Boron-assisted dual-crosslinked poly (γ-glutamic acid) hydrogels with high toughness for cartilage regeneration.

Although mesenchymal stem cells (MSCs) encapsulated with bionic scaffolds have been widely used in treating trauma induced cartilage defects, challenges still persist for these hydrogel scaffolds to create suitable shelters for the MSCs and guide their behaviors. In this work, novel biomimetic hydrogel scaffolds were prepared by thiol-ene Michael addition between glycidyl methacrylate (GMA)-modified poly (γ-glutamic acid) (γ-PGA-GMA) and DL-1,4-Dithiothreitol (DTT) for cartilage tissue engineering. Sodium tetraborate decahydrate was added into the system to connect with DTT through hydrogen-bond interaction and served as catalyst for thiol-ene Michael addition to strengthen the intensity of the hydrogel. The hydrogels could be compressed to nearly a 90% strain, with 0.95 MPa compression stresses which was better than that of most hydrogels in mechanical property. Additionally, this hydrogel has other properties: fast and controlled gel-forming speed, adjustable swelling ration, suitable interior structure and so on. Above all, hydrogels have excellent cyto/tissue-compatibility. Cells cultured in hydrogels in vitro exhibited good proliferation and adhesion abilities and the hydrogels scaffolds contained stem cells immensely accelerated the regeneration of auricular cartilage of rabbits in vivo versus control group. The overall results approved that this bionic hydrogel may be a promising biomaterial for cartilage regeneration in the future.