Hydroxypropyl chitin-oxidized chondroitin sulfate double-network hydrogel assists microfracture technique to enhance cartilage regeneration

Cartilage has limited self-repair ability, leading to osteoarthritis postinjury and ultimately physical disability in people. In addition, cartilage injury is accompanied by loss of extracellular matrix (ECM) and infiltration of inflammation, which makes cartilage regeneration more difficult. In this study, a hybrid hydrogel of hydroxypropyl chitin and oxidized chondroitin sulfate (HPCH-OCS) with injectable and thermosensitive properties was prepared by a Schiff base reaction. In vitro, the HPCH-OCS hydrogel showed desirable biocompatibility and bioactivity by promoting chondrogenic differentiation of stem cells, maintaining the chondrocyte phenotype, and inhibiting proteins related to cartilage ECM catabolism under inflammatory conditions. In vivo, the HPCH-OCS hydrogel combined with microfracture could effectively repair cartilage defects and promote cartilage regeneration. In conclusion, the HPCH-OCS hydrogel has good biological and mechanical properties, and its combination with microfracture provides an effective strategy for clinical cartilage regeneration.