Investigation of the effects of Si-A/PUE@HA hydrogels on the osteochondral defect microenvironment based on single-cell RNA sequencing.

Osteochondral defects pose significant challenges in joint health, leading to pain, decreased mobility, and substantial healthcare costs due to surgical interventions. This study aimed to develop and evaluate Si-A/PUE@HA composite hydrogels as scaffolding materials for cartilage tissue engineering, addressing the limitations of current treatment options. Utilizing a multi-step synthesis method that incorporates both chemical and physical crosslinking techniques, we assessed the hydrogels' cytocompatibility, chondrogenic differentiation potential, immunomodulatory properties, and in vivo cartilage regeneration capabilities. In vitro results demonstrated high cell viability and proliferation rates of bone marrow mesenchymal stem cells (BMSCs) cultured in Si-A/PUE@HA hydrogels, with significant expression of chondrogenic markers such as Acan, Sox9, and Col2a1. Notably, the hydrogels exhibited a favorable immunomodulatory effect, promoting an anti-inflammatory M2 macrophage phenotype, which is crucial for tissue regeneration. In vivo studies confirmed substantial new tissue formation and integration with surrounding cartilage, as evidenced by micro-CT analysis, alongside excellent biocompatibility with no significant adverse effects observed in major organs over a 12-week period. Single-cell RNA sequencing analysis revealed a favorable immune microenvironment and enhanced chondrogenesis linked to hydrogel treatment. In conclusion, Si-A/PUE@HA hydrogels represent a promising biomaterial with potential applications in cartilage repair and regenerative medicine, warranting further investigation in larger clinical trials to validate their efficacy and safety for future therapeutic use.