Injectable hydrogels from enzyme-catalyzed crosslinking as BMSCs-laden scaffold for bone repair and regeneration

Bone-marrow-derived mesenchymal stem cells possess great potential for tissue engineering and regenerative medicine. In the work, an injectable BMSCs-laden hydrogel system was formed by enzyme-catalyzed crosslinking of hyaluronic acid-tyramine and chondroitin sulfate-tyramine in the presence of hydrogen peroxide and horseradish peroxidase, which was used as a 3D scaffold to explore the behavior of the mesenchymal stem cells. Afterward, the gelation rate, mechanical properties, as well as the degradation process of the scaffold were well characterized and optimized. Furthermore, bone morphogenetic protein-2 was encapsulated in the scaffold, which was used to improve the osteogenic properties. The results illustrated that such a BMSCs-laden hydrogel not only offered a proper microenvironment for the adhesion, proliferation and differentiation of mesenchymal stem cells in vitro, but also promoted bone regeneration in vivo. Therefore, this injectable BMSCs-laden hydrogel may serve as an efficient 3D scaffold for bone repair and regeneration.