based samples: (A) normalized alkaline phosphatase (ALP) activity to DNA content over 3 weeks of incubation in osteogenic medium, (B) single data set representing DNA levels used for ALP normalization, (C) image of shrunk G5-DC sample after immersion in cell culture medium for 24 h, which revealed the presence of escaping cells from the structure of the hydrogel; #─significant difference compared to D7-G5DC, D7-G5ME and D14-G5DC (p 0.0021); $─compared to D14-G5ME (p 0.0332); *─D7-G5DC, D7-G5ME, D14-G5DC; (p 0.0332); @─D21-G10SC, D21-G10ME (p 0.0332); &─D21-G10SC, D21-G10ME (p 0.0332); **─D21-G10SC, D21-G10ME (p 0.0332).

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4. Conclusions

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This study aimed to optimize the physical properties of GelMA hydrogels to create osteoid-like microarchitectures for bone tissue engineering applications. GelMA was chosen due to its tunability and ability to promote bone formation. Two cross-linking strategies were proposed: standard cross-linking (SC) using visible light and a two-stage cross-linking approach combining physical gelation and visible light (VL) exposure.
By reducing the GelMA concentration from 10 to 5% and implementing physical gelation prior to VL, we have achieved a stiffness comparable to an osteoid matrix (27 ± 10 kPa). (40) We demonstrated that physical gelation did not compromise cell viability during 1 h of incubation at 5 °C, and the DC strategy promoted bone tissue formation as evidenced by alkaline phosphatase (ALP) measurements. Furthermore, to establish hierarchically porous GelMA constructs for enhanced bone formation, we proposed the addition of 20 vol % PEO into the hydrogel structure. However, the PEO was confirmed to be locked in the dense structure of the polymer network and insufficiently removed due to both significant shrinkage of DC-based samples and porosity reduction from 87 to 29% for G5-DC just 1 day postfabrication. Similar trends were observed in GelMA 10% constructs exposed to VL.
The viability of human bone marrow-derived mesenchymal stem cells (hBMSCs) encapsulated in GelMA platforms was not inhibited by physical gelation, and cells remained viable throughout the incubation period. Moreover, hBMSCs in dual-cross-linked gels showed an increased ability to spread, formed intercelluluar connections, and remodeled the matrix, alongside increased expression of the early osteogenic marker alkaline phosphatase compared to those in standard-cross-linked GelMA of the same stiffness. This underlines the importance of the microarchitecture in hydrogel-based tissue engineered scaffolds.
Micro-CT analysis confirmed that the porosity of the constructs can be reduced by increasing GelMA concentration and in turn adding poly(ethylene oxide) (PEO). Surprisingly, the addition of PEO as a porogen did not allow for the formation of hydrogel structures with hierarchical pore arrangements. During the incubation period, it was observed that PEO globules remained trapped within the structure of the 5% GelMA hydrogels. This was due to the physical cross-linking, which effectively locked in the PEO globules within the hydrogel matrix. As a result, the hydrogel porosity was hindered on the first day of incubation. Furthermore, when GelMA was used with a higher concentration (10%), the dense polymer network prevented the complete removal of the porogen material. Only the untrapped globules on the surface of the hydrogel were removed, while those embedded within the structure remained enmeshed.
These observations shed light on the challenges associated with influencing the porosity of GelMA hydrogels, specifically when using PEO as a porogen. The physical cross-linking and the dense polymer network of GelMA at higher concentrations can impede the complete removal of porogens, leading to reduced porosity within the hydrogel structure.
Overall, this study highlights the potential of coordinated physical gelation and chemical cross-linking to produce hydrogels with substantially enhanced mechanical properties and high cell viability─conditions that favor bone tissue formation. These findings contribute to the development of biomimetic hydrogel scaffolds for bone tissue engineering applications.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.biomac.3c00909.

  • Additional experimental details of qualitative observations of structural stability of GelMA-based samples, infrared spectra and thermogravimetric analysis of freeze-dried constructs, and APL/DNA content of GelMA hydrogel samples (PDF)

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Author Information

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  • Corresponding Authors
  • Authors
    • Ferry P. W. Melchels - Future Industries Institute, University of South Australia, Adelaide, South Australia 5095, Australia;  Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, Scotland;  Orcidhttps://orcid.org/0000-0002-5881-837X
    • Alessia Paradiso - Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
    • Andrew McCormack - Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh EH14 4AS, Scotland
    • Karol Szlazak - Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
    • Alicja Olszewska - Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, Warsaw 02-507, Poland
    • Michal Srebrzynski - Department of Transplantology and Central Tissue Bank, Medical University of Warsaw, Chalubinskiego 5, Warsaw 02-004, Poland;  National Centre for Tissue and Cell Banking, Chalubinskiego 5, Warsaw 02-004, Poland
  • Author Contributions

    The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This research was supported by grant no. UMO-2021/41/N/ST5/04220 from the Polish National Science Centre and by the “Excellence Initiative─Research University” at the Warsaw University of Technology (04/IDUB/2019/94) within the Mobility PW program. This work was also partially supported by the National Centre for Research and Development under grant no. POLTUR4/BIOCANCER/3/2021. Figure 5A was partially created with BioRender.com. We would like to thank Maciej Łojkowski and Dr Emilia Choińska for their support with FTiR and TGA measurements.

References

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This article references 48 other publications.

  1. 1
    Salhotra, A.; Shah, H. N.; Levi, B.; Longaker, M. T. Mechanisms of Bone Development and Repair. Nat. Rev. Mol. Cell Biol. 2020, 21 (11), 696– 711,  DOI: 10.1038/s41580-020-00279-w
    Google Scholar
    1
    Mechanisms of bone development and repair
    Salhotra, Ankit; Shah, Harsh N.; Levi, Benjamin; Longaker, Michael T.
    Nature Reviews Molecular Cell Biology (2020), 21 (11), 696-711CODEN: NRMCBP; ISSN:1471-0072. (Nature Research)
    Abstr.: Bone development occurs through a series of synchronous events that result in the formation of the body scaffold. The repair potential of bone and its surrounding microenvironment - including inflammatory, endothelial and Schwann cells - persists throughout adulthood, enabling restoration of tissue to its homeostatic functional state. The isolation of a single skeletal stem cell population through cell surface markers and the development of single-cell technologies are enabling precise elucidation of cellular activity and fate during bone repair by providing key insights into the mechanisms that maintain and regenerate bone during homeostasis and repair. Increased understanding of bone development, as well as normal and aberrant bone repair, has important therapeutic implications for the treatment of bone disease and ageing-related degeneration.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhslOnsrrO&md5=07ce32de7369b65e140e0a5e8eecea0b
  2. 2
    Bolamperti, S.; Villa, I.; Rubinacci, A. Bone Remodeling: An Operational Process Ensuring Survival and Bone Mechanical Competence. Bone Res. 2022, 10 (1), 48,  DOI: 10.1038/s41413-022-00219-8
    Google Scholar
    2
    Bone remodeling: an operational process ensuring survival and bone mechanical competence
    Bolamperti, Simona; Villa, Isabella; Rubinacci, Alessandro
    Bone Research (2022), 10 (1), 48CODEN: BROEBB; ISSN:2095-6231. (Nature Portfolio)
    Abstr.: Bone remodeling replaces old and damaged bone with new bone through a sequence of cellular events occurring on the same surface without any change in bone shape. It was initially thought that the basic multicellular unit (BMU) responsible for bone remodeling consists of osteoclasts and osteoblasts functioning through a hierarchical sequence of events organized into distinct stages. However, recent discoveries have indicated that all bone cells participate in BMU formation by interacting both simultaneously and at different differentiation stages with their progenitors, other cells, and bone matrix constituents. Therefore, bone remodeling is currently considered a physiol. outcome of continuous cellular operational processes optimized to confer a survival advantage. Bone remodeling defines the primary activities that BMUs need to perform to renew successfully bone structural units. Hence, this review summarizes the current understanding of bone remodeling and future research directions with the aim of providing a clin. relevant biol. background with which to identify targets for therapeutic strategies in osteoporosis.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVGlsr%252FM&md5=23f3dd378dc01345736e4bbf5b59d164
  3. 3
    Marotti, G. Morphological and Quantitative Aspects of Bone Formation and Mineralization. In Bone Regulatory Factors; NATO ASI Series; Pecile, A.; de Bernard, B., Eds.; Springer US: Boston, MA, 1990; pp 39– 53.
    Google Scholar
    There is no corresponding record for this reference.
  4. 4
    Akter, F.; Ibanez, J. Chapter 8 - Bone and Cartilage Tissue Engineering. In Tissue Engineering Made Easy; Akter, F., Ed.; Academic Press, 2016; pp 77– 97.
    Google Scholar
    There is no corresponding record for this reference.
  5. 5
    Canadas, R. F.; Pina, S.; Marques, A. P.; Oliveira, J. M.; Reis, R. L. Chapter 7 - Cartilage and Bone Regeneration─How Close Are We to Bedside? In Translating Regenerative Medicine to the Clinic; Laurence, J., Ed.; Academic Press: Boston, 2016; pp 89– 106.
    Google Scholar
    There is no corresponding record for this reference.
  6. 6
    Baldwin, P.; Li, D. J.; Auston, D. A.; Mir, H. S.; Yoon, R. S.; Koval, K. J. Autograft, Allograft, and Bone Graft Substitutes: Clinical Evidence and Indications for Use in the Setting of Orthopaedic Trauma Surgery. J. Orthop. Trauma 2019, 33 (4), 203– 213,  DOI: 10.1097/BOT.0000000000001420
    Google Scholar
    6
    Autograft, Allograft, and Bone Graft Substitutes: Clinical Evidence and Indications for Use in the Setting of Orthopaedic Trauma Surgery
    Baldwin Paul; Koval Kenneth J; Li Deborah J; Auston Darryl A; Mir Hassan S; Yoon Richard S
    Journal of orthopaedic trauma (2019), 33 (4), 203-213 ISSN:.
    Bone grafts are the second most common tissue transplanted in the United States, and they are an essential treatment tool in the field of acute and reconstructive traumatic orthopaedic surgery. Available in cancellous, cortical, or bone marrow aspirate form, autogenous bone graft is regarded as the gold standard in the treatment of posttraumatic conditions such as fracture, delayed union, and nonunion. However, drawbacks including donor-site morbidity and limited quantity of graft available for harvest make autograft a less-than-ideal option for certain patient populations. Advancements in allograft and bone graft substitutes in the past decade have created viable alternatives that circumvent some of the weak points of autografts. Allograft is a favorable alternative for its convenience, abundance, and lack of procurement-related patient morbidity. Options include structural, particulate, and demineralized bone matrix form. Commonly used bone graft substitutes include calcium phosphate and calcium sulfate synthetics-these grafts provide their own benefits in structural support and availability. In addition, different growth factors including bone morphogenic proteins can augment the healing process of bony defects treated with grafts. Autograft, allograft, and bone graft substitutes all possess their own varying degrees of osteogenic, osteoconductive, and osteoinductive properties that make them better suited for different procedures. It is the purpose of this review to characterize these properties and present clinical evidence supporting their indications for use in the hopes of better elucidating treatment options for patients requiring bone grafting in an orthopaedic trauma setting.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3cjgsVSrsA%253D%253D&md5=71bb63d2c6d6af6edfdcc38e5942964c
  7. 7
    Walejewska, E.; Idaszek, J.; Heljak, M.; Chlanda, A.; Choinska, E.; Hasirci, V.; Swieszkowski, W. The Effect of Introduction of Filament Shift on Degradation Behaviour of PLGA- and PLCL-Based Scaffolds Fabricated via Additive Manufacturing. Polym. Degrad. Stab. 2020, 171, 109030  DOI: 10.1016/j.polymdegradstab.2019.109030
    Google Scholar
    7
    The effect of introduction of filament shift on degradation behaviour of PLGA- and PLCL-based scaffolds fabricated via additive manufacturing
    Walejewska, Ewa; Idaszek, Joanna; Heljak, Marcin; Chlanda, Adrian; Choinska, Emilia; Hasirci, Vasif; Swieszkowski, Wojciech
    Polymer Degradation and Stability (2020), 171 (), 109030CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)
    The degrdn. rate of polyester scaffolds has been emphasized as one of the main areas of concern in bone tissue engineering. In ideal conditions, the degrdn. of polymeric constructs should match regeneration of the injured tissue. Thus, there is an imperative need to strictly define and understand determinants influencing the degrdn. rate of scaffolds. In this study, we focused on the effect of filament shift introduction on degrdn. behavior of the polymeric-based scaffolds. The poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ε-caprolactone) (PLCL) and their tricalcium-phosphate-loaded (TCP) composites contg. 20 and 40 wt% of filler, were utilized to fabricate constructs using modified fused deposition modeling (FDM). The scaffolds were designed with filament lay-down pattern of 0°/90° and with or without the modifications of filament distance in n+2 layer, shifted and non-shifted constructs were obtained, resp. To investigate the degrdn. profile, the change of mass, pH, water absorption and initial mol. wt. (Mw0) loss was obsd. during the degrdn. study in phosphate buffered saline (PBS) at 37°C for up to 48 wk. The scaffold morphol. was evaluated utilizing SEM (SEM) and the visualization of the topog. was performed utilizing at. force microscopy (AFM). Surface area to vol. ratio (SVR) and porosity were detd. using micro-computed tomog. (μCT). The fluid flow simulations were used to define the permeability of two investigated groups of scaffolds. The results of this study clearly demonstrate the accelerating effect of filament shift introduction on degrdn. behavior in the scaffolds with similar porosity and SVR. The decrease of Mw0 was significantly higher in case of all shifted samples. We assume that faster degrdn. of shifted constructs may be attributed to their tortuosity, making them less permeable and prone to the degrdn., as the result of the accumulation of acidic products in the tortuous architecture of the samples. Thus, the effect of introduction of filament shift into scaffold architecture comprise an attractive approach to influence the degrdn. rate in case of bone regeneration with the use of polyesters scaffolds.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitlWjsL%252FE&md5=09832fdf27bbe3850d22c5c7d9deef64
  8. 8
    Jaroszewicz, J.; Idaszek, J.; Choinska, E.; Szlazak, K.; Hyc, A.; Osiecka-Iwan, A.; Swieszkowski, W.; Moskalewski, S. Formation of Calcium Phosphate Coatings within Polycaprolactone Scaffolds by Simple, Alkaline Phosphatase Based Method. Mater. Sci. Eng., C 2019, 96, 319– 328,  DOI: 10.1016/j.msec.2018.11.027
    Google Scholar
    8
    Formation of calcium phosphate coatings within polycaprolactone scaffolds by simple, alkaline phosphatase based method
    Jaroszewicz, Jakub; Idaszek, Joanna; Choinska, Emilia; Szlazak, Karol; Hyc, Anna; Osiecka-Iwan, Anna; Swieszkowski, Wojciech; Moskalewski, Stanislaw
    Materials Science & Engineering, C: Materials for Biological Applications (2019), 96 (), 319-328CODEN: MSCEEE; ISSN:0928-4931. (Elsevier B.V.)
    The paper presents a novel approach to the prodn. of calcium phosphate coatings of scaffolds. Mineral deposits were formed during incubation of polycaprolactone (PCL) scaffolds with bovine intestinal alk. phosphatase in sodium glycerophosphate and calcium chloride medium. To modify hydrophobic surface of scaffolds and intensify attachment of coating, scaffolds were incubated at 50°C (thermal activation, TA) or at 37°C after short exposition to lipase (lipase activation, LA). Micro-computed tomog. observations demonstrated that both methods resulted in deposition of mineral on the surface of external and internal walls of the scaffolds. Ppt. formed after thermal and lipase activation contained particles with av. size of 200-400 nm, and the shape of donuts. In thermal activated PCL coatings X-ray diffraction disclosed peaks typical for hydroxyapatite (HAp), while after lipase activation these peaks could be precisely defined only if left for 6 days in the incubation medium. The Fourier-transform IR spectroscopy suggested cryst. structure of HAp both after thermal and lipase activation. The adherence of bone marrow mesenchymal stem cells was initially higher on coated than pristine PCL, but during 7 days of culture the cell no. increased and was similar on all tested samples. Alk. phosphatase activity, considered as a sign of osteogenic differentiation, measured on PCL samples after 7 days was 2-3 times lower on pristine PCL than on the coated samples, but after 2 wk increased significantly and reached similar value as on the calcium phosphate substrates.
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  9. 9
    Idaszek, J.; Bruinink, A.; Święszkowski, W. Ternary Composite Scaffolds with Tailorable Degradation Rate and Highly Improved Colonization by Human Bone Marrow Stromal Cells. J. Biomed. Mater. Res., Part A 2015, 103 (7), 2394– 2404,  DOI: 10.1002/jbm.a.35377
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    9
    Ternary composite scaffolds with tailorable degradation rate and highly improved colonization by human bone marrow stromal cells
    Idaszek, J.; Bruinink, A.; Swieszkowski, W.
    Journal of Biomedical Materials Research, Part A (2015), 103 (7), 2394-2404CODEN: JBMRCH; ISSN:1549-3296. (John Wiley & Sons, Inc.)
    Poly(ε-caprolactone), PCL, is of great interest for fabrication of biodegradable scaffolds due to its high compatibility with various manufg. techniques, esp. Fused Deposition Modeling (FDM). However, slow degrdn. and low strength make application of PCL limited only to longer-term bioresorbable and non-load bearing implants. To overcome latter drawbacks, ternary PCL-based composite fibrous scaffolds consisting of 70-95 wt. % PCL, 5 wt. % Tricalcium Phosphate (TCP) and 0-25 wt. % poly(lactide-co-glycolide) (PLGA) were fabricated using FDM. In the present study, the effect of compn. of the scaffolds on their mech. properties, degrdn. kinetics, and surface properties (wettability, surface energy, and roughness) was investigated and correlated with response of human bone marrow mesenchymal stromal cells (HBMC). The presence of PLGA increased degrdn. kinetics, surface roughness and significantly improved scaffold colonization. Of the evaluated surface properties only the wettability was correlated with the surface area colonized by HBMC. This study demonstrates that introduction of PLGA into PCL-TCP binary composite could largely abolish the disadvantages of the PCL matrix and improve biocompatibility by increasing wettability and polar interactions rather than surface roughness. Addnl., we showed great potential of multicellular spheroids as a sensitive in vitro tool for detection of differences in chem. of 3D scaffolds. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103: 2394-2404, 2015.
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  10. 10
    Bartnikowski, M.; Dargaville, T. R.; Ivanovski, S.; Hutmacher, D. W. Degradation Mechanisms of Polycaprolactone in the Context of Chemistry, Geometry and Environment. Prog. Polym. Sci. 2019, 96, 1– 20,  DOI: 10.1016/j.progpolymsci.2019.05.004
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    10
    Degradation mechanisms of polycaprolactone in the context of chemistry, geometry and environment
    Bartnikowski, Michal; Dargaville, Tim R.; Ivanovski, Saso; Hutmacher, Dietmar W.
    Progress in Polymer Science (2019), 96 (), 1-20CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
    A review, we identify mechanisms of PCL degrdn. across a range of mainly biomedical applications, exploring the role of the polymer structure and form, radical interactions, temp., pH, enzymic activity, and cellular phagocytosis. We examine how polymer chem. has been used to alter PCL degrdn. rates and mechanisms, and present cases where such manipulations may affect the applications of PCL. Significantly, our anal. identifies currently undescribed trends in PCL degrdn. Namely, we observe that mol. wt. decreases at a consistent rate regardless of the initial value, and does so at a linear rate in vitro and an exponential rate in vivo. Both mech. properties and mass loss are strongly influenced by construct geometry and environmental conditions. We further assess the current biomedical literature on the degrdn. of PCL copolymers and its composites. The formation of novel PCL copolymers or composites is often used to broaden the versatility and applicability of the polymer, although this approach is rarely explored beyond initial research. Novel biomaterials overall rarely emerge from research, with inherent issues such as the reproducibility of synthesis, manufg., or characterization methods and outcomes further impeding their translation. We conclude the review with a summary of the current state of the tailorability of PCL-based polymers and composites, and offer recommendations for the future research direction of the field.
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  11. 11
    Florencio-Silva, R.; Sasso, G. R. D. S.; Sasso-Cerri, E.; Simões, M. J.; Cerri, P. S. Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells. BioMed. Res. Int. 2015, 2015, 421746  DOI: 10.1155/2015/421746
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    11
    Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells
    Florencio-Silva Rinaldo; Sasso Gisela Rodrigues da Silva; Simoes Manuel Jesus; Sasso-Cerri Estela; Cerri Paulo Sergio
    BioMed research international (2015), 2015 (), 421746 ISSN:.
    Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.
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  12. 12
    Xiong, Y.; Xiong, Y. Applications of Bone Regeneration Hydrogels in the Treatment of Bone Defects: A Review. J. Mater. Sci. 2022, 57 (2), 887– 913,  DOI: 10.1007/s10853-021-06675-7
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    12
    Applications of bone regeneration hydrogels in the treatment of bone defects: a review
    Xiong, Yukun; Xiong, Yuzhu
    Journal of Materials Science (2022), 57 (2), 887-913CODEN: JMTSAS; ISSN:0022-2461. (Springer)
    A review. Hydrogels can be designed as scaffolds in bone tissue engineering for more efficient healing of bone defects. Bone regeneration hydrogels have attracted extensive attention because of their good biocompatibility and excellent ability in promoting bone regeneration. This review will introduce the methods of bone regeneration hydrogels in the treatment of bone defects. Namely, promoting differentiation and proliferation of osteoblasts, promoting angiogenesis, regulating immune response and promoting mineralization. With the aim to deeply understand the development of bone regeneration hydrogels, we evaluate and summarize its characteristic, so as to help the future research.
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  13. 13
    Chen, J.; Chin, A.; Almarza, A. J.; Taboas, J. M. Hydrogel to Guide Chondrogenesis versus Osteogenesis of Mesenchymal Stem Cells for Fabrication of Cartilaginous Tissues. Biomed. Mater. Bristol Engl. 2020, 15 (4), 045006  DOI: 10.1088/1748-605X/ab401f
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    13
    Hydrogel to guide chondrogenesis versus osteogenesis of mesenchymal stem cells for fabrication of cartilaginous tissues
    Chen Jingming; Chin Adam; Almarza Alejandro J; Taboas Juan M
    Biomedical materials (Bristol, England) (2020), 15 (4), 045006 ISSN:.
    The ideal combination of hydrogel components for regeneration of cartilage and cartilaginous interfaces is a significant challenge because control over differentiation into multiple lineages is necessary. Stabilization of the phenotype of stem cell derived chondrocytes is needed to avoid undesired progression to terminal hypertrophy and tissue mineralization. A novel ternary blend hydrogel composed of methacrylated poly(ethylene glycol) (PEG), gelatin, and heparin (PGH) was designed to guide chondrogenesis by bone marrow derived mesenchymal stem cells (BMSCs) and maintenance of their cartilaginous phenotype. The hydrogel material effects on chondrogenic and osteogenic differentiation by BMSCs were evaluated in comparison to methacrylated gelatin hydrogel (GEL), a conventional bioink used for both chondrogenic and osteogenic applications. PGH and GEL hydrogels were loaded with goat BMSCs and cultured in chondrogenic and osteogenic mediums in vitro over six weeks. The PGH showed no sign of mineral deposition in an osteogenic environment in vitro. To further evaluate material effects, the hydrogels were loaded with adult human BMSCs (hBMSCs) and transforming growth factor β-3 and grown in subcutaneous pockets in mice over eight weeks. Consistent with the in vitro results, the PGH had greater potential to induce chondrogenesis by BMSCs in vivo compared to the GEL as evidenced by elevated gene expression of chondrogenic markers, supporting its potential for stable cartilage engineering. The PGH also showed a greater percentage of GAG positive cells compared to the GEL. Unlike the GEL, the PGH hydrogel exhibited anti-osteogenic effects in vivo as evidenced by negative Von Kossa staining and suppressed gene expression of hypertrophic and osteogenic markers. By nature of their polymer composition alone, the PGH and GEL regulated BMSC differentiation down different osteochondral lineages. Thus, the PGH and GEL are promising hydrogels to regenerate stratified cartilaginous interfacial tissues in situ, such as the mandibular condyle surface, using undifferentiated BMSCs and a stratified scaffold design.
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  14. 14
    Wang, M.; Guo, Y.; Deng, Z.; Xu, P. Engineering Elastic Bioactive Composite Hydrogels for Promoting Osteogenic Differentiation of Embryonic Mesenchymal Stem Cells. Front. Bioeng. Biotechnol. 2022, 10, 1022153  DOI: 10.3389/fbioe.2022.1022153
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    14
    Engineering elastic bioactive composite hydrogels for promoting osteogenic differentiation of embryonic mesenchymal stem cells
    Wang Min; Xu Peng; Guo Yi; Deng Zexing
    Frontiers in bioengineering and biotechnology (2022), 10 (), 1022153 ISSN:2296-4185.
    The development of bioactive materials with good mechanical properties and promotion of stem cell osteogenic differentiation has important application prospects in bone tissue engineering. In this paper, we designed a novel organic-inorganic composite hydrogel (FPIGP@BGN-Sr) utilizing diacrylated F127 (DA-PF127), β-glycerophosphate-modified polyitaconate (PIGP) and strontium-doped bioactive glass nanoparticles (BGN-Sr) through free radical polymerization and coordination interactions and then evaluated its promoting effect on the osteogenic differentiation of mouse embryonic mesenchymal stem cells in detail. The results showed that the FPIGP@BGN-Sr hydrogel exhibited a controlled storage modulus by changing the amount of BGN-Sr. Notably, the FPIGP@BGN-Sr hydrogel possessed excellent elastic ability with a compressive strain of up to 98.6% and negligible change in mechanical properties after 10 cycles of compression. In addition, the FPIGP@BGN-Sr hydrogel had good cytocompatibility, maintained the activity and proliferation of mouse embryonic mesenchymal stem cells (C3H10T1/2), and effectively enhanced the activity of alkaline phosphatase, osteogenic gene expression and biomineralization ability of the cells. In conclusion, the excellent mechanical properties and osteogenic biological activity of the FPIGP@BGN-Sr hydrogel make it a promising organic-inorganic composite bioactive material for stem cell-based bone regeneration.
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  15. 15
    Chen, Z.; Luo, Q.; Lin, C.; Kuang, D.; Song, G. Simulated Microgravity Inhibits Osteogenic Differentiation of Mesenchymal Stem Cells via Depolymerizing F-Actin to Impede TAZ Nuclear Translocation. Sci. Rep. 2016, 6 (1), 30322,  DOI: 10.1038/srep30322
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    15
    Simulated microgravity inhibits osteogenic differentiation of mesenchymal stem cells via depolymerizing F-actin to impede TAZ nuclear translocation
    Chen, Zhe; Luo, Qing; Lin, Chuanchuan; Kuang, Dongdong; Song, Guanbin
    Scientific Reports (2016), 6 (), 30322CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
    Microgravity induces obsd. bone loss in space flight, and reduced osteogenesis of bone mesenchymal stem cells (BMSCs) partly contributes to this phenomenon. Abnormal regulation or functioning of the actin cytoskeleton induced by microgravity may cause the inhibited osteogenesis of BMSCs, but the underlying mechanism remains obscure. In this study, we demonstrated that actin cytoskeletal changes regulate nuclear aggregation of the transcriptional coactivator with PDZ-binding motif (TAZ), which is indispensable for osteogenesis of bone mesenchymal stem cells (BMSCs). Moreover, we utilized a clinostat to model simulated microgravity (SMG) and demonstrated that SMG obviously depolymd. F-actin and hindered TAZ nuclear translocation. Interestingly, stabilizing the actin cytoskeleton induced by Jasplakinolide (Jasp) significantly rescued TAZ nuclear translocation and recovered the osteogenic differentiation of BMSCs in SMG, independently of large tumor suppressor 1(LATS1, an upstream kinase of TAZ). Furthermore, lysophosphatidic acid (LPA) also significantly recovered the osteogenic differentiation of BMSCs in SMG through the F-actin-TAZ pathway. Taken together, we propose that the depolymd. actin cytoskeleton inhibits osteogenic differentiation of BMSCs through impeding nuclear aggregation of TAZ, which provides a novel connection between F-actin cytoskeleton and osteogenesis of BMSCs and has important implications in bone loss caused by microgravity.
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  16. 16
    Luo, T.; Tan, B.; Zhu, L.; Wang, Y.; Liao, J. A Review on the Design of Hydrogels With Different Stiffness and Their Effects on Tissue Repair. Front. Bioeng. Biotechnol. 2022, 10, 817391  DOI: 10.3389/fbioe.2022.817391
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    16
    A Review on the Design of Hydrogels With Different Stiffness and Their Effects on Tissue Repair
    Luo Tianyi; Tan Bowen; Zhu Lengjing; Wang Yating; Liao Jinfeng; Luo Tianyi; Zhu Lengjing; Wang Yating
    Frontiers in bioengineering and biotechnology (2022), 10 (), 817391 ISSN:2296-4185.
    Tissue repair after trauma and infection has always been a difficult problem in regenerative medicine. Hydrogels have become one of the most important scaffolds for tissue engineering due to their biocompatibility, biodegradability and water solubility. Especially, the stiffness of hydrogels is a key factor, which influence the morphology of mesenchymal stem cells (MSCs) and their differentiation. The researches on this point are meaningful to the field of tissue engineering. Herein, this review focus on the design of hydrogels with different stiffness and their effects on the behavior of MSCs. In addition, the effect of hydrogel stiffness on the phenotype of macrophages is introduced, and then the relationship between the phenotype changes of macrophages on inflammatory response and tissue repair is discussed. Finally, the future application of hydrogels with a certain stiffness in regenerative medicine and tissue engineering has been prospected.
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  17. 17
    Discher, D. E.; Janmey, P.; Wang, Y. Tissue Cells Feel and Respond to the Stiffness of Their Substrate. Science 2005, 310 (5751), 1139– 1143,  DOI: 10.1126/science.1116995
    Google Scholar
    17
    Tissue Cells Feel and Respond to the Stiffness of Their Substrate
    Discher, Dennis E.; Janmey, Paul; Wang, Yu-li
    Science (Washington, DC, United States) (2005), 310 (5751), 1139-1143CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
    A review. Normal tissue cells are generally not viable when suspended in a fluid and are therefore said to be anchorage-dependent. Such cells must adhere to a solid, but a solid can be as rigid as glass or softer than a baby's skin. The behavior of some cells on soft materials is characteristic of important phenotypes; for example, cell growth on soft agar gels is used to identify cancer cells. However, an understanding of how tissue cells-including fibroblasts, myocytes, neurons, and other cell types-sense matrix stiffness is just emerging with quant. studies of cells adhering to gels (or to other cells) with which elasticity can be tuned to approx. that of tissues. Key roles in mol. pathways are played by adhesion complexes and the actin-myosin cytoskeleton, whose contractile forces are transmitted through transcellular structures. The feedback of local matrix stiffness on cell state likely has important implications for development, differentiation, disease, and regeneration.
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  18. 18
    Koons, G. L.; Diba, M.; Mikos, A. G. Materials Design for Bone-Tissue Engineering. Nat. Rev. Mater. 2020, 5 (8), 584– 603,  DOI: 10.1038/s41578-020-0204-2
    Google Scholar
    18
    Materials design for bone-tissue engineering
    Koons, Gerry L.; Diba, Mani; Mikos, Antonios G.
    Nature Reviews Materials (2020), 5 (8), 584-603CODEN: NRMADL; ISSN:2058-8437. (Nature Research)
    Abstr.: Successful materials design for bone-tissue engineering requires an understanding of the compn. and structure of native bone tissue, as well as appropriate selection of biomimetic natural or tunable synthetic materials (biomaterials), such as polymers, bioceramics, metals and composites. Scalable fabrication technologies that enable control over construct architecture at multiple length scales, including three-dimensional printing and elec.-field-assisted techniques, can then be employed to process these biomaterials into suitable forms for bone-tissue engineering. In this Review, we provide an overview of materials-design considerations for bone-tissue-engineering applications in both disease modeling and treatment of injuries and disease in humans. We outline the materials-design pathway from implementation strategy through selection of materials and fabrication methods to evaluation. Finally, we discuss unmet needs and current challenges in the development of ideal materials for bone-tissue regeneration and highlight emerging strategies in the field.
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  19. 19
    Annabi, N.; Nichol, J. W.; Zhong, X.; Ji, C.; Koshy, S.; Khademhosseini, A.; Dehghani, F. Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering. Tissue Eng. Part B Rev. 2010, 16 (4), 371– 383,  DOI: 10.1089/ten.teb.2009.0639
    Google Scholar
    19
    Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering
    Annabi, Nasim; Nichol, Jason W.; Zhong, Xia; Ji, Chengdong; Koshy, Sandeep; Khademhosseini, Ali; Dehghani, Fariba
    Tissue Engineering, Part B: Reviews (2010), 16 (4), 371-383CODEN: TEPBAB; ISSN:1937-3368. (Mary Ann Liebert, Inc.)
    A review. Tissue engineering holds great promise for regeneration and repair of diseased tissues, making the development of tissue engineering scaffolds a topic of great interest in biomedical research. Because of their biocompatibility and similarities to native extracellular matrix, hydrogels have emerged as leading candidates for engineered tissue scaffolds. However, precise control of hydrogel properties, such as porosity, remains a challenge. Traditional techniques for creating bulk porosity in polymers have demonstrated success in hydrogels for tissue engineering; however, often the conditions are incompatible with direct cell encapsulation. Emerging technologies have demonstrated the ability to control porosity and the microarchitectural features in hydrogels, creating engineered tissues with structure and function similar to native tissues. In this review, we explore the various technologies for controlling the porosity and microarchitecture within hydrogels, and demonstrate successful applications of combining these techniques.
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  20. 20
    Martinez-Garcia, F. D.; Fischer, T.; Hayn, A.; Mierke, C. T.; Burgess, J. K.; Harmsen, M. C. A Beginner’s Guide to the Characterization of Hydrogel Microarchitecture for Cellular Applications. Gels 2022, 8 (9), 535,  DOI: 10.3390/gels8090535
    Google Scholar
    20
    A Beginner's Guide to the Characterization of Hydrogel Microarchitecture for Cellular Applications
    Martinez-Garcia, Francisco Drusso; Fischer, Tony; Hayn, Alexander; Mierke, Claudia Tanja; Burgess, Janette Kay; Harmsen, Martin Conrad
    Gels (2022), 8 (9), 535CODEN: GELSAZ; ISSN:2310-2861. (MDPI AG)
    A review. The extracellular matrix (ECM) is a three-dimensional, acellular scaffold of living tissues. Incorporating the ECM into cell culture models is a goal of cell biol. studies and requires biocompatible materials that can mimic the ECM. Among such materials are hydrogels: polymeric networks that derive most of their mass from water. With the tuning of their properties, these polymer networks can resemble living tissues. The microarchitectural properties of hydrogels, such as porosity, pore size, fiber length, and surface topol. can det. cell plasticity. The adequate characterization of these parameters requires reliable and reproducible methods. However, most methods were historically standardized using other biol. specimens, such as 2D cell cultures, biopsies, or even animal models. Therefore, their translation comes with tech. limitations when applied to hydrogel-based cell culture systems. In our current work, we have reviewed the most common techniques employed in the characterization of hydrogel microarchitectures. Our review provides a concise description of the underlying principles of each method and summarizes the collective data obtained from cell-free and cell-loaded hydrogels. The advantages and limitations of each technique are discussed, and comparisons are made. The information presented in our current work will be of interest to researchers who employ hydrogels as platforms for cell culture, 3D bioprinting, and other fields within hydrogel-based research.
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  21. 21
    Klotz, B. J.; Gawlitta, D.; Rosenberg, A. J. W. P.; Malda, J.; Melchels, F. P. W. Gelatin-Methacryloyl Hydrogels: Towards Biofabrication-Based Tissue Repair. Trends Biotechnol. 2016, 34 (5), 394– 407,  DOI: 10.1016/j.tibtech.2016.01.002
    Google Scholar
    21
    Gelatin-Methacryloyl Hydrogels: Towards Biofabrication-Based Tissue Repair
    Klotz, Barbara J.; Gawlitta, Debby; Rosenberg, Antoine J. W. P.; Malda, Jos; Melchels, Ferry P. W.
    Trends in Biotechnology (2016), 34 (5), 394-407CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)
    Research over the past decade on the cell-biomaterial interface has shifted to the third dimension. Besides mimicking the native extracellular environment by 3D cell culture, hydrogels offer the possibility to generate well-defined 3D biofabricated tissue analogs. In this context, gelatin-methacryloyl (gelMA) hydrogels have recently gained increased attention. This interest is sparked by the combination of the inherent bioactivity of gelatin and the physicochem. tailorability of photo-crosslinkable hydrogels. GelMA is a versatile matrix that can be used to engineer tissue analogs ranging from vasculature to cartilage and bone. Convergence of biol. and biofabrication approaches is necessary to progress from merely proving cell functionality or construct shape fidelity towards regenerating tissues. GelMA has a crit. pioneering role in this process and could be used to accelerate the development of clin. relevant applications.
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  22. 22
    Lim, K. S.; Klotz, B. J.; Lindberg, G. C. J.; Melchels, F. P. W.; Hooper, G. J.; Malda, J.; Gawlitta, D.; Woodfield, T. B. F. Visible Light Cross-Linking of Gelatin Hydrogels Offers an Enhanced Cell Microenvironment with Improved Light Penetration Depth. Macromol. Biosci. 2019, 19 (6), e1900098  DOI: 10.1002/mabi.201900098
    Google Scholar
    There is no corresponding record for this reference.
  23. 23
    Van Den Bulcke, A. I.; Bogdanov, B.; De Rooze, N.; Schacht, E. H.; Cornelissen, M.; Berghmans, H. Structural and Rheological Properties of Methacrylamide Modified Gelatin Hydrogels. Biomacromolecules 2000, 1 (1), 31– 38,  DOI: 10.1021/bm990017d
    Google Scholar
    23
    Structural and Rheological Properties of Methacrylamide Modified Gelatin Hydrogels
    Van Den Bulcke, An I.; Bogdanov, Bogdan; De Rooze, Nadine; Schacht, Etienne H.; Cornelissen, Maria; Berghmans, Hugo
    Biomacromolecules (2000), 1 (1), 31-38CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)
    Dynamic shear oscillation measurements at small strain were used to characterize the viscoelastic properties and related differences in the mol. structure of hydrogels based on gelatin methacrylamide. Gelatin was derivatized with methacrylamide side groups and was subsequently cross-linked by radical polymn. via photoinitiation. The light treatment of methacrylamide gelatin solns. resulted in the prodn. of hydrogel films with high storage modulus (G'). Mech. spectra and thermal scanning rheol. of the obtained hydrogels are described. The temp. scan of the network below and above m.p. of gelatin allowed us to identify the resp. contributions of chem. and phys. cross-linkage to the hydrogel elastic modulus. The results indicate that the rheol. properties of the gelatin-based hydrogels can be controlled by the degree of substitution, polymer concn., initiator concn., and UV irradn. conditions.
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  24. 24
    He, J.; Sun, Y.; Gao, Q.; He, C.; Yao, K.; Wang, T.; Xie, M.; Yu, K.; Nie, J.; Chen, Y.; He, Y. Gelatin Methacryloyl Hydrogel, from Standardization, Performance, to Biomedical Application. Adv. Healthc. Mater. 2023, 12 (23), 2300395  DOI: 10.1002/adhm.202300395
    Google Scholar
    24
    Gelatin Methacryloyl Hydrogel, from Standardization, Performance, to Biomedical Application
    He, Jing; Sun, Yuan; Gao, Qing; He, Chanfan; Yao, Ke; Wang, Tongyao; Xie, Mingjun; Yu, Kang; Nie, Jing; Chen, Yuewei; He, Yong
    Advanced Healthcare Materials (2023), 12 (23), 2300395CODEN: AHMDBJ; ISSN:2192-2640. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Gelatin methacryloyl (GelMA), a photocurable hydrogel, is widely used in 3D culture, particularly in 3D bioprinting, due to its high biocompatibility, tunable physicochem. properties, and excellent formability. However, as the properties and performances of GelMA vary under different synthetic conditions, there is a lack of standardization, leading to conflicting results. In this study, a uniform std. is established to understand and enhance GelMA applications. First, the basic concept of GelMA and the d. of the mol. network (DMN) are defined. Second, two properties, degrees of substitution and ratio of solid content, as the main measurable parameters detg. the DMN are used. Third, the mechanisms and relationships between DMN and its performance in various applications in terms of porosity, viscosity, formability, mech. strength, swelling, biodegrdn., and cytocompatibility are theor. explained. The main questions that are answered: what does performance mean, why is it important, how to optimize the basic parameters to improve the performance, and how to characterize it reasonably and accurately. Finally, it is hoped that this knowledge will eliminate the need for researchers to conduct tedious and repetitive pre-expts., enable easy communication for achievements between groups under the same std., and fully explore the potential of the GelMA hydrogel.
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  25. 25
    Yue, K.; Trujillo-de Santiago, G.; Alvarez, M. M.; Tamayol, A.; Annabi, N.; Khademhosseini, A. Synthesis, Properties, and Biomedical Applications of Gelatin Methacryloyl (GelMA) Hydrogels. Biomaterials 2015, 73, 254– 271,  DOI: 10.1016/j.biomaterials.2015.08.045
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    25
    Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels
    Yue, Kan; Trujillo-de Santiago, Grissel; Alvarez, Mario Moises; Tamayol, Ali; Annabi, Nasim; Khademhosseini, Ali
    Biomaterials (2015), 73 (), 254-271CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
    A review. Gelatin methacryloyl (GelMA) hydrogels have been widely used for various biomedical applications due to their suitable biol. properties and tunable phys. characteristics. GelMA hydrogels closely resemble some essential properties of native extracellular matrix (ECM) due to the presence of cell-attaching and matrix metalloproteinase responsive peptide motifs, which allow cells to proliferate and spread in GelMA-based scaffolds. GelMA is also versatile from a processing perspective. It crosslinks when exposed to light irradn. to form hydrogels with tunable mech. properties. It can also be microfabricated using different methodologies including micromolding, photomasking, bioprinting, self-assembly, and microfluidic techniques to generate constructs with controlled architectures. Hybrid hydrogel systems can also be formed by mixing GelMA with nanoparticles such as carbon nanotubes and graphene oxide, and other polymers to form networks with desired combined properties and characteristics for specific biol. applications. Recent research has demonstrated the proficiency of GelMA-based hydrogels in a wide range of tissue engineering applications including engineering of bone, cartilage, cardiac, and vascular tissues, among others. Other applications of GelMA hydrogels, besides tissue engineering, include fundamental cell research, cell signaling, drug and gene delivery, and bio-sensing.
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  26. 26
    Young, A. T.; White, O. C.; Daniele, M. A. Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels. Macromol. Biosci. 2020, 20 (12), e2000183  DOI: 10.1002/mabi.202000183
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    26
    Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels
    Young, Ashlyn T.; White, Olivia C.; Daniele, Michael A.
    Macromolecular Bioscience (2020), 20 (12), 2000183CODEN: MBAIBU; ISSN:1616-5187. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Synthetically modified proteins, such as gelatin methacryloyl (GelMA), are growing in popularity for bioprinting and biofabrication. GelMA is a photocurable macromer that can rapidly form hydrogels, while also presenting bioactive peptide sequences for cellular adhesion and proliferation. The mech. properties of GelMA are highly tunable by modifying the degree of substitution via synthesis conditions, though the effects of source material and thermal gelation have not been comprehensively characterized for lower concn. gels. Herein, the effects of animal source and processing sequence are investigated on scaffold mech. properties. Hydrogels of 4-6 wt% are characterized. Depending on the temp. at crosslinking, the storage moduli for GelMA derived from pigs, cows, and cold-water fish range from 723 to 7340 Pa, 516 to 3484 Pa, and 294 to 464 Pa, resp. The max. storage moduli are achieved only by coordinated phys. gelation and chem. crosslinking. In this method, the classic thermo-reversible gelation of gelatin occurs when GelMA is cooled below a thermal transition temp., which is subsequently 'locked in' by chem. crosslinking via photocuring. The effects of coordinated phys. gelation and chem. crosslinking are demonstrated by precise photopatterning of cell-laden microstructures, inducing different cellular behavior depending on the selected mech. properties of GelMA.
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  27. 27
    Chansoria, P.; Asif, S.; Polkoff, K.; Chung, J.; Piedrahita, J. A.; Shirwaiker, R. A. Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GelMA) Hydrogels. ACS Biomater. Sci. Eng. 2021, 7 (11), 5175– 5188,  DOI: 10.1021/acsbiomaterials.1c00635
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    27
    Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GelMA) Hydrogels
    Chansoria, Parth; Asif, Suleman; Polkoff, Kathryn; Chung, Jaewook; Piedrahita, Jorge A.; Shirwaiker, Rohan A.
    ACS Biomaterials Science & Engineering (2021), 7 (11), 5175-5188CODEN: ABSEBA; ISSN:2373-9878. (American Chemical Society)
    Gelatin methacryloyl (GelMA) hydrogels have emerged as promising and versatile biomaterial matrixes with applications spanning drug delivery, disease modeling, and tissue engineering and regenerative medicine. GelMA exhibits reversible thermal crosslinking at temps. below 37°C due to the entanglement of constitutive polymeric chains, and subsequent UV photo-crosslinking can covalently bind neighboring chains to create irreversibly cross-linked hydrogels. However, how these crosslinking modalities interact and can be modulated during biofabrication to control the structural and functional characteristics of this versatile biomaterial is not well explored yet. Accordingly, this work characterizes the effects of synergistic thermal and photo-crosslinking as a function of GelMA soln. temp. and UV photo-crosslinking duration during biofabrication on the hydrogels' stiffness, microstructure, proteolytic degrdn., and responses of NIH 3T3 and human adipose-derived stem cells (hASC). Smaller pore size, lower degrdn. rate, and increased stiffness are reported in hydrogels processed at lower temp. or prolonged UV exposure. In hydrogels with low stiffness, the cells were found to shear the matrix and cluster into microspheroids, while poor cell attachment was noted in high stiffness hydrogels. In hydrogels with moderate stiffness, ones processed at lower temp. demonstrated better shape fidelity and cell proliferation over time. Anal. of gene expression of hASC encapsulated within the hydrogels showed that, while the GelMA matrix assisted in maintenance of stem cell phenotype (CD44), a higher matrix stiffness resulted in higher pro-inflammatory marker (ICAM1) and markers for cell-matrix interaction (ITGA1 and ITGA10). Anal. of constructs with ultrasonically patterned hASC showed that hydrogels processed at higher temp. possessed lower structural fidelity but resulted in more cell elongation and greater anisotropy over time. These findings demonstrate the significant impact of GelMA material formulation and processing conditions on the structural and functional properties of the hydrogels. The understanding of these material-process-structure-function interactions is crit. toward optimizing the functional properties of GelMA hydrogels for different targeted applications.
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  28. 28
    Ying, G.-L.; Jiang, N.; Maharjan, S.; Yin, Y.-X.; Chai, R.-R.; Cao, X.; Yang, J.-Z.; Miri, A. K.; Hassan, S.; Zhang, Y. S. Aqueous Two-Phase Emulsion Bioink-Enabled 3D Bioprinting of Porous Hydrogels. Adv. Mater. Deerfield Beach Fla 2018, 30 (50), e1805460  DOI: 10.1002/adma.201805460
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    There is no corresponding record for this reference.
  29. 29
    Khattak, S. F.; Bhatia, S. R.; Roberts, S. C. Pluronic F127 as a Cell Encapsulation Material: Utilization of Membrane-Stabilizing Agents. Tissue Eng. 2005, 11 (5–6), 974– 983,  DOI: 10.1089/ten.2005.11.974
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    29
    Pluronic F127 as a Cell Encapsulation Material: Utilization of Membrane-Stabilizing Agents
    Khattak, Sarwat F.; Bhatia, Surita R.; Roberts, Susan C.
    Tissue Engineering (2005), 11 (5/6), 974-983CODEN: TIENFP; ISSN:1076-3279. (Mary Ann Liebert, Inc.)
    Thermoreversible gelation of the copolymer Pluronic F127 (generic name, poloxamer 407) in water makes it a unique candidate for cell encapsulation applications, either alone or to promote cell seeding and attachment in tissue scaffolds. At concns. of 15-20% (wt./wt.), aq. Pluronic F127 (F127) solns. gel at physiol. temps. The effect of F127 on viability and proliferation of human liver carcinoma cells (HepG2) was detd. for both liq. and gel formulations. Cell concn. and viability over a 5-day period were measured by the trypan blue assay via hemocytometry and results were confirmed in both the MTT and LDH assays. With 0.1-5% (wt./wt.) F127 (liq.), cells proliferated and maintained high viability over 5 days. However, at 10% (wt./wt.) F127 (liq.), there was a significant decrease in cell viability and no cell proliferation was evident. HepG2 cell encapsulation in F127 concns. ranging from 15 to 20% (wt./wt.) (gel) resulted in complete cell death by 5 days. This was also true for the HMEC-1 (endothelial) and L6 (muscle) cell lines evaluated. Cell-seeding d. did not affect cell survival or proliferation. Membrane-stabilizing agents (hydrocortisone, glucose, and glycerol) were added to the F127 gel formulations to improve cell viability. The steroid hydrocortisone demonstrated the most significant improvement in viability, from <2% (in F127 alone) to >70% (with 60 nM hydrocortisone added). These results suggest that F127 formulations supplemented with membrane-stabilizing agents can serve as viable cell encapsulation materials. In addn., hydrocortisone may be generally useful in the promotion of cell viability for a wide range of encapsulation materials.
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  30. 30
    Gioffredi, E.; Boffito, M.; Calzone, S.; Giannitelli, S. M.; Rainer, A.; Trombetta, M.; Mozetic, P.; Chiono, V. Pluronic F127 Hydrogel Characterization and Biofabrication in Cellularized Constructs for Tissue Engineering Applications. Procedia CIRP 2016, 49, 125– 132,  DOI: 10.1016/j.procir.2015.11.001
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    There is no corresponding record for this reference.
  31. 31
    García-Couce, J.; Tomás, M.; Fuentes, G.; Que, I.; Almirall, A.; Cruz, L. J. Chitosan/Pluronic F127 Thermosensitive Hydrogel as an Injectable Dexamethasone Delivery Carrier. Gels Basel Switz. 2022, 8 (1), 44,  DOI: 10.3390/gels8010044
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    There is no corresponding record for this reference.
  32. 32
    Gong, J.; Schuurmans, C. C. L.; van Genderen, A. M.; Cao, X.; Li, W.; Cheng, F.; He, J. J.; López, A.; Huerta, V.; Manríquez, J.; Li, R.; Li, H.; Delavaux, C.; Sebastian, S.; Capendale, P. E.; Wang, H.; Xie, J.; Yu, M.; Masereeuw, R.; Vermonden, T.; Zhang, Y. S. Complexation-Induced Resolution Enhancement of 3D-Printed Hydrogel Constructs. Nat. Commun. 2020, 11 (1), 1267  DOI: 10.1038/s41467-020-14997-4
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    32
    Complexation-induced resolution enhancement of 3D-printed hydrogel constructs
    Gong, Jiaxing; Schuurmans, Carl C. L.; van Genderen, Anne Metje; Cao, Xia; Li, Wanlu; Cheng, Feng; He, Jacqueline Jialu; Lopez, Arturo; Huerta, Valentin; Manriquez, Jennifer; Li, Ruiquan; Li, Hongbin; Delavaux, Clement; Sebastian, Shikha; Capendale, Pamela E.; Wang, Huiming; Xie, Jingwei; Yu, Mengfei; Masereeuw, Rosalinde; Vermonden, Tina; Zhang, Yu Shrike
    Nature Communications (2020), 11 (1), 1267CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
    Three-dimensional (3D) hydrogel printing enables prodn. of volumetric architectures contg. desired structures using programmed automation processes. Our study reports a unique method of resoln. enhancement purely relying on post-printing treatment of hydrogel constructs. By immersing a 3D-printed patterned hydrogel consisting of a hydrophilic polyionic polymer network in a soln. of polyions of the opposite net charge, shrinking can rapidly occur resulting in various degrees of reduced dimensions comparing to the original pattern. This phenomenon, caused by complex coacervation and water expulsion, enables us to reduce linear dimensions of printed constructs while maintaining cytocompatible conditions in a cell type-dependent manner. We anticipate our shrinking printing technol. to find widespread applications in promoting the current 3D printing capacities for generating higher-resoln. hydrogel-based structures without necessarily having to involve complex hardware upgrades or other printing parameter alterations.
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  33. 33
    Ying, G.; Jiang, N.; Parra-Cantu, C.; Tang, G.; Zhang, J.; Wang, H.; Chen, S.; Huang, N.-P.; Xie, J.; Zhang, Y. S. Bioprinted Injectable Hierarchically Porous Gelatin Methacryloyl Hydrogel Constructs with Shape-Memory Properties. Adv. Funct. Mater. 2020, 30 (46), 2003740  DOI: 10.1002/adfm.202003740
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    33
    Bioprinted Injectable Hierarchically Porous Gelatin Methacryloyl Hydrogel Constructs with Shape-Memory Properties
    Ying, Guoliang; Jiang, Nan; Parra-Cantu, Carolina; Tang, Guosheng; Zhang, Jingyi; Wang, Hongjun; Chen, Shixuan; Huang, Ning-Ping; Xie, Jingwei; Zhang, Yu Shrike
    Advanced Functional Materials (2020), 30 (46), 2003740CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    Direct injection of cell-laden hydrogels shows high potential for tissue regeneration in translational therapy. The traditional cell-laden hydrogels are often used as bulk space fillers to tissue defects after injection, likely limiting their structural controllability. On the other hand, patterned cell-laden hydrogel constructs often necessitate invasive surgical procedures. To overcome these problems, herein, a unique strategy is reported for encapsulating living human cells in a pore-forming gelatin methacryloyl (GelMA)-based bioink to ultimately produce injectable hierarchically macro-micro-nanoporous cell-laden GelMA hydrogel constructs through 3D extrusion bioprinting. The hydrogel constructs can be fabricated into various shapes and sizes that are defect-specific. Due to the hierarchically macro-micro-nanoporous structures, the cell-laden hydrogel constructs can readily recover to their original shapes, and sustain high cell viability, proliferation, spreading, and differentiation after compression and injection. In addn., in vivo studies further reveal that the hydrogel constructs can integrate well with the surrounding host tissues. These findings suggest that the unique 3D-bioprinted pore-forming GelMA hydrogel constructs are promising candidates for applications in minimally invasive tissue regeneration and cell therapy.
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  34. 34
    Ying, G.; Manríquez, J.; Wu, D.; Zhang, J.; Jiang, N.; Maharjan, S.; Hernández Medina, D. H.; Zhang, Y. S. An Open-Source Handheld Extruder Loaded with Pore-Forming Bioink for in Situ Wound Dressing. Mater. Today Bio 2020, 8, 100074  DOI: 10.1016/j.mtbio.2020.100074
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    34
    An open-source handheld extruder loaded with pore-forming bioink for in situ wound dressing
    Ying G; Manriquez J; Wu D; Zhang J; Maharjan S; Hernandez Medina D H; Zhang Y S; Jiang N
    Materials today. Bio (2020), 8 (), 100074 ISSN:.
    The increasing demand in rapid wound dressing and healing has promoted the development of intraoperative strategies, such as intraoperative bioprinting, which allows deposition of bioinks directly at the injury sites to conform to their specific shapes and structures. Although successes have been achieved to varying degrees, either the instrumentation remains complex and high-cost or the bioink is insufficient for desired cellular activities. Here, we report the development of a cost-effective, open-source handheld bioprinter featuring an ergonomic design, which was entirely portable powered by a battery pack. We further integrated an aqueous two-phase emulsion bioink based on gelatin methacryloyl with the handheld system, enabling convenient shape-controlled in situ bioprinting. The unique pore-forming property of the emulsion bioink facilitated liquid and oxygen transport as well as cellular proliferation and spreading, with an additional ability of good elasticity to withstand repeated mechanical compressions. These advantages of our pore-forming bioink-loaded handheld bioprinter are believed to pave a new avenue for effective wound dressing potentially in a personalized manner down the future.
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  35. 35
    Loessner, D.; Meinert, C.; Kaemmerer, E.; Martine, L. C.; Yue, K.; Levett, P. A.; Klein, T. J.; Melchels, F. P. W.; Khademhosseini, A.; Hutmacher, D. W. Functionalization, Preparation and Use of Cell-Laden Gelatin Methacryloyl–Based Hydrogels as Modular Tissue Culture Platforms. Nat. Protoc. 2016, 11 (4), 727– 746,  DOI: 10.1038/nprot.2016.037
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    35
    Functionalization, preparation and use of cell-laden gelatin methacryloyl-based hydrogels as modular tissue culture platforms
    Loessner, Daniela; Meinert, Christoph; Kaemmerer, Elke; Martine, Laure C.; Yue, Kan; Levett, Peter A.; Klein, Travis J.; Melchels, Ferry P. W.; Khademhosseini, Ali; Hutmacher, Dietmar W.
    Nature Protocols (2016), 11 (4), 727-746CODEN: NPARDW; ISSN:1750-2799. (Nature Publishing Group)
    Progress in advancing a system-level understanding of the complexity of human tissue development and regeneration is hampered by a lack of biol. model systems that recapitulate key aspects of these processes in a physiol. context. Hence, growing demand by cell biologists for organ-specific extracellular mimics has led to the development of a plethora of 3D cell culture assays based on natural and synthetic matrixes. We developed a physiol. microenvironment of semisynthetic origin, called gelatin methacryloyl (GelMA)-based hydrogels, which combine the biocompatibility of natural matrixes with the reproducibility, stability and modularity of synthetic biomaterials. We describe here a step-by-step protocol for the prepn. of the GelMA polymer, which takes 1-2 wk to complete, and which can be used to prep. hydrogel-based 3D cell culture models for cancer and stem cell research, as well as for tissue engineering applications. We also describe quality control and validation procedures, including how to assess the degree of GelMA functionalization and mech. properties, to ensure reproducibility in exptl. and animal studies.
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  36. 36
    Celikkin, N.; Mastrogiacomo, S.; Jaroszewicz, J.; Walboomers, X. F.; Swieszkowski, W. Gelatin Methacrylate Scaffold for Bone Tissue Engineering: The Influence of Polymer Concentration. J. Biomed. Mater. Res., Part A 2018, 106 (1), 201– 209,  DOI: 10.1002/jbm.a.36226
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    36
    Gelatin methacrylate scaffold for bone tissue engineering: The influence of polymer concentration
    Celikkin, Nehar; Mastrogiacomo, Simone; Jaroszewicz, Jakub; Walboomers, X. Frank; Swieszkowski, Wojciech
    Journal of Biomedical Materials Research, Part A (2018), 106 (1), 201-209CODEN: JBMRCH; ISSN:1549-3296. (John Wiley & Sons, Inc.)
    Gelatin methacrylate (GelMA) is an inexpensive, photocrosslinkable, cell-responsive hydrogel which has drawn attention for a wide range of tissue engineering applications. The potential of GelMA scaffolds was demonstrated to be tunable for different tissue engineering (TE) applications through modifying the polymer concn., methacrylation degree, or UV light intensity. Despite the promising results of GelMA hydrogels in tissue engineering, the influence of polymer concn. for bone tissue engineering (BTE) scaffolds was not established yet. Thus, in this study, we have demonstrated the effect of polymer concn. in GelMA scaffolds on osteogenic differentiation. We prepd. GelMA scaffolds with 5 and 10% polymer concns. and characterized the scaffolds in terms of porosity, pore size, swelling characteristics, and mech. properties. Subsequent to the scaffolds characterization, the scaffolds were seeded with bone marrow derived rat mesenchymal stem cells and cultured in osteogenic media to evaluate the possible osteogenic differentiation effect exerted by the polymer concn. After 7, 14, 21, and 28 days, DNA content, calcium deposition, and alk. phosphatase (ALP) activity of scaffolds were evaluated quant. by colorimetric bioassays. Furthermore, the distribution of the calcium deposition within the scaffolds was attained qual. and quant. by microcomputer tomog. (μCT). Our data suggest that GelMA hydrogels prepd. with 5% polymer concn. has promoted homogeneous extracellular matrix calcification and it is a great candidate for BTE applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017.
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  37. 37
    Cao, X.; Ashfaq, R.; Cheng, F.; Maharjan, S.; Li, J.; Ying, G.; Hassan, S.; Xiao, H.; Yue, K.; Zhang, Y. S. A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair. Adv. Funct. Mater. 2023, 33 (33), 2307408  DOI: 10.1002/adfm.202307408
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    37
    A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair
    Cao, Xia; Ashfaq, Ramla; Cheng, Feng; Maharjan, Sushila; Li, Jun; Ying, Guoliang; Hassan, Shabir; Xiao, Haiyan; Yue, Kan; Zhang, Yu Shrike
    Advanced Functional Materials (2023), 33 (33), 2307408CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    There is no expanded citation for this reference.
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  38. 38
    Byambaa, B.; Annabi, N.; Yue, K.; Trujillo-de Santiago, G.; Alvarez, M. M.; Jia, W.; Kazemzadeh-Narbat, M.; Shin, S. R.; Tamayol, A.; Khademhosseini, A. Bioprinted Osteogenic and Vasculogenic Patterns for Engineering 3D Bone Tissue. Adv. Healthc. Mater. 2017, 6 (16), 1700015  DOI: 10.1002/adhm.201700015
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    There is no corresponding record for this reference.
  39. 39
    Claaßen, C.; Claaßen, M. H.; Truffault, V.; Sewald, L.; Tovar, G. E. M.; Borchers, K.; Southan, A. Quantification of Substitution of Gelatin Methacryloyl: Best Practice and Current Pitfalls. Biomacromolecules 2018, 19 (1), 42– 52,  DOI: 10.1021/acs.biomac.7b01221
    Google Scholar
    39
    Quantification of Substitution of Gelatin Methacryloyl: Best Practice and Current Pitfalls
    Claassen, Christiane; Claassen, Marc H.; Truffault, Vincent; Sewald, Lisa; Tovar, Guenter E. M.; Borchers, Kirsten; Southan, Alexander
    Biomacromolecules (2018), 19 (1), 42-52CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)
    Crosslinkable gelatin methacryloyl (GM) is widely used for the generation of artificial extracellular matrix (ECM) in tissue engineering. However, the quantification of modified groups in GM is still an unsolved issue, although this is the key factor for tailoring the physicochem. material properties. In this contribution, 1H-13C-HSQC NMR spectra are used to gain detailed structural information on GMs and of 2-fold modified gelatin contg. methacryloyl and acetyl groups (GMAs). Distinctive identification of methacrylate, methacrylamide, and acetyl groups present in GMs and GMAs revealed an overlap of methacrylamide and modified hydroxyproline signals in the 1H NMR spectrum. Considering this, we suggest a method to quantify methacrylate and methacrylamide groups in GMs precisely based on simple 1H NMR spectroscopy with an internal std. Quantification of acetylation in GMAs is also possible, yet, 2D NMR spectra are necessary. The described methods allow direct quantification of modified groups in gelatin derivs., making them superior to other, indirect methods known so far.
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  40. 40
    Engler, A. J.; Sen, S.; Sweeney, H. L.; Discher, D. E. Matrix Elasticity Directs Stem Cell Lineage Specification. Cell 2006, 126 (4), 677– 689,  DOI: 10.1016/j.cell.2006.06.044
    Google Scholar
    40
    Matrix elasticity directs stem cell lineage specification
    Engler, Adam J.; Sen, Shamik; Sweeney, H. Lee; Discher, Dennis E.
    Cell (Cambridge, MA, United States) (2006), 126 (4), 677-689CODEN: CELLB5; ISSN:0092-8674. (Cell Press)
    Microenvironments appear important in stem cell lineage specification but can be difficult to adequately characterize or control with soft tissues. Naive mesenchymal stem cells (MSCs) are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity. Soft matrixes that mimic brain are neurogenic, stiffer matrixes that mimic muscle are myogenic, and comparatively rigid matrixes that mimic collagenous bone prove osteogenic. During the initial week in culture, reprogramming of these lineages is possible with addn. of sol. induction factors, but after several weeks in culture, the cells commit to the lineage specified by matrix elasticity, consistent with the elasticity-insensitive commitment of differentiated cell types. Inhibition of nonmuscle myosin II blocks all elasticity-directed lineage specification-without strongly perturbing many other aspects of cell function and shape. The results have significant implications for understanding phys. effects of the in vivo microenvironment and also for therapeutic uses of stem cells.
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  41. 41
    Chen, Y.-C.; Lin, R.-Z.; Qi, H.; Yang, Y.; Bae, H.; Melero-Martin, J. M.; Khademhosseini, A. Functional Human Vascular Network Generated in Photocrosslinkable Gelatin Methacrylate Hydrogels. Adv. Funct. Mater. 2012, 22 (10), 2027– 2039,  DOI: 10.1002/adfm.201101662
    Google Scholar
    41
    Functional Human Vascular Network Generated in Photocrosslinkable Gelatin Methacrylate Hydrogels
    Chen, Ying-Chieh; Lin, Ruei-Zeng; Qi, Hao; Yang, Yunzhi; Bae, Hojae; Melero-Martin, Juan M.; Khademhosseini, Ali
    Advanced Functional Materials (2012), 22 (10), 2027-2039CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
    The generation of functional, 3D vascular networks is a fundamental prerequisite for the development of many future tissue engineering-based therapies. Current approaches in vascular network bioengineering are largely carried out using natural hydrogels as embedding scaffolds. However, most natural hydrogels present a poor mech. stability and a suboptimal durability, which are crit. limitations that hamper their widespread applicability. The search for improved hydrogels has become a priority in tissue engineering research. Here, the suitability of a photopolymerizable gelatin methacrylate (GelMA) hydrogel to support human progenitor cell-based formation of vascular networks is demonstrated. Using GelMA as the embedding scaffold, it is shown that 3D constructs contg. human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSCs) generate extensive capillary-like networks in vitro. These vascular structures contain distinct lumens that are formed by the fusion of ECFC intracellular vacuoles in a process of vascular morphogenesis. The process of vascular network formation is dependent on the presence of MSCs, which differentiate into perivascular cells occupying abluminal positions within the network. Importantly, it is shown that implantation of cell-laden GelMA hydrogels into immunodeficient mice results in a rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, it is shown that the degree of methacrylation of the GelMA can be used to modulate the cellular behavior and the extent of vascular network formation both in vitro and in vivo. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.
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  42. 42
    Nichol, J. W.; Koshy, S. T.; Bae, H.; Hwang, C. M.; Yamanlar, S.; Khademhosseini, A. Cell-Laden Microengineered Gelatin Methacrylate Hydrogels. Biomaterials 2010, 31 (21), 5536– 5544,  DOI: 10.1016/j.biomaterials.2010.03.064
    Google Scholar
    42
    Cell-laden microengineered gelatin methacrylate hydrogels
    Nichol, Jason W.; Koshy, Sandeep T.; Bae, Hojae; Hwang, Chang M.; Yamanlar, Seda; Khademhosseini, Ali
    Biomaterials (2010), 31 (21), 5536-5544CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
    The cellular microenvironment plays an integral role in improving the function of microengineered tissues. Control of the microarchitecture in engineered tissues can be achieved through photopatterning of cell-laden hydrogels. However, despite high pattern fidelity of photopolymerizable hydrogels, many such materials are not cell-responsive and have limited biodegradability. Here, the authors demonstrate gelatin methacrylate (GelMA) as an inexpensive, cell-responsive hydrogel platform for creating cell-laden microtissues and microfluidic devices. Cells readily bound to, proliferated, elongated, and migrated both when seeded on micropatterned GelMA substrates as well as when encapsulated in microfabricated GelMA hydrogels. The hydration and mech. properties of GelMA were demonstrated to be tunable for various applications through modification of the methacrylation degree and gel concn. The pattern fidelity and resoln. of GelMA were high and it could be patterned to create perfusable microfluidic channels. Furthermore, GelMA micropatterns could be used to create cellular micropatterns for in vitro cell studies or 3D microtissue fabrication. These data suggest that GelMA hydrogels could be useful for creating complex, cell-responsive microtissues, such as endothelialized microvasculature, or for other applications that require cell-responsive microengineered hydrogels.
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  43. 43
    Malda, J.; Visser, J.; Melchels, F. P.; Jüngst, T.; Hennink, W. E.; Dhert, W. J. A.; Groll, J.; Hutmacher, D. W. 25th Anniversary Article: Engineering Hydrogels for Biofabrication. Adv. Mater. Deerfield Beach Fla 2013, 25 (36), 5011– 5028,  DOI: 10.1002/adma.201302042
    Google Scholar
    43
    25th anniversary article: Engineering hydrogels for biofabrication
    Malda Jos; Visser Jetze; Melchels Ferry P; Jungst Tomasz; Hennink Wim E; Dhert Wouter J A; Groll Jurgen; Hutmacher Dietmar W
    Advanced materials (Deerfield Beach, Fla.) (2013), 25 (36), 5011-28 ISSN:.
    With advances in tissue engineering, the possibility of regenerating injured tissue or failing organs has become a realistic prospect for the first time in medical history. Tissue engineering - the combination of bioactive materials with cells to generate engineered constructs that functionally replace lost and/or damaged tissue - is a major strategy to achieve this goal. One facet of tissue engineering is biofabrication, where three-dimensional tissue-like structures composed of biomaterials and cells in a single manufacturing procedure are generated. Cell-laden hydrogels are commonly used in biofabrication and are termed "bioinks". Hydrogels are particularly attractive for biofabrication as they recapitulate several features of the natural extracellular matrix and allow cell encapsulation in a highly hydrated mechanically supportive three-dimensional environment. Additionally, they allow for efficient and homogeneous cell seeding, can provide biologically-relevant chemical and physical signals, and can be formed in various shapes and biomechanical characteristics. However, despite the progress made in modifying hydrogels for enhanced bioactivation, cell survival and tissue formation, little attention has so far been paid to optimize hydrogels for the physico-chemical demands of the biofabrication process. The resulting lack of hydrogel bioinks have been identified as one major hurdle for a more rapid progress of the field. In this review we summarize and focus on the deposition process, the parameters and demands of hydrogels in biofabrication, with special attention to robotic dispensing as an approach that generates constructs of clinically relevant dimensions. We aim to highlight this current lack of effectual hydrogels within biofabrication and initiate new ideas and developments in the design and tailoring of hydrogels. The successful development of a "printable" hydrogel that supports cell adhesion, migration, and differentiation will significantly advance this exciting and promising approach for tissue engineering.
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  44. 44
    Wu, Y.; Xiang, Y.; Fang, J.; Li, X.; Lin, Z.; Dai, G.; Yin, J.; Wei, P.; Zhang, D. The Influence of the Stiffness of GelMA Substrate on the Outgrowth of PC12 Cells. Biosci. Rep. 2019, 39 (1), BSR20181748  DOI: 10.1042/BSR20181748
    Google Scholar
    There is no corresponding record for this reference.
  45. 45
    Chalard, A. E.; Dixon, A. W.; Taberner, A. J.; Malmström, J. Visible-Light Stiffness Patterning of GelMA Hydrogels Towards In Vitro Scar Tissue Models. Front. Cell Dev. Biol. 2022, 10, 946754  DOI: 10.3389/fcell.2022.946754
    Google Scholar
    45
    Visible-Light Stiffness Patterning of GelMA Hydrogels Towards In Vitro Scar Tissue Models
    Chalard Anais E; Malmstrom Jenny; Chalard Anais E; Malmstrom Jenny; Dixon Alexander W; Taberner Andrew J; Taberner Andrew J
    Frontiers in cell and developmental biology (2022), 10 (), 946754 ISSN:2296-634X.
    Variations in mechanical properties of the extracellular matrix occurs in various processes, such as tissue fibrosis. The impact of changes in tissue stiffness on cell behaviour are studied in vitro using various types of biomaterials and methods. Stiffness patterning of hydrogel scaffolds, through the use of stiffness gradients for instance, allows the modelling and studying of cellular responses to fibrotic mechanisms. Gelatine methacryloyl (GelMA) has been used extensively in tissue engineering for its inherent biocompatibility and the ability to precisely tune its mechanical properties. Visible light is now increasingly employed for crosslinking GelMA hydrogels as it enables improved cell survival when performing cell encapsulation. We report here, the photopatterning of mechanical properties of GelMA hydrogels with visible light and eosin Y as the photoinitiator using physical photomasks and projection with a digital micromirror device. Using both methods, binary hydrogels with areas of different stiffnesses and hydrogels with stiffness gradients were fabricated. Their mechanical properties were characterised using force indentation with atomic force microscopy, which showed the efficiency of both methods to spatially pattern the elastic modulus of GelMA according to the photomask or the projected pattern. Crosslinking through projection was also used to build constructs with complex shapes. Overall, this work shows the feasibility of patterning the stiffness of GelMA scaffolds, in the range from healthy to pathological stiffness, with visible light. Consequently, this method could be used to build in vitro models of healthy and fibrotic tissue and study the cellular behaviours involved at the interface between the two.
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  46. 46
    Norioka, C.; Inamoto, Y.; Hajime, C.; Kawamura, A.; Miyata, T. A Universal Method to Easily Design Tough and Stretchable Hydrogels. NPG Asia Mater. 2021, 13 (1), 34,  DOI: 10.1038/s41427-021-00302-2
    Google Scholar
    46
    A universal method to easily design tough and stretchable hydrogels
    Norioka, Chisa; Inamoto, Yuino; Hajime, Chika; Kawamura, Akifumi; Miyata, Takashi
    NPG Asia Materials (2021), 13 (1), 34CODEN: NAMPCE; ISSN:1884-4057. (Nature Research)
    Abstr.: Hydrogels are flexible materials that have high potential for use in various applications due to their unique properties. However, their applications are greatly restricted by the low mech. performance caused by high water content and inhomogeneous networks. This paper reports a universal strategy for easily prepg. hydrogels that are tough and stretchable without any special structures or complicated processes. Our strategy involves tuning the polymn. conditions to form networks with many polymer chain entanglements to achieve energy dissipation. Tough and stretchable hydrogels can be prepd. by free radical polymn. with a high monomer concn. and low cross-linker content to optimize the balance between phys. and chem. cross-links by entanglements and covalent bonds, resp. The strategy of using polymer chain entanglements for energy dissipation allows us to overcome the limitation of low mech. performance, which leads to the wide practical use of hydrogels.
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  47. 47
    Foudazi, R.; Zowada, R.; Manas-Zloczower, I.; Feke, D. L. Porous Hydrogels: Present Challenges and Future Opportunities. Langmuir 2023, 39 (6), 2092– 2111,  DOI: 10.1021/acs.langmuir.2c02253
    Google Scholar
    47
    Porous Hydrogels: Present Challenges and Future Opportunities
    Foudazi, Reza; Zowada, Ryan; Manas-Zloczower, Ica; Feke, Donald L.
    Langmuir (2023), 39 (6), 2092-2111CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    A review. In this feature article, we critically review the phys. properties of porous hydrogels and their prodn. methods. Our main focus is nondense hydrogels that have phys. pores besides the space available between adjacent crosslinks in the polymer network. After reviewing theories on the kinetics of swelling, equil. swelling, the structure-stiffness relationship, and solute diffusion in dense hydrogels, we propose future directions to develop models for porous hydrogels. The aim is to show how porous hydrogels can be designed and produced for studies leading to the modeling of phys. properties. Addnl., different methods that are used for making hydrogels with phys. incorporated pores are briefly reviewed while discussing the potentials, challenges, and future directions for each method. Among kinetic methods, we discuss bubble generation approaches including reactions, gas injection, phase sepn., electrospinning, and freeze-drying. Templating approaches discussed are solid-phase, self-assembled amphiphiles, emulsion, and foam methods.
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  48. 48
    Meesuk, L.; Suwanprateeb, J.; Thammarakcharoen, F.; Tantrawatpan, C.; Kheolamai, P.; Palang, I.; Tantikanlayaporn, D.; Manochantr, S. Osteogenic Differentiation and Proliferation Potentials of Human Bone Marrow and Umbilical Cord-Derived Mesenchymal Stem Cells on the 3D-Printed Hydroxyapatite Scaffolds. Sci. Rep. 2022, 12 (1), 19509,  DOI: 10.1038/s41598-022-24160-2
    Google Scholar
    48
    Osteogenic differentiation and proliferation potentials of human bone marrow and umbilical cord-derived mesenchymal stem cells on the 3D-printed hydroxyapatite scaffolds
    Meesuk, Ladda; Suwanprateeb, Jintamai; Thammarakcharoen, Faungchat; Tantrawatpan, Chairat; Kheolamai, Pakpoom; Palang, Iyapa; Tantikanlayaporn, Duangrat; Manochantr, Sirikul
    Scientific Reports (2022), 12 (1), 19509CODEN: SRCEC3; ISSN:2045-2322. (Nature Portfolio)
    Mesenchymal stem cells (MSCs) are a promising candidate for bone repair. However, the maintenance of MSCs injected into the bone injury site remains inefficient. A potential approach is to develop a bone-liked platform that incorporates MSCs into a biocompatible 3D scaffold to facilitate bone grafting into the desired location. Bone tissue engineering is a multistep process that requires optimizing several variables, including the source of cells, osteogenic stimulation factors, and scaffold properties. This study aims to evaluate the proliferation and osteogenic differentiation potentials of MSCs cultured on 2 types of 3D-printed hydroxyapatite, including a 3D-printed HA and biomimetic calcium phosphate-coated 3D-printed HA. MSCs from bone marrow (BM-MSCs) and umbilical cord (UC-MSCs) were cultured on the 3D-printed HA and coated 3D-printed HA. SEM and immunofluorescence staining were used to examine the characteristics and the attachment of MSCs to the scaffolds. Addnl., the cell proliferation was monitored, and the ability of cells to differentiate into osteoblast was assessed using alk. phosphatase (ALP) activity and osteogenic gene expression. The BM-MSCs and UC-MSCs attached to a plastic culture plate with a spindle-shaped morphol. exhibited an immunophenotype consistent with the characteristics of MSCs. Both MSC types could attach and survive on the 3D-printed HA and coated 3D-printed HA scaffolds. The MSCs cultured on these scaffolds displayed sufficient osteoblastic differentiation capacity, as evidenced by increased ALP activity and the expression of osteogenic genes and proteins compared to the control. Interestingly, MSCs grown on coated 3D-printed HA exhibited a higher ALP activity and osteogenic gene expression than those cultured on the 3D-printed HA. The finding indicated that BM-MSCs and UC-MSCs cultured on the 3D-printed HA and coated 3D-printed HA scaffolds could proliferate and differentiate into osteoblasts. Thus, the HA scaffolds could provide a suitable and favorable environment for the 3D culture of MSCs in bone tissue engineering. Addnl., biomimetic coating with octacalcium phosphate may improve the biocompatibility of the bone regeneration scaffold.
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  1. Yifan Lu, Xiangxin Lou, Jia Jiang, Jiaxing Wang, Xiaochun Peng, Haochen Yao, Jinglei Wu. Antioxidative, Anti-Inflammatory, Antibacterial, Photo-Cross-Linkable Hydrogel of Gallic Acid–Chitosan Methacrylate: Synthesis, In Vitro, and In Vivo Assessments. Biomacromolecules 2024, 25 (7) , 4358-4373. https://doi.org/10.1021/acs.biomac.4c00410
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  • Abstract

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    Figure 1

    Figure 1. GelMA synthesis and cross-linking strategies: (A) 1H NMR spectra of unfunctionalized gelatin and GelMA in D2O. The peak around 2.9 ppm is associated with the lysine methylene proton on the gelatin backbone and was used to monitor the methacrylation reaction and determine the degree of functionalization; (B) schematic illustration of two strategies of GelMA cross-linking presented in the current work: (I) dual cross-linking based on physical gelation at 5 °C, followed by photoinduced cross-linking and (II) standard cross-linking based on the visible light exposure.

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    Figure 2

    Figure 2. Optimization of GelMA cross-linking parameters to match the stiffness of osteoid tissue: (A) rheological and mechanical characterization of G10 exposed to physical cross-linking only (PC) and DC incubated up to 39 h at 5 °C, PC + SC─hypothetical value of dual-cross-linking plotted as physical gelation + offset value for chemically cross-linked G10; Poisson ratio of 0.5 assumed to convert moduli through E = 3·G; (B) compressive modulus of G5-SC and G5-DC samples incubated at 5 °C for 1 h followed by chemical cross-linking up to 180 s; significant difference was observed within various cross-linking times of G5-DC with the p < 0.0001 (****) apart from 10 vs 13 s (ns) and 30 vs 60 s (ns); the p < 0.0001 (****) was also noted between G5-SC and G5-DC (each cross-linking time).

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    Figure 3

    Figure 3. Characterization approaches of G10-SC and G5-DC: (A) influence of the time of chemical cross-linking on the compressive modulus of G10-SC and G5-DC detected using DMA; #─literature-based compressive modulus of osteoid tissue; (B) swelling degree of the samples fabricated using different strategies of cross-linking and incubated in PBS up to 72 h at 37 °C; (C) metabolic activity of hBMSCs embedded into G10-SC and G5-DC determined by an Alamar Blue assay; metabolic activity is presented as a % of reduced resazurin by hBMSCs cells vs 2D control.

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    Figure 4

    Figure 4. Characterization of GelMA constructs with PEO addition/removal: (A) compressive modulus of G5- and G10-based specimens; samples without PEO addition served as a control─G5-DC and G10-SC; (B) water absorption determination of G5- and G10 samples with 20 vol % addition after 24 h of incubation in PBS at 37 °C compared to pristine G5-DC and G10-SC.

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    Figure 5

    Figure 5. Quantification of porosity changes in freeze-dried G5- and G10-based samples: (A) schematic workflow of intended PEO removal from GelMA structure during 24 h incubation; (B) micro-CT scan reconstructions at day 0 (D0, samples were fabricated according to the cross-linking approach and then freeze-dried) and day 1 (D1) of incubation in DMEM-LG medium supplemented with 10% FBS and 1% PS. The images are shown as a region of interest (ROI) of the sample with x and y equal to 2.5 mm.

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    Figure 6

    Figure 6. Biological evaluation of GelMA hydrogel constructs. (A) hBMSC cell viability over 3 weeks of incubation in osteogenic medium, (B) cell morphology visualization with actin (green) and cell nuclei (blue) staining, (C) bright-field images of G5- and G10-based samples at day 21 (D21) of incubation in osteogenic medium. Scale bar 300 μm; p = 0.0021 (**), < 0.0001 (***).

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    Figure 7

    Figure 7. ALP expression and DNA content during the in vitro culture of G5- and G10-based samples: (A) normalized alkaline phosphatase (ALP) activity to DNA content over 3 weeks of incubation in osteogenic medium, (B) single data set representing DNA levels used for ALP normalization, (C) image of shrunk G5-DC sample after immersion in cell culture medium for 24 h, which revealed the presence of escaping cells from the structure of the hydrogel; #─significant difference compared to D7-G5DC, D7-G5ME and D14-G5DC (p 0.0021); $─compared to D14-G5ME (p 0.0332); *─D7-G5DC, D7-G5ME, D14-G5DC; (p 0.0332); @─D21-G10SC, D21-G10ME (p 0.0332); &─D21-G10SC, D21-G10ME (p 0.0332); **─D21-G10SC, D21-G10ME (p 0.0332).

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  • References

    This article references 48 other publications.

    1. 1
      Salhotra, A.; Shah, H. N.; Levi, B.; Longaker, M. T. Mechanisms of Bone Development and Repair. Nat. Rev. Mol. Cell Biol. 2020, 21 (11), 696– 711,  DOI: 10.1038/s41580-020-00279-w
      1
      Mechanisms of bone development and repair
      Salhotra, Ankit; Shah, Harsh N.; Levi, Benjamin; Longaker, Michael T.
      Nature Reviews Molecular Cell Biology (2020), 21 (11), 696-711CODEN: NRMCBP; ISSN:1471-0072. (Nature Research)
      Abstr.: Bone development occurs through a series of synchronous events that result in the formation of the body scaffold. The repair potential of bone and its surrounding microenvironment - including inflammatory, endothelial and Schwann cells - persists throughout adulthood, enabling restoration of tissue to its homeostatic functional state. The isolation of a single skeletal stem cell population through cell surface markers and the development of single-cell technologies are enabling precise elucidation of cellular activity and fate during bone repair by providing key insights into the mechanisms that maintain and regenerate bone during homeostasis and repair. Increased understanding of bone development, as well as normal and aberrant bone repair, has important therapeutic implications for the treatment of bone disease and ageing-related degeneration.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhslOnsrrO&md5=07ce32de7369b65e140e0a5e8eecea0b
    2. 2
      Bolamperti, S.; Villa, I.; Rubinacci, A. Bone Remodeling: An Operational Process Ensuring Survival and Bone Mechanical Competence. Bone Res. 2022, 10 (1), 48,  DOI: 10.1038/s41413-022-00219-8
      2
      Bone remodeling: an operational process ensuring survival and bone mechanical competence
      Bolamperti, Simona; Villa, Isabella; Rubinacci, Alessandro
      Bone Research (2022), 10 (1), 48CODEN: BROEBB; ISSN:2095-6231. (Nature Portfolio)
      Abstr.: Bone remodeling replaces old and damaged bone with new bone through a sequence of cellular events occurring on the same surface without any change in bone shape. It was initially thought that the basic multicellular unit (BMU) responsible for bone remodeling consists of osteoclasts and osteoblasts functioning through a hierarchical sequence of events organized into distinct stages. However, recent discoveries have indicated that all bone cells participate in BMU formation by interacting both simultaneously and at different differentiation stages with their progenitors, other cells, and bone matrix constituents. Therefore, bone remodeling is currently considered a physiol. outcome of continuous cellular operational processes optimized to confer a survival advantage. Bone remodeling defines the primary activities that BMUs need to perform to renew successfully bone structural units. Hence, this review summarizes the current understanding of bone remodeling and future research directions with the aim of providing a clin. relevant biol. background with which to identify targets for therapeutic strategies in osteoporosis.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhvVGlsr%252FM&md5=23f3dd378dc01345736e4bbf5b59d164
    3. 3
      Marotti, G. Morphological and Quantitative Aspects of Bone Formation and Mineralization. In Bone Regulatory Factors; NATO ASI Series; Pecile, A.; de Bernard, B., Eds.; Springer US: Boston, MA, 1990; pp 39– 53.
      There is no corresponding record for this reference.
    4. 4
      Akter, F.; Ibanez, J. Chapter 8 - Bone and Cartilage Tissue Engineering. In Tissue Engineering Made Easy; Akter, F., Ed.; Academic Press, 2016; pp 77– 97.
      There is no corresponding record for this reference.
    5. 5
      Canadas, R. F.; Pina, S.; Marques, A. P.; Oliveira, J. M.; Reis, R. L. Chapter 7 - Cartilage and Bone Regeneration─How Close Are We to Bedside? In Translating Regenerative Medicine to the Clinic; Laurence, J., Ed.; Academic Press: Boston, 2016; pp 89– 106.
      There is no corresponding record for this reference.
    6. 6
      Baldwin, P.; Li, D. J.; Auston, D. A.; Mir, H. S.; Yoon, R. S.; Koval, K. J. Autograft, Allograft, and Bone Graft Substitutes: Clinical Evidence and Indications for Use in the Setting of Orthopaedic Trauma Surgery. J. Orthop. Trauma 2019, 33 (4), 203– 213,  DOI: 10.1097/BOT.0000000000001420
      6
      Autograft, Allograft, and Bone Graft Substitutes: Clinical Evidence and Indications for Use in the Setting of Orthopaedic Trauma Surgery
      Baldwin Paul; Koval Kenneth J; Li Deborah J; Auston Darryl A; Mir Hassan S; Yoon Richard S
      Journal of orthopaedic trauma (2019), 33 (4), 203-213 ISSN:.
      Bone grafts are the second most common tissue transplanted in the United States, and they are an essential treatment tool in the field of acute and reconstructive traumatic orthopaedic surgery. Available in cancellous, cortical, or bone marrow aspirate form, autogenous bone graft is regarded as the gold standard in the treatment of posttraumatic conditions such as fracture, delayed union, and nonunion. However, drawbacks including donor-site morbidity and limited quantity of graft available for harvest make autograft a less-than-ideal option for certain patient populations. Advancements in allograft and bone graft substitutes in the past decade have created viable alternatives that circumvent some of the weak points of autografts. Allograft is a favorable alternative for its convenience, abundance, and lack of procurement-related patient morbidity. Options include structural, particulate, and demineralized bone matrix form. Commonly used bone graft substitutes include calcium phosphate and calcium sulfate synthetics-these grafts provide their own benefits in structural support and availability. In addition, different growth factors including bone morphogenic proteins can augment the healing process of bony defects treated with grafts. Autograft, allograft, and bone graft substitutes all possess their own varying degrees of osteogenic, osteoconductive, and osteoinductive properties that make them better suited for different procedures. It is the purpose of this review to characterize these properties and present clinical evidence supporting their indications for use in the hopes of better elucidating treatment options for patients requiring bone grafting in an orthopaedic trauma setting.
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    7. 7
      Walejewska, E.; Idaszek, J.; Heljak, M.; Chlanda, A.; Choinska, E.; Hasirci, V.; Swieszkowski, W. The Effect of Introduction of Filament Shift on Degradation Behaviour of PLGA- and PLCL-Based Scaffolds Fabricated via Additive Manufacturing. Polym. Degrad. Stab. 2020, 171, 109030  DOI: 10.1016/j.polymdegradstab.2019.109030
      7
      The effect of introduction of filament shift on degradation behaviour of PLGA- and PLCL-based scaffolds fabricated via additive manufacturing
      Walejewska, Ewa; Idaszek, Joanna; Heljak, Marcin; Chlanda, Adrian; Choinska, Emilia; Hasirci, Vasif; Swieszkowski, Wojciech
      Polymer Degradation and Stability (2020), 171 (), 109030CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)
      The degrdn. rate of polyester scaffolds has been emphasized as one of the main areas of concern in bone tissue engineering. In ideal conditions, the degrdn. of polymeric constructs should match regeneration of the injured tissue. Thus, there is an imperative need to strictly define and understand determinants influencing the degrdn. rate of scaffolds. In this study, we focused on the effect of filament shift introduction on degrdn. behavior of the polymeric-based scaffolds. The poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide-co-ε-caprolactone) (PLCL) and their tricalcium-phosphate-loaded (TCP) composites contg. 20 and 40 wt% of filler, were utilized to fabricate constructs using modified fused deposition modeling (FDM). The scaffolds were designed with filament lay-down pattern of 0°/90° and with or without the modifications of filament distance in n+2 layer, shifted and non-shifted constructs were obtained, resp. To investigate the degrdn. profile, the change of mass, pH, water absorption and initial mol. wt. (Mw0) loss was obsd. during the degrdn. study in phosphate buffered saline (PBS) at 37°C for up to 48 wk. The scaffold morphol. was evaluated utilizing SEM (SEM) and the visualization of the topog. was performed utilizing at. force microscopy (AFM). Surface area to vol. ratio (SVR) and porosity were detd. using micro-computed tomog. (μCT). The fluid flow simulations were used to define the permeability of two investigated groups of scaffolds. The results of this study clearly demonstrate the accelerating effect of filament shift introduction on degrdn. behavior in the scaffolds with similar porosity and SVR. The decrease of Mw0 was significantly higher in case of all shifted samples. We assume that faster degrdn. of shifted constructs may be attributed to their tortuosity, making them less permeable and prone to the degrdn., as the result of the accumulation of acidic products in the tortuous architecture of the samples. Thus, the effect of introduction of filament shift into scaffold architecture comprise an attractive approach to influence the degrdn. rate in case of bone regeneration with the use of polyesters scaffolds.
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    8. 8
      Jaroszewicz, J.; Idaszek, J.; Choinska, E.; Szlazak, K.; Hyc, A.; Osiecka-Iwan, A.; Swieszkowski, W.; Moskalewski, S. Formation of Calcium Phosphate Coatings within Polycaprolactone Scaffolds by Simple, Alkaline Phosphatase Based Method. Mater. Sci. Eng., C 2019, 96, 319– 328,  DOI: 10.1016/j.msec.2018.11.027
      8
      Formation of calcium phosphate coatings within polycaprolactone scaffolds by simple, alkaline phosphatase based method
      Jaroszewicz, Jakub; Idaszek, Joanna; Choinska, Emilia; Szlazak, Karol; Hyc, Anna; Osiecka-Iwan, Anna; Swieszkowski, Wojciech; Moskalewski, Stanislaw
      Materials Science & Engineering, C: Materials for Biological Applications (2019), 96 (), 319-328CODEN: MSCEEE; ISSN:0928-4931. (Elsevier B.V.)
      The paper presents a novel approach to the prodn. of calcium phosphate coatings of scaffolds. Mineral deposits were formed during incubation of polycaprolactone (PCL) scaffolds with bovine intestinal alk. phosphatase in sodium glycerophosphate and calcium chloride medium. To modify hydrophobic surface of scaffolds and intensify attachment of coating, scaffolds were incubated at 50°C (thermal activation, TA) or at 37°C after short exposition to lipase (lipase activation, LA). Micro-computed tomog. observations demonstrated that both methods resulted in deposition of mineral on the surface of external and internal walls of the scaffolds. Ppt. formed after thermal and lipase activation contained particles with av. size of 200-400 nm, and the shape of donuts. In thermal activated PCL coatings X-ray diffraction disclosed peaks typical for hydroxyapatite (HAp), while after lipase activation these peaks could be precisely defined only if left for 6 days in the incubation medium. The Fourier-transform IR spectroscopy suggested cryst. structure of HAp both after thermal and lipase activation. The adherence of bone marrow mesenchymal stem cells was initially higher on coated than pristine PCL, but during 7 days of culture the cell no. increased and was similar on all tested samples. Alk. phosphatase activity, considered as a sign of osteogenic differentiation, measured on PCL samples after 7 days was 2-3 times lower on pristine PCL than on the coated samples, but after 2 wk increased significantly and reached similar value as on the calcium phosphate substrates.
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    9. 9
      Idaszek, J.; Bruinink, A.; Święszkowski, W. Ternary Composite Scaffolds with Tailorable Degradation Rate and Highly Improved Colonization by Human Bone Marrow Stromal Cells. J. Biomed. Mater. Res., Part A 2015, 103 (7), 2394– 2404,  DOI: 10.1002/jbm.a.35377
      9
      Ternary composite scaffolds with tailorable degradation rate and highly improved colonization by human bone marrow stromal cells
      Idaszek, J.; Bruinink, A.; Swieszkowski, W.
      Journal of Biomedical Materials Research, Part A (2015), 103 (7), 2394-2404CODEN: JBMRCH; ISSN:1549-3296. (John Wiley & Sons, Inc.)
      Poly(ε-caprolactone), PCL, is of great interest for fabrication of biodegradable scaffolds due to its high compatibility with various manufg. techniques, esp. Fused Deposition Modeling (FDM). However, slow degrdn. and low strength make application of PCL limited only to longer-term bioresorbable and non-load bearing implants. To overcome latter drawbacks, ternary PCL-based composite fibrous scaffolds consisting of 70-95 wt. % PCL, 5 wt. % Tricalcium Phosphate (TCP) and 0-25 wt. % poly(lactide-co-glycolide) (PLGA) were fabricated using FDM. In the present study, the effect of compn. of the scaffolds on their mech. properties, degrdn. kinetics, and surface properties (wettability, surface energy, and roughness) was investigated and correlated with response of human bone marrow mesenchymal stromal cells (HBMC). The presence of PLGA increased degrdn. kinetics, surface roughness and significantly improved scaffold colonization. Of the evaluated surface properties only the wettability was correlated with the surface area colonized by HBMC. This study demonstrates that introduction of PLGA into PCL-TCP binary composite could largely abolish the disadvantages of the PCL matrix and improve biocompatibility by increasing wettability and polar interactions rather than surface roughness. Addnl., we showed great potential of multicellular spheroids as a sensitive in vitro tool for detection of differences in chem. of 3D scaffolds. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103: 2394-2404, 2015.
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    10. 10
      Bartnikowski, M.; Dargaville, T. R.; Ivanovski, S.; Hutmacher, D. W. Degradation Mechanisms of Polycaprolactone in the Context of Chemistry, Geometry and Environment. Prog. Polym. Sci. 2019, 96, 1– 20,  DOI: 10.1016/j.progpolymsci.2019.05.004
      10
      Degradation mechanisms of polycaprolactone in the context of chemistry, geometry and environment
      Bartnikowski, Michal; Dargaville, Tim R.; Ivanovski, Saso; Hutmacher, Dietmar W.
      Progress in Polymer Science (2019), 96 (), 1-20CODEN: PRPSB8; ISSN:0079-6700. (Elsevier Ltd.)
      A review, we identify mechanisms of PCL degrdn. across a range of mainly biomedical applications, exploring the role of the polymer structure and form, radical interactions, temp., pH, enzymic activity, and cellular phagocytosis. We examine how polymer chem. has been used to alter PCL degrdn. rates and mechanisms, and present cases where such manipulations may affect the applications of PCL. Significantly, our anal. identifies currently undescribed trends in PCL degrdn. Namely, we observe that mol. wt. decreases at a consistent rate regardless of the initial value, and does so at a linear rate in vitro and an exponential rate in vivo. Both mech. properties and mass loss are strongly influenced by construct geometry and environmental conditions. We further assess the current biomedical literature on the degrdn. of PCL copolymers and its composites. The formation of novel PCL copolymers or composites is often used to broaden the versatility and applicability of the polymer, although this approach is rarely explored beyond initial research. Novel biomaterials overall rarely emerge from research, with inherent issues such as the reproducibility of synthesis, manufg., or characterization methods and outcomes further impeding their translation. We conclude the review with a summary of the current state of the tailorability of PCL-based polymers and composites, and offer recommendations for the future research direction of the field.
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    11. 11
      Florencio-Silva, R.; Sasso, G. R. D. S.; Sasso-Cerri, E.; Simões, M. J.; Cerri, P. S. Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells. BioMed. Res. Int. 2015, 2015, 421746  DOI: 10.1155/2015/421746
      11
      Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells
      Florencio-Silva Rinaldo; Sasso Gisela Rodrigues da Silva; Simoes Manuel Jesus; Sasso-Cerri Estela; Cerri Paulo Sergio
      BioMed research international (2015), 2015 (), 421746 ISSN:.
      Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.
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    12. 12
      Xiong, Y.; Xiong, Y. Applications of Bone Regeneration Hydrogels in the Treatment of Bone Defects: A Review. J. Mater. Sci. 2022, 57 (2), 887– 913,  DOI: 10.1007/s10853-021-06675-7
      12
      Applications of bone regeneration hydrogels in the treatment of bone defects: a review
      Xiong, Yukun; Xiong, Yuzhu
      Journal of Materials Science (2022), 57 (2), 887-913CODEN: JMTSAS; ISSN:0022-2461. (Springer)
      A review. Hydrogels can be designed as scaffolds in bone tissue engineering for more efficient healing of bone defects. Bone regeneration hydrogels have attracted extensive attention because of their good biocompatibility and excellent ability in promoting bone regeneration. This review will introduce the methods of bone regeneration hydrogels in the treatment of bone defects. Namely, promoting differentiation and proliferation of osteoblasts, promoting angiogenesis, regulating immune response and promoting mineralization. With the aim to deeply understand the development of bone regeneration hydrogels, we evaluate and summarize its characteristic, so as to help the future research.
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    13. 13
      Chen, J.; Chin, A.; Almarza, A. J.; Taboas, J. M. Hydrogel to Guide Chondrogenesis versus Osteogenesis of Mesenchymal Stem Cells for Fabrication of Cartilaginous Tissues. Biomed. Mater. Bristol Engl. 2020, 15 (4), 045006  DOI: 10.1088/1748-605X/ab401f
      13
      Hydrogel to guide chondrogenesis versus osteogenesis of mesenchymal stem cells for fabrication of cartilaginous tissues
      Chen Jingming; Chin Adam; Almarza Alejandro J; Taboas Juan M
      Biomedical materials (Bristol, England) (2020), 15 (4), 045006 ISSN:.
      The ideal combination of hydrogel components for regeneration of cartilage and cartilaginous interfaces is a significant challenge because control over differentiation into multiple lineages is necessary. Stabilization of the phenotype of stem cell derived chondrocytes is needed to avoid undesired progression to terminal hypertrophy and tissue mineralization. A novel ternary blend hydrogel composed of methacrylated poly(ethylene glycol) (PEG), gelatin, and heparin (PGH) was designed to guide chondrogenesis by bone marrow derived mesenchymal stem cells (BMSCs) and maintenance of their cartilaginous phenotype. The hydrogel material effects on chondrogenic and osteogenic differentiation by BMSCs were evaluated in comparison to methacrylated gelatin hydrogel (GEL), a conventional bioink used for both chondrogenic and osteogenic applications. PGH and GEL hydrogels were loaded with goat BMSCs and cultured in chondrogenic and osteogenic mediums in vitro over six weeks. The PGH showed no sign of mineral deposition in an osteogenic environment in vitro. To further evaluate material effects, the hydrogels were loaded with adult human BMSCs (hBMSCs) and transforming growth factor β-3 and grown in subcutaneous pockets in mice over eight weeks. Consistent with the in vitro results, the PGH had greater potential to induce chondrogenesis by BMSCs in vivo compared to the GEL as evidenced by elevated gene expression of chondrogenic markers, supporting its potential for stable cartilage engineering. The PGH also showed a greater percentage of GAG positive cells compared to the GEL. Unlike the GEL, the PGH hydrogel exhibited anti-osteogenic effects in vivo as evidenced by negative Von Kossa staining and suppressed gene expression of hypertrophic and osteogenic markers. By nature of their polymer composition alone, the PGH and GEL regulated BMSC differentiation down different osteochondral lineages. Thus, the PGH and GEL are promising hydrogels to regenerate stratified cartilaginous interfacial tissues in situ, such as the mandibular condyle surface, using undifferentiated BMSCs and a stratified scaffold design.
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    14. 14
      Wang, M.; Guo, Y.; Deng, Z.; Xu, P. Engineering Elastic Bioactive Composite Hydrogels for Promoting Osteogenic Differentiation of Embryonic Mesenchymal Stem Cells. Front. Bioeng. Biotechnol. 2022, 10, 1022153  DOI: 10.3389/fbioe.2022.1022153
      14
      Engineering elastic bioactive composite hydrogels for promoting osteogenic differentiation of embryonic mesenchymal stem cells
      Wang Min; Xu Peng; Guo Yi; Deng Zexing
      Frontiers in bioengineering and biotechnology (2022), 10 (), 1022153 ISSN:2296-4185.
      The development of bioactive materials with good mechanical properties and promotion of stem cell osteogenic differentiation has important application prospects in bone tissue engineering. In this paper, we designed a novel organic-inorganic composite hydrogel (FPIGP@BGN-Sr) utilizing diacrylated F127 (DA-PF127), β-glycerophosphate-modified polyitaconate (PIGP) and strontium-doped bioactive glass nanoparticles (BGN-Sr) through free radical polymerization and coordination interactions and then evaluated its promoting effect on the osteogenic differentiation of mouse embryonic mesenchymal stem cells in detail. The results showed that the FPIGP@BGN-Sr hydrogel exhibited a controlled storage modulus by changing the amount of BGN-Sr. Notably, the FPIGP@BGN-Sr hydrogel possessed excellent elastic ability with a compressive strain of up to 98.6% and negligible change in mechanical properties after 10 cycles of compression. In addition, the FPIGP@BGN-Sr hydrogel had good cytocompatibility, maintained the activity and proliferation of mouse embryonic mesenchymal stem cells (C3H10T1/2), and effectively enhanced the activity of alkaline phosphatase, osteogenic gene expression and biomineralization ability of the cells. In conclusion, the excellent mechanical properties and osteogenic biological activity of the FPIGP@BGN-Sr hydrogel make it a promising organic-inorganic composite bioactive material for stem cell-based bone regeneration.
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    15. 15
      Chen, Z.; Luo, Q.; Lin, C.; Kuang, D.; Song, G. Simulated Microgravity Inhibits Osteogenic Differentiation of Mesenchymal Stem Cells via Depolymerizing F-Actin to Impede TAZ Nuclear Translocation. Sci. Rep. 2016, 6 (1), 30322,  DOI: 10.1038/srep30322
      15
      Simulated microgravity inhibits osteogenic differentiation of mesenchymal stem cells via depolymerizing F-actin to impede TAZ nuclear translocation
      Chen, Zhe; Luo, Qing; Lin, Chuanchuan; Kuang, Dongdong; Song, Guanbin
      Scientific Reports (2016), 6 (), 30322CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
      Microgravity induces obsd. bone loss in space flight, and reduced osteogenesis of bone mesenchymal stem cells (BMSCs) partly contributes to this phenomenon. Abnormal regulation or functioning of the actin cytoskeleton induced by microgravity may cause the inhibited osteogenesis of BMSCs, but the underlying mechanism remains obscure. In this study, we demonstrated that actin cytoskeletal changes regulate nuclear aggregation of the transcriptional coactivator with PDZ-binding motif (TAZ), which is indispensable for osteogenesis of bone mesenchymal stem cells (BMSCs). Moreover, we utilized a clinostat to model simulated microgravity (SMG) and demonstrated that SMG obviously depolymd. F-actin and hindered TAZ nuclear translocation. Interestingly, stabilizing the actin cytoskeleton induced by Jasplakinolide (Jasp) significantly rescued TAZ nuclear translocation and recovered the osteogenic differentiation of BMSCs in SMG, independently of large tumor suppressor 1(LATS1, an upstream kinase of TAZ). Furthermore, lysophosphatidic acid (LPA) also significantly recovered the osteogenic differentiation of BMSCs in SMG through the F-actin-TAZ pathway. Taken together, we propose that the depolymd. actin cytoskeleton inhibits osteogenic differentiation of BMSCs through impeding nuclear aggregation of TAZ, which provides a novel connection between F-actin cytoskeleton and osteogenesis of BMSCs and has important implications in bone loss caused by microgravity.
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    16. 16
      Luo, T.; Tan, B.; Zhu, L.; Wang, Y.; Liao, J. A Review on the Design of Hydrogels With Different Stiffness and Their Effects on Tissue Repair. Front. Bioeng. Biotechnol. 2022, 10, 817391  DOI: 10.3389/fbioe.2022.817391
      16
      A Review on the Design of Hydrogels With Different Stiffness and Their Effects on Tissue Repair
      Luo Tianyi; Tan Bowen; Zhu Lengjing; Wang Yating; Liao Jinfeng; Luo Tianyi; Zhu Lengjing; Wang Yating
      Frontiers in bioengineering and biotechnology (2022), 10 (), 817391 ISSN:2296-4185.
      Tissue repair after trauma and infection has always been a difficult problem in regenerative medicine. Hydrogels have become one of the most important scaffolds for tissue engineering due to their biocompatibility, biodegradability and water solubility. Especially, the stiffness of hydrogels is a key factor, which influence the morphology of mesenchymal stem cells (MSCs) and their differentiation. The researches on this point are meaningful to the field of tissue engineering. Herein, this review focus on the design of hydrogels with different stiffness and their effects on the behavior of MSCs. In addition, the effect of hydrogel stiffness on the phenotype of macrophages is introduced, and then the relationship between the phenotype changes of macrophages on inflammatory response and tissue repair is discussed. Finally, the future application of hydrogels with a certain stiffness in regenerative medicine and tissue engineering has been prospected.
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    17. 17
      Discher, D. E.; Janmey, P.; Wang, Y. Tissue Cells Feel and Respond to the Stiffness of Their Substrate. Science 2005, 310 (5751), 1139– 1143,  DOI: 10.1126/science.1116995
      17
      Tissue Cells Feel and Respond to the Stiffness of Their Substrate
      Discher, Dennis E.; Janmey, Paul; Wang, Yu-li
      Science (Washington, DC, United States) (2005), 310 (5751), 1139-1143CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
      A review. Normal tissue cells are generally not viable when suspended in a fluid and are therefore said to be anchorage-dependent. Such cells must adhere to a solid, but a solid can be as rigid as glass or softer than a baby's skin. The behavior of some cells on soft materials is characteristic of important phenotypes; for example, cell growth on soft agar gels is used to identify cancer cells. However, an understanding of how tissue cells-including fibroblasts, myocytes, neurons, and other cell types-sense matrix stiffness is just emerging with quant. studies of cells adhering to gels (or to other cells) with which elasticity can be tuned to approx. that of tissues. Key roles in mol. pathways are played by adhesion complexes and the actin-myosin cytoskeleton, whose contractile forces are transmitted through transcellular structures. The feedback of local matrix stiffness on cell state likely has important implications for development, differentiation, disease, and regeneration.
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    18. 18
      Koons, G. L.; Diba, M.; Mikos, A. G. Materials Design for Bone-Tissue Engineering. Nat. Rev. Mater. 2020, 5 (8), 584– 603,  DOI: 10.1038/s41578-020-0204-2
      18
      Materials design for bone-tissue engineering
      Koons, Gerry L.; Diba, Mani; Mikos, Antonios G.
      Nature Reviews Materials (2020), 5 (8), 584-603CODEN: NRMADL; ISSN:2058-8437. (Nature Research)
      Abstr.: Successful materials design for bone-tissue engineering requires an understanding of the compn. and structure of native bone tissue, as well as appropriate selection of biomimetic natural or tunable synthetic materials (biomaterials), such as polymers, bioceramics, metals and composites. Scalable fabrication technologies that enable control over construct architecture at multiple length scales, including three-dimensional printing and elec.-field-assisted techniques, can then be employed to process these biomaterials into suitable forms for bone-tissue engineering. In this Review, we provide an overview of materials-design considerations for bone-tissue-engineering applications in both disease modeling and treatment of injuries and disease in humans. We outline the materials-design pathway from implementation strategy through selection of materials and fabrication methods to evaluation. Finally, we discuss unmet needs and current challenges in the development of ideal materials for bone-tissue regeneration and highlight emerging strategies in the field.
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    19. 19
      Annabi, N.; Nichol, J. W.; Zhong, X.; Ji, C.; Koshy, S.; Khademhosseini, A.; Dehghani, F. Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering. Tissue Eng. Part B Rev. 2010, 16 (4), 371– 383,  DOI: 10.1089/ten.teb.2009.0639
      19
      Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering
      Annabi, Nasim; Nichol, Jason W.; Zhong, Xia; Ji, Chengdong; Koshy, Sandeep; Khademhosseini, Ali; Dehghani, Fariba
      Tissue Engineering, Part B: Reviews (2010), 16 (4), 371-383CODEN: TEPBAB; ISSN:1937-3368. (Mary Ann Liebert, Inc.)
      A review. Tissue engineering holds great promise for regeneration and repair of diseased tissues, making the development of tissue engineering scaffolds a topic of great interest in biomedical research. Because of their biocompatibility and similarities to native extracellular matrix, hydrogels have emerged as leading candidates for engineered tissue scaffolds. However, precise control of hydrogel properties, such as porosity, remains a challenge. Traditional techniques for creating bulk porosity in polymers have demonstrated success in hydrogels for tissue engineering; however, often the conditions are incompatible with direct cell encapsulation. Emerging technologies have demonstrated the ability to control porosity and the microarchitectural features in hydrogels, creating engineered tissues with structure and function similar to native tissues. In this review, we explore the various technologies for controlling the porosity and microarchitecture within hydrogels, and demonstrate successful applications of combining these techniques.
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    20. 20
      Martinez-Garcia, F. D.; Fischer, T.; Hayn, A.; Mierke, C. T.; Burgess, J. K.; Harmsen, M. C. A Beginner’s Guide to the Characterization of Hydrogel Microarchitecture for Cellular Applications. Gels 2022, 8 (9), 535,  DOI: 10.3390/gels8090535
      20
      A Beginner's Guide to the Characterization of Hydrogel Microarchitecture for Cellular Applications
      Martinez-Garcia, Francisco Drusso; Fischer, Tony; Hayn, Alexander; Mierke, Claudia Tanja; Burgess, Janette Kay; Harmsen, Martin Conrad
      Gels (2022), 8 (9), 535CODEN: GELSAZ; ISSN:2310-2861. (MDPI AG)
      A review. The extracellular matrix (ECM) is a three-dimensional, acellular scaffold of living tissues. Incorporating the ECM into cell culture models is a goal of cell biol. studies and requires biocompatible materials that can mimic the ECM. Among such materials are hydrogels: polymeric networks that derive most of their mass from water. With the tuning of their properties, these polymer networks can resemble living tissues. The microarchitectural properties of hydrogels, such as porosity, pore size, fiber length, and surface topol. can det. cell plasticity. The adequate characterization of these parameters requires reliable and reproducible methods. However, most methods were historically standardized using other biol. specimens, such as 2D cell cultures, biopsies, or even animal models. Therefore, their translation comes with tech. limitations when applied to hydrogel-based cell culture systems. In our current work, we have reviewed the most common techniques employed in the characterization of hydrogel microarchitectures. Our review provides a concise description of the underlying principles of each method and summarizes the collective data obtained from cell-free and cell-loaded hydrogels. The advantages and limitations of each technique are discussed, and comparisons are made. The information presented in our current work will be of interest to researchers who employ hydrogels as platforms for cell culture, 3D bioprinting, and other fields within hydrogel-based research.
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    21. 21
      Klotz, B. J.; Gawlitta, D.; Rosenberg, A. J. W. P.; Malda, J.; Melchels, F. P. W. Gelatin-Methacryloyl Hydrogels: Towards Biofabrication-Based Tissue Repair. Trends Biotechnol. 2016, 34 (5), 394– 407,  DOI: 10.1016/j.tibtech.2016.01.002
      21
      Gelatin-Methacryloyl Hydrogels: Towards Biofabrication-Based Tissue Repair
      Klotz, Barbara J.; Gawlitta, Debby; Rosenberg, Antoine J. W. P.; Malda, Jos; Melchels, Ferry P. W.
      Trends in Biotechnology (2016), 34 (5), 394-407CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)
      Research over the past decade on the cell-biomaterial interface has shifted to the third dimension. Besides mimicking the native extracellular environment by 3D cell culture, hydrogels offer the possibility to generate well-defined 3D biofabricated tissue analogs. In this context, gelatin-methacryloyl (gelMA) hydrogels have recently gained increased attention. This interest is sparked by the combination of the inherent bioactivity of gelatin and the physicochem. tailorability of photo-crosslinkable hydrogels. GelMA is a versatile matrix that can be used to engineer tissue analogs ranging from vasculature to cartilage and bone. Convergence of biol. and biofabrication approaches is necessary to progress from merely proving cell functionality or construct shape fidelity towards regenerating tissues. GelMA has a crit. pioneering role in this process and could be used to accelerate the development of clin. relevant applications.
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    22. 22
      Lim, K. S.; Klotz, B. J.; Lindberg, G. C. J.; Melchels, F. P. W.; Hooper, G. J.; Malda, J.; Gawlitta, D.; Woodfield, T. B. F. Visible Light Cross-Linking of Gelatin Hydrogels Offers an Enhanced Cell Microenvironment with Improved Light Penetration Depth. Macromol. Biosci. 2019, 19 (6), e1900098  DOI: 10.1002/mabi.201900098
      There is no corresponding record for this reference.
    23. 23
      Van Den Bulcke, A. I.; Bogdanov, B.; De Rooze, N.; Schacht, E. H.; Cornelissen, M.; Berghmans, H. Structural and Rheological Properties of Methacrylamide Modified Gelatin Hydrogels. Biomacromolecules 2000, 1 (1), 31– 38,  DOI: 10.1021/bm990017d
      23
      Structural and Rheological Properties of Methacrylamide Modified Gelatin Hydrogels
      Van Den Bulcke, An I.; Bogdanov, Bogdan; De Rooze, Nadine; Schacht, Etienne H.; Cornelissen, Maria; Berghmans, Hugo
      Biomacromolecules (2000), 1 (1), 31-38CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)
      Dynamic shear oscillation measurements at small strain were used to characterize the viscoelastic properties and related differences in the mol. structure of hydrogels based on gelatin methacrylamide. Gelatin was derivatized with methacrylamide side groups and was subsequently cross-linked by radical polymn. via photoinitiation. The light treatment of methacrylamide gelatin solns. resulted in the prodn. of hydrogel films with high storage modulus (G'). Mech. spectra and thermal scanning rheol. of the obtained hydrogels are described. The temp. scan of the network below and above m.p. of gelatin allowed us to identify the resp. contributions of chem. and phys. cross-linkage to the hydrogel elastic modulus. The results indicate that the rheol. properties of the gelatin-based hydrogels can be controlled by the degree of substitution, polymer concn., initiator concn., and UV irradn. conditions.
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    24. 24
      He, J.; Sun, Y.; Gao, Q.; He, C.; Yao, K.; Wang, T.; Xie, M.; Yu, K.; Nie, J.; Chen, Y.; He, Y. Gelatin Methacryloyl Hydrogel, from Standardization, Performance, to Biomedical Application. Adv. Healthc. Mater. 2023, 12 (23), 2300395  DOI: 10.1002/adhm.202300395
      24
      Gelatin Methacryloyl Hydrogel, from Standardization, Performance, to Biomedical Application
      He, Jing; Sun, Yuan; Gao, Qing; He, Chanfan; Yao, Ke; Wang, Tongyao; Xie, Mingjun; Yu, Kang; Nie, Jing; Chen, Yuewei; He, Yong
      Advanced Healthcare Materials (2023), 12 (23), 2300395CODEN: AHMDBJ; ISSN:2192-2640. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Gelatin methacryloyl (GelMA), a photocurable hydrogel, is widely used in 3D culture, particularly in 3D bioprinting, due to its high biocompatibility, tunable physicochem. properties, and excellent formability. However, as the properties and performances of GelMA vary under different synthetic conditions, there is a lack of standardization, leading to conflicting results. In this study, a uniform std. is established to understand and enhance GelMA applications. First, the basic concept of GelMA and the d. of the mol. network (DMN) are defined. Second, two properties, degrees of substitution and ratio of solid content, as the main measurable parameters detg. the DMN are used. Third, the mechanisms and relationships between DMN and its performance in various applications in terms of porosity, viscosity, formability, mech. strength, swelling, biodegrdn., and cytocompatibility are theor. explained. The main questions that are answered: what does performance mean, why is it important, how to optimize the basic parameters to improve the performance, and how to characterize it reasonably and accurately. Finally, it is hoped that this knowledge will eliminate the need for researchers to conduct tedious and repetitive pre-expts., enable easy communication for achievements between groups under the same std., and fully explore the potential of the GelMA hydrogel.
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    25. 25
      Yue, K.; Trujillo-de Santiago, G.; Alvarez, M. M.; Tamayol, A.; Annabi, N.; Khademhosseini, A. Synthesis, Properties, and Biomedical Applications of Gelatin Methacryloyl (GelMA) Hydrogels. Biomaterials 2015, 73, 254– 271,  DOI: 10.1016/j.biomaterials.2015.08.045
      25
      Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels
      Yue, Kan; Trujillo-de Santiago, Grissel; Alvarez, Mario Moises; Tamayol, Ali; Annabi, Nasim; Khademhosseini, Ali
      Biomaterials (2015), 73 (), 254-271CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
      A review. Gelatin methacryloyl (GelMA) hydrogels have been widely used for various biomedical applications due to their suitable biol. properties and tunable phys. characteristics. GelMA hydrogels closely resemble some essential properties of native extracellular matrix (ECM) due to the presence of cell-attaching and matrix metalloproteinase responsive peptide motifs, which allow cells to proliferate and spread in GelMA-based scaffolds. GelMA is also versatile from a processing perspective. It crosslinks when exposed to light irradn. to form hydrogels with tunable mech. properties. It can also be microfabricated using different methodologies including micromolding, photomasking, bioprinting, self-assembly, and microfluidic techniques to generate constructs with controlled architectures. Hybrid hydrogel systems can also be formed by mixing GelMA with nanoparticles such as carbon nanotubes and graphene oxide, and other polymers to form networks with desired combined properties and characteristics for specific biol. applications. Recent research has demonstrated the proficiency of GelMA-based hydrogels in a wide range of tissue engineering applications including engineering of bone, cartilage, cardiac, and vascular tissues, among others. Other applications of GelMA hydrogels, besides tissue engineering, include fundamental cell research, cell signaling, drug and gene delivery, and bio-sensing.
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    26. 26
      Young, A. T.; White, O. C.; Daniele, M. A. Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels. Macromol. Biosci. 2020, 20 (12), e2000183  DOI: 10.1002/mabi.202000183
      26
      Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels
      Young, Ashlyn T.; White, Olivia C.; Daniele, Michael A.
      Macromolecular Bioscience (2020), 20 (12), 2000183CODEN: MBAIBU; ISSN:1616-5187. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Synthetically modified proteins, such as gelatin methacryloyl (GelMA), are growing in popularity for bioprinting and biofabrication. GelMA is a photocurable macromer that can rapidly form hydrogels, while also presenting bioactive peptide sequences for cellular adhesion and proliferation. The mech. properties of GelMA are highly tunable by modifying the degree of substitution via synthesis conditions, though the effects of source material and thermal gelation have not been comprehensively characterized for lower concn. gels. Herein, the effects of animal source and processing sequence are investigated on scaffold mech. properties. Hydrogels of 4-6 wt% are characterized. Depending on the temp. at crosslinking, the storage moduli for GelMA derived from pigs, cows, and cold-water fish range from 723 to 7340 Pa, 516 to 3484 Pa, and 294 to 464 Pa, resp. The max. storage moduli are achieved only by coordinated phys. gelation and chem. crosslinking. In this method, the classic thermo-reversible gelation of gelatin occurs when GelMA is cooled below a thermal transition temp., which is subsequently 'locked in' by chem. crosslinking via photocuring. The effects of coordinated phys. gelation and chem. crosslinking are demonstrated by precise photopatterning of cell-laden microstructures, inducing different cellular behavior depending on the selected mech. properties of GelMA.
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    27. 27
      Chansoria, P.; Asif, S.; Polkoff, K.; Chung, J.; Piedrahita, J. A.; Shirwaiker, R. A. Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GelMA) Hydrogels. ACS Biomater. Sci. Eng. 2021, 7 (11), 5175– 5188,  DOI: 10.1021/acsbiomaterials.1c00635
      27
      Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GelMA) Hydrogels
      Chansoria, Parth; Asif, Suleman; Polkoff, Kathryn; Chung, Jaewook; Piedrahita, Jorge A.; Shirwaiker, Rohan A.
      ACS Biomaterials Science & Engineering (2021), 7 (11), 5175-5188CODEN: ABSEBA; ISSN:2373-9878. (American Chemical Society)
      Gelatin methacryloyl (GelMA) hydrogels have emerged as promising and versatile biomaterial matrixes with applications spanning drug delivery, disease modeling, and tissue engineering and regenerative medicine. GelMA exhibits reversible thermal crosslinking at temps. below 37°C due to the entanglement of constitutive polymeric chains, and subsequent UV photo-crosslinking can covalently bind neighboring chains to create irreversibly cross-linked hydrogels. However, how these crosslinking modalities interact and can be modulated during biofabrication to control the structural and functional characteristics of this versatile biomaterial is not well explored yet. Accordingly, this work characterizes the effects of synergistic thermal and photo-crosslinking as a function of GelMA soln. temp. and UV photo-crosslinking duration during biofabrication on the hydrogels' stiffness, microstructure, proteolytic degrdn., and responses of NIH 3T3 and human adipose-derived stem cells (hASC). Smaller pore size, lower degrdn. rate, and increased stiffness are reported in hydrogels processed at lower temp. or prolonged UV exposure. In hydrogels with low stiffness, the cells were found to shear the matrix and cluster into microspheroids, while poor cell attachment was noted in high stiffness hydrogels. In hydrogels with moderate stiffness, ones processed at lower temp. demonstrated better shape fidelity and cell proliferation over time. Anal. of gene expression of hASC encapsulated within the hydrogels showed that, while the GelMA matrix assisted in maintenance of stem cell phenotype (CD44), a higher matrix stiffness resulted in higher pro-inflammatory marker (ICAM1) and markers for cell-matrix interaction (ITGA1 and ITGA10). Anal. of constructs with ultrasonically patterned hASC showed that hydrogels processed at higher temp. possessed lower structural fidelity but resulted in more cell elongation and greater anisotropy over time. These findings demonstrate the significant impact of GelMA material formulation and processing conditions on the structural and functional properties of the hydrogels. The understanding of these material-process-structure-function interactions is crit. toward optimizing the functional properties of GelMA hydrogels for different targeted applications.
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    28. 28
      Ying, G.-L.; Jiang, N.; Maharjan, S.; Yin, Y.-X.; Chai, R.-R.; Cao, X.; Yang, J.-Z.; Miri, A. K.; Hassan, S.; Zhang, Y. S. Aqueous Two-Phase Emulsion Bioink-Enabled 3D Bioprinting of Porous Hydrogels. Adv. Mater. Deerfield Beach Fla 2018, 30 (50), e1805460  DOI: 10.1002/adma.201805460
      There is no corresponding record for this reference.
    29. 29
      Khattak, S. F.; Bhatia, S. R.; Roberts, S. C. Pluronic F127 as a Cell Encapsulation Material: Utilization of Membrane-Stabilizing Agents. Tissue Eng. 2005, 11 (5–6), 974– 983,  DOI: 10.1089/ten.2005.11.974
      29
      Pluronic F127 as a Cell Encapsulation Material: Utilization of Membrane-Stabilizing Agents
      Khattak, Sarwat F.; Bhatia, Surita R.; Roberts, Susan C.
      Tissue Engineering (2005), 11 (5/6), 974-983CODEN: TIENFP; ISSN:1076-3279. (Mary Ann Liebert, Inc.)
      Thermoreversible gelation of the copolymer Pluronic F127 (generic name, poloxamer 407) in water makes it a unique candidate for cell encapsulation applications, either alone or to promote cell seeding and attachment in tissue scaffolds. At concns. of 15-20% (wt./wt.), aq. Pluronic F127 (F127) solns. gel at physiol. temps. The effect of F127 on viability and proliferation of human liver carcinoma cells (HepG2) was detd. for both liq. and gel formulations. Cell concn. and viability over a 5-day period were measured by the trypan blue assay via hemocytometry and results were confirmed in both the MTT and LDH assays. With 0.1-5% (wt./wt.) F127 (liq.), cells proliferated and maintained high viability over 5 days. However, at 10% (wt./wt.) F127 (liq.), there was a significant decrease in cell viability and no cell proliferation was evident. HepG2 cell encapsulation in F127 concns. ranging from 15 to 20% (wt./wt.) (gel) resulted in complete cell death by 5 days. This was also true for the HMEC-1 (endothelial) and L6 (muscle) cell lines evaluated. Cell-seeding d. did not affect cell survival or proliferation. Membrane-stabilizing agents (hydrocortisone, glucose, and glycerol) were added to the F127 gel formulations to improve cell viability. The steroid hydrocortisone demonstrated the most significant improvement in viability, from <2% (in F127 alone) to >70% (with 60 nM hydrocortisone added). These results suggest that F127 formulations supplemented with membrane-stabilizing agents can serve as viable cell encapsulation materials. In addn., hydrocortisone may be generally useful in the promotion of cell viability for a wide range of encapsulation materials.
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    30. 30
      Gioffredi, E.; Boffito, M.; Calzone, S.; Giannitelli, S. M.; Rainer, A.; Trombetta, M.; Mozetic, P.; Chiono, V. Pluronic F127 Hydrogel Characterization and Biofabrication in Cellularized Constructs for Tissue Engineering Applications. Procedia CIRP 2016, 49, 125– 132,  DOI: 10.1016/j.procir.2015.11.001
      There is no corresponding record for this reference.
    31. 31
      García-Couce, J.; Tomás, M.; Fuentes, G.; Que, I.; Almirall, A.; Cruz, L. J. Chitosan/Pluronic F127 Thermosensitive Hydrogel as an Injectable Dexamethasone Delivery Carrier. Gels Basel Switz. 2022, 8 (1), 44,  DOI: 10.3390/gels8010044
      There is no corresponding record for this reference.
    32. 32
      Gong, J.; Schuurmans, C. C. L.; van Genderen, A. M.; Cao, X.; Li, W.; Cheng, F.; He, J. J.; López, A.; Huerta, V.; Manríquez, J.; Li, R.; Li, H.; Delavaux, C.; Sebastian, S.; Capendale, P. E.; Wang, H.; Xie, J.; Yu, M.; Masereeuw, R.; Vermonden, T.; Zhang, Y. S. Complexation-Induced Resolution Enhancement of 3D-Printed Hydrogel Constructs. Nat. Commun. 2020, 11 (1), 1267  DOI: 10.1038/s41467-020-14997-4
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      Complexation-induced resolution enhancement of 3D-printed hydrogel constructs
      Gong, Jiaxing; Schuurmans, Carl C. L.; van Genderen, Anne Metje; Cao, Xia; Li, Wanlu; Cheng, Feng; He, Jacqueline Jialu; Lopez, Arturo; Huerta, Valentin; Manriquez, Jennifer; Li, Ruiquan; Li, Hongbin; Delavaux, Clement; Sebastian, Shikha; Capendale, Pamela E.; Wang, Huiming; Xie, Jingwei; Yu, Mengfei; Masereeuw, Rosalinde; Vermonden, Tina; Zhang, Yu Shrike
      Nature Communications (2020), 11 (1), 1267CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)
      Three-dimensional (3D) hydrogel printing enables prodn. of volumetric architectures contg. desired structures using programmed automation processes. Our study reports a unique method of resoln. enhancement purely relying on post-printing treatment of hydrogel constructs. By immersing a 3D-printed patterned hydrogel consisting of a hydrophilic polyionic polymer network in a soln. of polyions of the opposite net charge, shrinking can rapidly occur resulting in various degrees of reduced dimensions comparing to the original pattern. This phenomenon, caused by complex coacervation and water expulsion, enables us to reduce linear dimensions of printed constructs while maintaining cytocompatible conditions in a cell type-dependent manner. We anticipate our shrinking printing technol. to find widespread applications in promoting the current 3D printing capacities for generating higher-resoln. hydrogel-based structures without necessarily having to involve complex hardware upgrades or other printing parameter alterations.
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    33. 33
      Ying, G.; Jiang, N.; Parra-Cantu, C.; Tang, G.; Zhang, J.; Wang, H.; Chen, S.; Huang, N.-P.; Xie, J.; Zhang, Y. S. Bioprinted Injectable Hierarchically Porous Gelatin Methacryloyl Hydrogel Constructs with Shape-Memory Properties. Adv. Funct. Mater. 2020, 30 (46), 2003740  DOI: 10.1002/adfm.202003740
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      Bioprinted Injectable Hierarchically Porous Gelatin Methacryloyl Hydrogel Constructs with Shape-Memory Properties
      Ying, Guoliang; Jiang, Nan; Parra-Cantu, Carolina; Tang, Guosheng; Zhang, Jingyi; Wang, Hongjun; Chen, Shixuan; Huang, Ning-Ping; Xie, Jingwei; Zhang, Yu Shrike
      Advanced Functional Materials (2020), 30 (46), 2003740CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Direct injection of cell-laden hydrogels shows high potential for tissue regeneration in translational therapy. The traditional cell-laden hydrogels are often used as bulk space fillers to tissue defects after injection, likely limiting their structural controllability. On the other hand, patterned cell-laden hydrogel constructs often necessitate invasive surgical procedures. To overcome these problems, herein, a unique strategy is reported for encapsulating living human cells in a pore-forming gelatin methacryloyl (GelMA)-based bioink to ultimately produce injectable hierarchically macro-micro-nanoporous cell-laden GelMA hydrogel constructs through 3D extrusion bioprinting. The hydrogel constructs can be fabricated into various shapes and sizes that are defect-specific. Due to the hierarchically macro-micro-nanoporous structures, the cell-laden hydrogel constructs can readily recover to their original shapes, and sustain high cell viability, proliferation, spreading, and differentiation after compression and injection. In addn., in vivo studies further reveal that the hydrogel constructs can integrate well with the surrounding host tissues. These findings suggest that the unique 3D-bioprinted pore-forming GelMA hydrogel constructs are promising candidates for applications in minimally invasive tissue regeneration and cell therapy.
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    34. 34
      Ying, G.; Manríquez, J.; Wu, D.; Zhang, J.; Jiang, N.; Maharjan, S.; Hernández Medina, D. H.; Zhang, Y. S. An Open-Source Handheld Extruder Loaded with Pore-Forming Bioink for in Situ Wound Dressing. Mater. Today Bio 2020, 8, 100074  DOI: 10.1016/j.mtbio.2020.100074
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      An open-source handheld extruder loaded with pore-forming bioink for in situ wound dressing
      Ying G; Manriquez J; Wu D; Zhang J; Maharjan S; Hernandez Medina D H; Zhang Y S; Jiang N
      Materials today. Bio (2020), 8 (), 100074 ISSN:.
      The increasing demand in rapid wound dressing and healing has promoted the development of intraoperative strategies, such as intraoperative bioprinting, which allows deposition of bioinks directly at the injury sites to conform to their specific shapes and structures. Although successes have been achieved to varying degrees, either the instrumentation remains complex and high-cost or the bioink is insufficient for desired cellular activities. Here, we report the development of a cost-effective, open-source handheld bioprinter featuring an ergonomic design, which was entirely portable powered by a battery pack. We further integrated an aqueous two-phase emulsion bioink based on gelatin methacryloyl with the handheld system, enabling convenient shape-controlled in situ bioprinting. The unique pore-forming property of the emulsion bioink facilitated liquid and oxygen transport as well as cellular proliferation and spreading, with an additional ability of good elasticity to withstand repeated mechanical compressions. These advantages of our pore-forming bioink-loaded handheld bioprinter are believed to pave a new avenue for effective wound dressing potentially in a personalized manner down the future.
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    35. 35
      Loessner, D.; Meinert, C.; Kaemmerer, E.; Martine, L. C.; Yue, K.; Levett, P. A.; Klein, T. J.; Melchels, F. P. W.; Khademhosseini, A.; Hutmacher, D. W. Functionalization, Preparation and Use of Cell-Laden Gelatin Methacryloyl–Based Hydrogels as Modular Tissue Culture Platforms. Nat. Protoc. 2016, 11 (4), 727– 746,  DOI: 10.1038/nprot.2016.037
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      Functionalization, preparation and use of cell-laden gelatin methacryloyl-based hydrogels as modular tissue culture platforms
      Loessner, Daniela; Meinert, Christoph; Kaemmerer, Elke; Martine, Laure C.; Yue, Kan; Levett, Peter A.; Klein, Travis J.; Melchels, Ferry P. W.; Khademhosseini, Ali; Hutmacher, Dietmar W.
      Nature Protocols (2016), 11 (4), 727-746CODEN: NPARDW; ISSN:1750-2799. (Nature Publishing Group)
      Progress in advancing a system-level understanding of the complexity of human tissue development and regeneration is hampered by a lack of biol. model systems that recapitulate key aspects of these processes in a physiol. context. Hence, growing demand by cell biologists for organ-specific extracellular mimics has led to the development of a plethora of 3D cell culture assays based on natural and synthetic matrixes. We developed a physiol. microenvironment of semisynthetic origin, called gelatin methacryloyl (GelMA)-based hydrogels, which combine the biocompatibility of natural matrixes with the reproducibility, stability and modularity of synthetic biomaterials. We describe here a step-by-step protocol for the prepn. of the GelMA polymer, which takes 1-2 wk to complete, and which can be used to prep. hydrogel-based 3D cell culture models for cancer and stem cell research, as well as for tissue engineering applications. We also describe quality control and validation procedures, including how to assess the degree of GelMA functionalization and mech. properties, to ensure reproducibility in exptl. and animal studies.
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    36. 36
      Celikkin, N.; Mastrogiacomo, S.; Jaroszewicz, J.; Walboomers, X. F.; Swieszkowski, W. Gelatin Methacrylate Scaffold for Bone Tissue Engineering: The Influence of Polymer Concentration. J. Biomed. Mater. Res., Part A 2018, 106 (1), 201– 209,  DOI: 10.1002/jbm.a.36226
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      Gelatin methacrylate scaffold for bone tissue engineering: The influence of polymer concentration
      Celikkin, Nehar; Mastrogiacomo, Simone; Jaroszewicz, Jakub; Walboomers, X. Frank; Swieszkowski, Wojciech
      Journal of Biomedical Materials Research, Part A (2018), 106 (1), 201-209CODEN: JBMRCH; ISSN:1549-3296. (John Wiley & Sons, Inc.)
      Gelatin methacrylate (GelMA) is an inexpensive, photocrosslinkable, cell-responsive hydrogel which has drawn attention for a wide range of tissue engineering applications. The potential of GelMA scaffolds was demonstrated to be tunable for different tissue engineering (TE) applications through modifying the polymer concn., methacrylation degree, or UV light intensity. Despite the promising results of GelMA hydrogels in tissue engineering, the influence of polymer concn. for bone tissue engineering (BTE) scaffolds was not established yet. Thus, in this study, we have demonstrated the effect of polymer concn. in GelMA scaffolds on osteogenic differentiation. We prepd. GelMA scaffolds with 5 and 10% polymer concns. and characterized the scaffolds in terms of porosity, pore size, swelling characteristics, and mech. properties. Subsequent to the scaffolds characterization, the scaffolds were seeded with bone marrow derived rat mesenchymal stem cells and cultured in osteogenic media to evaluate the possible osteogenic differentiation effect exerted by the polymer concn. After 7, 14, 21, and 28 days, DNA content, calcium deposition, and alk. phosphatase (ALP) activity of scaffolds were evaluated quant. by colorimetric bioassays. Furthermore, the distribution of the calcium deposition within the scaffolds was attained qual. and quant. by microcomputer tomog. (μCT). Our data suggest that GelMA hydrogels prepd. with 5% polymer concn. has promoted homogeneous extracellular matrix calcification and it is a great candidate for BTE applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017.
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    37. 37
      Cao, X.; Ashfaq, R.; Cheng, F.; Maharjan, S.; Li, J.; Ying, G.; Hassan, S.; Xiao, H.; Yue, K.; Zhang, Y. S. A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair. Adv. Funct. Mater. 2023, 33 (33), 2307408  DOI: 10.1002/adfm.202307408
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      A Tumor-on-a-Chip System with Bioprinted Blood and Lymphatic Vessel Pair
      Cao, Xia; Ashfaq, Ramla; Cheng, Feng; Maharjan, Sushila; Li, Jun; Ying, Guoliang; Hassan, Shabir; Xiao, Haiyan; Yue, Kan; Zhang, Yu Shrike
      Advanced Functional Materials (2023), 33 (33), 2307408CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      There is no expanded citation for this reference.
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    38. 38
      Byambaa, B.; Annabi, N.; Yue, K.; Trujillo-de Santiago, G.; Alvarez, M. M.; Jia, W.; Kazemzadeh-Narbat, M.; Shin, S. R.; Tamayol, A.; Khademhosseini, A. Bioprinted Osteogenic and Vasculogenic Patterns for Engineering 3D Bone Tissue. Adv. Healthc. Mater. 2017, 6 (16), 1700015  DOI: 10.1002/adhm.201700015
      There is no corresponding record for this reference.
    39. 39
      Claaßen, C.; Claaßen, M. H.; Truffault, V.; Sewald, L.; Tovar, G. E. M.; Borchers, K.; Southan, A. Quantification of Substitution of Gelatin Methacryloyl: Best Practice and Current Pitfalls. Biomacromolecules 2018, 19 (1), 42– 52,  DOI: 10.1021/acs.biomac.7b01221
      39
      Quantification of Substitution of Gelatin Methacryloyl: Best Practice and Current Pitfalls
      Claassen, Christiane; Claassen, Marc H.; Truffault, Vincent; Sewald, Lisa; Tovar, Guenter E. M.; Borchers, Kirsten; Southan, Alexander
      Biomacromolecules (2018), 19 (1), 42-52CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)
      Crosslinkable gelatin methacryloyl (GM) is widely used for the generation of artificial extracellular matrix (ECM) in tissue engineering. However, the quantification of modified groups in GM is still an unsolved issue, although this is the key factor for tailoring the physicochem. material properties. In this contribution, 1H-13C-HSQC NMR spectra are used to gain detailed structural information on GMs and of 2-fold modified gelatin contg. methacryloyl and acetyl groups (GMAs). Distinctive identification of methacrylate, methacrylamide, and acetyl groups present in GMs and GMAs revealed an overlap of methacrylamide and modified hydroxyproline signals in the 1H NMR spectrum. Considering this, we suggest a method to quantify methacrylate and methacrylamide groups in GMs precisely based on simple 1H NMR spectroscopy with an internal std. Quantification of acetylation in GMAs is also possible, yet, 2D NMR spectra are necessary. The described methods allow direct quantification of modified groups in gelatin derivs., making them superior to other, indirect methods known so far.
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    40. 40
      Engler, A. J.; Sen, S.; Sweeney, H. L.; Discher, D. E. Matrix Elasticity Directs Stem Cell Lineage Specification. Cell 2006, 126 (4), 677– 689,  DOI: 10.1016/j.cell.2006.06.044
      40
      Matrix elasticity directs stem cell lineage specification
      Engler, Adam J.; Sen, Shamik; Sweeney, H. Lee; Discher, Dennis E.
      Cell (Cambridge, MA, United States) (2006), 126 (4), 677-689CODEN: CELLB5; ISSN:0092-8674. (Cell Press)
      Microenvironments appear important in stem cell lineage specification but can be difficult to adequately characterize or control with soft tissues. Naive mesenchymal stem cells (MSCs) are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity. Soft matrixes that mimic brain are neurogenic, stiffer matrixes that mimic muscle are myogenic, and comparatively rigid matrixes that mimic collagenous bone prove osteogenic. During the initial week in culture, reprogramming of these lineages is possible with addn. of sol. induction factors, but after several weeks in culture, the cells commit to the lineage specified by matrix elasticity, consistent with the elasticity-insensitive commitment of differentiated cell types. Inhibition of nonmuscle myosin II blocks all elasticity-directed lineage specification-without strongly perturbing many other aspects of cell function and shape. The results have significant implications for understanding phys. effects of the in vivo microenvironment and also for therapeutic uses of stem cells.
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    41. 41
      Chen, Y.-C.; Lin, R.-Z.; Qi, H.; Yang, Y.; Bae, H.; Melero-Martin, J. M.; Khademhosseini, A. Functional Human Vascular Network Generated in Photocrosslinkable Gelatin Methacrylate Hydrogels. Adv. Funct. Mater. 2012, 22 (10), 2027– 2039,  DOI: 10.1002/adfm.201101662
      41
      Functional Human Vascular Network Generated in Photocrosslinkable Gelatin Methacrylate Hydrogels
      Chen, Ying-Chieh; Lin, Ruei-Zeng; Qi, Hao; Yang, Yunzhi; Bae, Hojae; Melero-Martin, Juan M.; Khademhosseini, Ali
      Advanced Functional Materials (2012), 22 (10), 2027-2039CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The generation of functional, 3D vascular networks is a fundamental prerequisite for the development of many future tissue engineering-based therapies. Current approaches in vascular network bioengineering are largely carried out using natural hydrogels as embedding scaffolds. However, most natural hydrogels present a poor mech. stability and a suboptimal durability, which are crit. limitations that hamper their widespread applicability. The search for improved hydrogels has become a priority in tissue engineering research. Here, the suitability of a photopolymerizable gelatin methacrylate (GelMA) hydrogel to support human progenitor cell-based formation of vascular networks is demonstrated. Using GelMA as the embedding scaffold, it is shown that 3D constructs contg. human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSCs) generate extensive capillary-like networks in vitro. These vascular structures contain distinct lumens that are formed by the fusion of ECFC intracellular vacuoles in a process of vascular morphogenesis. The process of vascular network formation is dependent on the presence of MSCs, which differentiate into perivascular cells occupying abluminal positions within the network. Importantly, it is shown that implantation of cell-laden GelMA hydrogels into immunodeficient mice results in a rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, it is shown that the degree of methacrylation of the GelMA can be used to modulate the cellular behavior and the extent of vascular network formation both in vitro and in vivo. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.
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    42. 42
      Nichol, J. W.; Koshy, S. T.; Bae, H.; Hwang, C. M.; Yamanlar, S.; Khademhosseini, A. Cell-Laden Microengineered Gelatin Methacrylate Hydrogels. Biomaterials 2010, 31 (21), 5536– 5544,  DOI: 10.1016/j.biomaterials.2010.03.064
      42
      Cell-laden microengineered gelatin methacrylate hydrogels
      Nichol, Jason W.; Koshy, Sandeep T.; Bae, Hojae; Hwang, Chang M.; Yamanlar, Seda; Khademhosseini, Ali
      Biomaterials (2010), 31 (21), 5536-5544CODEN: BIMADU; ISSN:0142-9612. (Elsevier Ltd.)
      The cellular microenvironment plays an integral role in improving the function of microengineered tissues. Control of the microarchitecture in engineered tissues can be achieved through photopatterning of cell-laden hydrogels. However, despite high pattern fidelity of photopolymerizable hydrogels, many such materials are not cell-responsive and have limited biodegradability. Here, the authors demonstrate gelatin methacrylate (GelMA) as an inexpensive, cell-responsive hydrogel platform for creating cell-laden microtissues and microfluidic devices. Cells readily bound to, proliferated, elongated, and migrated both when seeded on micropatterned GelMA substrates as well as when encapsulated in microfabricated GelMA hydrogels. The hydration and mech. properties of GelMA were demonstrated to be tunable for various applications through modification of the methacrylation degree and gel concn. The pattern fidelity and resoln. of GelMA were high and it could be patterned to create perfusable microfluidic channels. Furthermore, GelMA micropatterns could be used to create cellular micropatterns for in vitro cell studies or 3D microtissue fabrication. These data suggest that GelMA hydrogels could be useful for creating complex, cell-responsive microtissues, such as endothelialized microvasculature, or for other applications that require cell-responsive microengineered hydrogels.
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    43. 43
      Malda, J.; Visser, J.; Melchels, F. P.; Jüngst, T.; Hennink, W. E.; Dhert, W. J. A.; Groll, J.; Hutmacher, D. W. 25th Anniversary Article: Engineering Hydrogels for Biofabrication. Adv. Mater. Deerfield Beach Fla 2013, 25 (36), 5011– 5028,  DOI: 10.1002/adma.201302042
      43
      25th anniversary article: Engineering hydrogels for biofabrication
      Malda Jos; Visser Jetze; Melchels Ferry P; Jungst Tomasz; Hennink Wim E; Dhert Wouter J A; Groll Jurgen; Hutmacher Dietmar W
      Advanced materials (Deerfield Beach, Fla.) (2013), 25 (36), 5011-28 ISSN:.
      With advances in tissue engineering, the possibility of regenerating injured tissue or failing organs has become a realistic prospect for the first time in medical history. Tissue engineering - the combination of bioactive materials with cells to generate engineered constructs that functionally replace lost and/or damaged tissue - is a major strategy to achieve this goal. One facet of tissue engineering is biofabrication, where three-dimensional tissue-like structures composed of biomaterials and cells in a single manufacturing procedure are generated. Cell-laden hydrogels are commonly used in biofabrication and are termed "bioinks". Hydrogels are particularly attractive for biofabrication as they recapitulate several features of the natural extracellular matrix and allow cell encapsulation in a highly hydrated mechanically supportive three-dimensional environment. Additionally, they allow for efficient and homogeneous cell seeding, can provide biologically-relevant chemical and physical signals, and can be formed in various shapes and biomechanical characteristics. However, despite the progress made in modifying hydrogels for enhanced bioactivation, cell survival and tissue formation, little attention has so far been paid to optimize hydrogels for the physico-chemical demands of the biofabrication process. The resulting lack of hydrogel bioinks have been identified as one major hurdle for a more rapid progress of the field. In this review we summarize and focus on the deposition process, the parameters and demands of hydrogels in biofabrication, with special attention to robotic dispensing as an approach that generates constructs of clinically relevant dimensions. We aim to highlight this current lack of effectual hydrogels within biofabrication and initiate new ideas and developments in the design and tailoring of hydrogels. The successful development of a "printable" hydrogel that supports cell adhesion, migration, and differentiation will significantly advance this exciting and promising approach for tissue engineering.
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    44. 44
      Wu, Y.; Xiang, Y.; Fang, J.; Li, X.; Lin, Z.; Dai, G.; Yin, J.; Wei, P.; Zhang, D. The Influence of the Stiffness of GelMA Substrate on the Outgrowth of PC12 Cells. Biosci. Rep. 2019, 39 (1), BSR20181748  DOI: 10.1042/BSR20181748
      There is no corresponding record for this reference.
    45. 45
      Chalard, A. E.; Dixon, A. W.; Taberner, A. J.; Malmström, J. Visible-Light Stiffness Patterning of GelMA Hydrogels Towards In Vitro Scar Tissue Models. Front. Cell Dev. Biol. 2022, 10, 946754  DOI: 10.3389/fcell.2022.946754
      45
      Visible-Light Stiffness Patterning of GelMA Hydrogels Towards In Vitro Scar Tissue Models
      Chalard Anais E; Malmstrom Jenny; Chalard Anais E; Malmstrom Jenny; Dixon Alexander W; Taberner Andrew J; Taberner Andrew J
      Frontiers in cell and developmental biology (2022), 10 (), 946754 ISSN:2296-634X.
      Variations in mechanical properties of the extracellular matrix occurs in various processes, such as tissue fibrosis. The impact of changes in tissue stiffness on cell behaviour are studied in vitro using various types of biomaterials and methods. Stiffness patterning of hydrogel scaffolds, through the use of stiffness gradients for instance, allows the modelling and studying of cellular responses to fibrotic mechanisms. Gelatine methacryloyl (GelMA) has been used extensively in tissue engineering for its inherent biocompatibility and the ability to precisely tune its mechanical properties. Visible light is now increasingly employed for crosslinking GelMA hydrogels as it enables improved cell survival when performing cell encapsulation. We report here, the photopatterning of mechanical properties of GelMA hydrogels with visible light and eosin Y as the photoinitiator using physical photomasks and projection with a digital micromirror device. Using both methods, binary hydrogels with areas of different stiffnesses and hydrogels with stiffness gradients were fabricated. Their mechanical properties were characterised using force indentation with atomic force microscopy, which showed the efficiency of both methods to spatially pattern the elastic modulus of GelMA according to the photomask or the projected pattern. Crosslinking through projection was also used to build constructs with complex shapes. Overall, this work shows the feasibility of patterning the stiffness of GelMA scaffolds, in the range from healthy to pathological stiffness, with visible light. Consequently, this method could be used to build in vitro models of healthy and fibrotic tissue and study the cellular behaviours involved at the interface between the two.
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    46. 46
      Norioka, C.; Inamoto, Y.; Hajime, C.; Kawamura, A.; Miyata, T. A Universal Method to Easily Design Tough and Stretchable Hydrogels. NPG Asia Mater. 2021, 13 (1), 34,  DOI: 10.1038/s41427-021-00302-2
      46
      A universal method to easily design tough and stretchable hydrogels
      Norioka, Chisa; Inamoto, Yuino; Hajime, Chika; Kawamura, Akifumi; Miyata, Takashi
      NPG Asia Materials (2021), 13 (1), 34CODEN: NAMPCE; ISSN:1884-4057. (Nature Research)
      Abstr.: Hydrogels are flexible materials that have high potential for use in various applications due to their unique properties. However, their applications are greatly restricted by the low mech. performance caused by high water content and inhomogeneous networks. This paper reports a universal strategy for easily prepg. hydrogels that are tough and stretchable without any special structures or complicated processes. Our strategy involves tuning the polymn. conditions to form networks with many polymer chain entanglements to achieve energy dissipation. Tough and stretchable hydrogels can be prepd. by free radical polymn. with a high monomer concn. and low cross-linker content to optimize the balance between phys. and chem. cross-links by entanglements and covalent bonds, resp. The strategy of using polymer chain entanglements for energy dissipation allows us to overcome the limitation of low mech. performance, which leads to the wide practical use of hydrogels.
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    47. 47
      Foudazi, R.; Zowada, R.; Manas-Zloczower, I.; Feke, D. L. Porous Hydrogels: Present Challenges and Future Opportunities. Langmuir 2023, 39 (6), 2092– 2111,  DOI: 10.1021/acs.langmuir.2c02253
      47
      Porous Hydrogels: Present Challenges and Future Opportunities
      Foudazi, Reza; Zowada, Ryan; Manas-Zloczower, Ica; Feke, Donald L.
      Langmuir (2023), 39 (6), 2092-2111CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      A review. In this feature article, we critically review the phys. properties of porous hydrogels and their prodn. methods. Our main focus is nondense hydrogels that have phys. pores besides the space available between adjacent crosslinks in the polymer network. After reviewing theories on the kinetics of swelling, equil. swelling, the structure-stiffness relationship, and solute diffusion in dense hydrogels, we propose future directions to develop models for porous hydrogels. The aim is to show how porous hydrogels can be designed and produced for studies leading to the modeling of phys. properties. Addnl., different methods that are used for making hydrogels with phys. incorporated pores are briefly reviewed while discussing the potentials, challenges, and future directions for each method. Among kinetic methods, we discuss bubble generation approaches including reactions, gas injection, phase sepn., electrospinning, and freeze-drying. Templating approaches discussed are solid-phase, self-assembled amphiphiles, emulsion, and foam methods.
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    48. 48
      Meesuk, L.; Suwanprateeb, J.; Thammarakcharoen, F.; Tantrawatpan, C.; Kheolamai, P.; Palang, I.; Tantikanlayaporn, D.; Manochantr, S. Osteogenic Differentiation and Proliferation Potentials of Human Bone Marrow and Umbilical Cord-Derived Mesenchymal Stem Cells on the 3D-Printed Hydroxyapatite Scaffolds. Sci. Rep. 2022, 12 (1), 19509,  DOI: 10.1038/s41598-022-24160-2
      48
      Osteogenic differentiation and proliferation potentials of human bone marrow and umbilical cord-derived mesenchymal stem cells on the 3D-printed hydroxyapatite scaffolds
      Meesuk, Ladda; Suwanprateeb, Jintamai; Thammarakcharoen, Faungchat; Tantrawatpan, Chairat; Kheolamai, Pakpoom; Palang, Iyapa; Tantikanlayaporn, Duangrat; Manochantr, Sirikul
      Scientific Reports (2022), 12 (1), 19509CODEN: SRCEC3; ISSN:2045-2322. (Nature Portfolio)
      Mesenchymal stem cells (MSCs) are a promising candidate for bone repair. However, the maintenance of MSCs injected into the bone injury site remains inefficient. A potential approach is to develop a bone-liked platform that incorporates MSCs into a biocompatible 3D scaffold to facilitate bone grafting into the desired location. Bone tissue engineering is a multistep process that requires optimizing several variables, including the source of cells, osteogenic stimulation factors, and scaffold properties. This study aims to evaluate the proliferation and osteogenic differentiation potentials of MSCs cultured on 2 types of 3D-printed hydroxyapatite, including a 3D-printed HA and biomimetic calcium phosphate-coated 3D-printed HA. MSCs from bone marrow (BM-MSCs) and umbilical cord (UC-MSCs) were cultured on the 3D-printed HA and coated 3D-printed HA. SEM and immunofluorescence staining were used to examine the characteristics and the attachment of MSCs to the scaffolds. Addnl., the cell proliferation was monitored, and the ability of cells to differentiate into osteoblast was assessed using alk. phosphatase (ALP) activity and osteogenic gene expression. The BM-MSCs and UC-MSCs attached to a plastic culture plate with a spindle-shaped morphol. exhibited an immunophenotype consistent with the characteristics of MSCs. Both MSC types could attach and survive on the 3D-printed HA and coated 3D-printed HA scaffolds. The MSCs cultured on these scaffolds displayed sufficient osteoblastic differentiation capacity, as evidenced by increased ALP activity and the expression of osteogenic genes and proteins compared to the control. Interestingly, MSCs grown on coated 3D-printed HA exhibited a higher ALP activity and osteogenic gene expression than those cultured on the 3D-printed HA. The finding indicated that BM-MSCs and UC-MSCs cultured on the 3D-printed HA and coated 3D-printed HA scaffolds could proliferate and differentiate into osteoblasts. Thus, the HA scaffolds could provide a suitable and favorable environment for the 3D culture of MSCs in bone tissue engineering. Addnl., biomimetic coating with octacalcium phosphate may improve the biocompatibility of the bone regeneration scaffold.
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  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.biomac.3c00909.

    • Additional experimental details of qualitative observations of structural stability of GelMA-based samples, infrared spectra and thermogravimetric analysis of freeze-dried constructs, and APL/DNA content of GelMA hydrogel samples (PDF)


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