An official website of the United States government
Gelatin methacrylate (GelMA) is a photocrosslinkable biomaterial that has gained widespread use in tissue engineering due to its favorable biological attributes and customizable physical and mechanical traits. While GelMA is compatible with various cell types, distinct cellular responses are observed within GelMA hydrogels. As such, tailoring hydrogels for specific applications has become imperative. Thus, our objective was to develop GelMA hydrogels tailored to enhance cell viability specifically for TC28a2 chondrocytes in a three-dimensional (3D) cell culture setting. We investigated GelMA synthesis using PBS and 0.25M CB buffer, analyzed the mechanical and physical traits of GelMA hydrogels, and evaluated how varying GelMA crosslinking conditions (GelMA concentration, photoinitiator concentration, and UV exposure time) affected the viability of TC28a2 chondrocytes. The results revealed that GelMA synthesis using 0.25M CB buffer led to a greater degree of methacrylation compared to PBS buffer, and the LAP photoinitiator demonstrated superior efficacy for GelMA gelation compared to Irgacure 2959. Additionally, the stiffness, porosity, and swelling degree of GelMA hydrogels were predominantly affected by GelMA concentration, while cell viability was impacted by all crosslinking conditions, decreasing notably with increasing GelMA concentration, photoinitiator concentration, and UV exposure time. This study facilitated the optimization of crosslinking conditions to enhance cell viability within GelMA hydrogels, a critical aspect for diverse biomedical applications.
more »
« less
Dual Crosslinked Gelatin Methacryloyl Hydrogels for Photolithography and 3D Printing
Gelatin methacryloyl (GelMA) hydrogels have been used in tissue engineering and regenerative medicine because of their biocompatibility, photopatternability, printability, and tunable mechanical and rheological properties. However, low mechanical strength limits their applications in controlled drug release, non-viral gene therapy, and tissue and disease modeling. In this work, a dual crosslinking method for GelMA is introduced. First, photolithography was used to pattern the gels through the crosslinking of methacrylate incorporated amine groups of GelMA. Second, a microbial transglutaminase (mTGase) solution was introduced in order to enzymatically crosslink the photopatterned gels by initiating a chemical reaction between the glutamine and lysine groups of the GelMA hydrogel. The results showed that dual crosslinking improved the stiffness and rheological properties of the hydrogels without affecting cell viability, when compared to single crosslinking with either ultraviolet (UV) exposure or mTGase treatment. Our results also demonstrate that when treated with mTGase, hydrogels show decreased swelling properties and better preservation of photolithographically patterned shapes. Similar effects were observed when three dimensional (3D) printed and photocrosslinked substrates were treated with mTGase. Such dual crosslinking methods can be used to improve the mechanical properties and pattern fidelity of GelMA gels, as well as dynamic control of the stiffness of tissue engineered constructs.
more »
« less
- PAR ID:
- 10136385
- Date Published:
- Journal Name:
- Gels
- Volume:
- 5
- Issue:
- 3
- ISSN:
- 2310-2861
- Page Range / eLocation ID:
- 34
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
The generation of 3D tissue constructs with multiple cell types and matching mechanical properties remains a challenge in cardiac tissue engineering. Recently, 3D bioprinting has become a powerful tool to achieve these goals. Decellularized extracellular matrix (dECM) is a common scaffold material due to providing a native biochemical environment. Unfortunately, dECM’s low mechanical stability prevents usage for bioprinting applications alone. In this study, we developed bioinks composed of decellularized human heart ECM (dhECM) with either gelatin methacryloyl (GelMA) or GelMA-methacrylated hyaluronic acid (MeHA) hydrogels dual crosslinked with UV light and microbial transglutaminase (mTGase). We characterized the bioinks’ mechanical, rheological, swelling, printability, and biocompatibility properties. Composite GelMA–MeHA–dhECM (GME) hydrogels demonstrated improved mechanical properties by an order of magnitude compared to the GelMA–dhECM (GE) hydrogels. All hydrogels were extrudable and compatible with human induced pluripotent stem cell derived cardiomyocytes (iCMs) and human cardiac fibroblasts (hCFs). Tissue-like beating of the printed constructs with striated sarcomeric alpha-actinin and connexin 43 expression was observed. The order of magnitude difference between the elastic modulus of these hydrogel composites offers applications in in vitro modeling of the myocardial infarct boundary. Here, as a proof of concept, we created an infarct boundary region with control over the mechanical properties along with the cellular and macromolecular content through printing iCMs with GE bioink and hCFs with GME bioink.more » « less
-
Abstract 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 mechanical 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 concentration gels. Herein, the effects of animal source and processing sequence are investigated on scaffold mechanical properties. Hydrogels of 4–6 wt% are characterized. Depending on the temperature 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, respectively. The maximum storage moduli are achieved only by coordinated physical gelation and chemical crosslinking. In this method, the classic thermo‐reversible gelation of gelatin occurs when GelMA is cooled below a thermal transition temperature, which is subsequently “locked in” by chemical crosslinking via photocuring. The effects of coordinated physical gelation and chemical crosslinking are demonstrated by precise photopatterning of cell‐laden microstructures, inducing different cellular behavior depending on the selected mechanical properties of GelMA.more » « less
-
Hydrogels have emerged as a crucial class of materials within the field of tissue engineering. There is growing interest in matching the mechanical properties of hydrogel scaffolds to tissues in the human body and optimizing these properties for cell growth and differentiation. Gelatin methacrylate (GelMA) is a well-accepted, biocompatible hydrogel with tunable mechanical properties. However, the effects of various formulation parameters on its mechanical properties are not well understood. In this study, an array of GelMA scaffold fabrication parameters is evaluated by varying GelMA concentration and ultraviolet light exposure time. Our overarching goal is to characterize the mechanical properties through ultrasound and rheological measurements, providing a framework for GelMA scaffold selection. Pulse-echo ultrasound techniques were used to non-invasively determine the sound speed and attenuation of the scaffolds, revealing significant dependence on GelMA concentration. Steady shear rate and strain- and frequency-controlled oscillatory shear tests using a rotational rheometer (Model: DHR-2, TA Instruments) revealed a range in the levels of shear-thinning as well as viscoelasticity and showed moduli-dependence on both GelMA concentration and light exposure time. Together, this acoustic and rheological characterization can be used to inform the selection of GelMA scaffolds in tissue engineering applications.more » « less
-
Abstract Granular hydrogels show great promise in biomedical applications by mimicking the extracellular matrix and fostering a supportive microenvironment for tissue regeneration. This study investigates how tuning granular hydrogel properties influences lymphatic tube formation. Microgels were fabricated using norbornene‐modified hyaluronic acid (NorHA) via pipetting or vortexing for 90 s (V90s) and 180 s (V180s), then assembled into granular hydrogels under loose and tight packing conditions. These conditions produced gels with varied pore morphologies and bulk rheological properties. Lymphatic capillary formation occurred only in tightly packed gels, where mechanical properties converged, highlighting the importance of gel morphology over stiffness. V180s samples showed earlier vessel formation as seen in lymphatic gene and protein expression, while pipetted gels exhibited greater capillary connectivity, forming larger vessel clusters and fewer small satellite structures. The pipetting gels also supported lower‐curvature, more linear capillary networks that bridged multiple droplets, likely due to reduced entrapment in large voids compared to vortexed gels. These findings suggest that in bulk granular gels, lymphatic tube formation is governed not by mechanical stiffness but by pore size and gel topology (periodicity). Understanding and optimizing these morphological parameters can inform future strategies in lymphatic tissue engineering and regenerative medicine.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/gels5030034
