Injectable Gelatin-Silk Fibroin Composite Hydrogels for In Situ Cell Encapsulation

Hydrogels are widely used tools for tissue engineering and regenerative medicine. Characterized as biofunctional, water-based polymer matrices with tunable mechanical properties, hydrogels have promising but limited applications in biomedical engineering, due to poor and static matrix strength. Here we plan to rectify this issue by introducing a new hydrogel made from a composite of gelatin and silk fibroin crosslinked by microbial transglutaminase (mTG) instantly and beta sheet formation gradually, respectively. This interpenetrating network (IPN) shows enhanced mechanical stiffness and strength compared to gelatin hydrogels, and is capable of encapsulating human cells with high viability demonstrated by the encapsulation of human dermal fibroblasts (hDFs). We also demonstrate that this hydrogel can encapsulate mesenchymal stem cells (MSC) as well as differentiate them into osteoblasts by dynamically stiffening the matrix over at 14-day period. These results indicate that this injectable hydrogel can be a great asset for tissue regeneration applications