Cartilage Tissue Engineering Application of Injectable Gelatin Hydrogel with In Situ Visible-Light-Activated Gelation Capability in Both Air and Aqueous Solution

Abstract

Chondroprogenitor cells encapsulated in a chondrogenically supportive, three-dimensional hydrogel scaffold represents a promising, regenerative approach to articular cartilage repair. In this study, we have developed an injectable, biodegradable methacrylated gelatin (mGL)-based hydrogel capable of rapid gelation via visible light (VL)-activated crosslinking in air or aqueous solution. The mild photocrosslinking conditions permitted the incorporation of cells during the gelation process. Encapsulated human-bone-marrow-derived mesenchymal stem cells (hBMSCs) showed high, long-term viability (up to 90 days) throughout the scaffold. To assess the applicability of the mGL hydrogel for cartilage tissue engineering, we have evaluated the efficacy of chondrogenesis of the encapsulated hBMSCs, using hBMSCs seeded in agarose as control. The ability of hBMSCladen mGL constructs to integrate with host tissues after implantation was further investigated utilizing an in vitro cartilage repair model. The results showed that the mGL hydrogel, which could be photopolymerized in air and aqueous solution, supports hBMSC growth and TGF-b3-induced chondrogenesis. Compared with agarose, mGL constructs laden with hBMSCs are mechanically stronger with time, and integrate well with native cartilage tissue upon implantation based on push-out mechanical testing. VL-photocrosslinked mGL scaffold thus represents a promising scaffold for cell-based repair and resurfacing of articular cartilage defects.

Anatomical region-dependent enhancement of 3-dimensional chondrogenic differentiation of human mesenchymal stem cells by soluble meniscus extracellular matrix

“…Expanding on these findings, this study explores the effect of urea-soluble extracts of the inner and outer meniscus ECM in promoting chondrogenic/fibrochondrogenic differentiation of MSCs seeded in a visible light (VL) photocrosslinked methacrylated gelatin (GelMA) hydrogel. GelMA hydrogels have been shown to support robust chondrogenesis of encapsulated MSCs [23] while the use of a VL-activated photoinitiator obviates concerns of UV light-induced mutagenesis or cytotoxicity [24]. We hypothesized that the ECM extracts would promote region-specific cell phenotypes, with the inner and outer ECM extracts respectively enhancing chondrogenic and fibrochondrogenic differentiation of MSCs seeded in GelMA hydrogels.…”

Multilayered polycaprolactone/gelatin fiber-hydrogel composite for tendon tissue engineering

“…To address such restriction on construct thickness, thermo-responsive or chemically initiated crosslinkers may be considered. The VL-based photocrosslinking technique employed in our study is biocompatible, as our previous study found less than 6% cell death in the encapsulated cell population [52]. By combining the two aforementioned characteristics, we have achieved a robust and instant integration of scaffold layers that is compatible with simultaneous, sufficient cell encapsulation.…”

“…Methacrylated gelatin (mGLT) was synthesized using an established protocol with slight modification [29, 34]. Gelatin (GLT, Sigma-Aldrich) was dissolved in deionized H2O at 37 °C (30%, w/v).…”

“…Unlike other types of scaffolds, hydrogels retain a large volume of water and thus provide a highly hydrated environment similar to that in native tissues. Cells encapsulated within collagen/gelatin hydrogels can be easily distributed homogeneously by simple mixing during gel preparation [28, 29]. Importantly, collagen and gelatin, as constituents of natural ECM, better mimic at least in part the native tissue microenvironment, as compared to synthetic polymers [30, 31].…”

Hydrogels and bioreactors for cartilage research and functional tissue engineering

“…However, use of lower wavelengths would likely cause increased damage to irradiated cells. Recently, visible-light photoinitiator such as lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) have been increasingly applied for photopolymerization of cell-laden hydrogels with very good cytocompatibility and short gelation times [421,422]. Since UV irradiation may lead to the formation of reactive oxygen species and subsequent cell damage [423], it is expected that the use of LAP and other visible-light photoinitiators in cartilage tissue engineering applications will further increase in future.…”