Revisiting matrix hydrogel composed of gelatin and hyaluronic acid and its application in cartilage regeneration.

With the increasing incidence of knee osteoarthritis (KOA), the reparation of cartilage defects is gaining more attention. Given that tissue integration plays a critical role in repairing cartilage defects, tissue adhesive hydrogels are highly needed in clinics. We constructed a biomacromolecule-based bioadhesive matrix hydrogel and applied it to promote cartilage regeneration. The hydrogel was composed of methacrylate gelatin and N-(2-aminoethyl)-4-(4-(hydroxymethyl)-2-methoxy-5-nitroso) butyl amide modified hyaluronic acid (HANB). The methacrylate gelatin provided a stable hydrogel network as a scaffold, and the HANB served as a tissue-adhesive agent and could be favorable for the chondrogenesis of stem cells. Additionally, the chemically modified HA increased the swelling ratio and compressive modulus of the hydrogels. The results of our in vitro study revealed that the hydrogel was compatible with bone marrow stromal cells. In vivo, the hyaluronic-acid-containing hydrogels were found to promote articular cartilage regeneration in the defect site. Therefore, this biomaterial provides promising potential for cartilage repair.