Coixol-Loaded Hydrogels Promote Osteochondral Defect Repair via Modulation of Ferroptosis and Autophagy in Chondrocytes

Osteoarthritis (OA) is a chronic multifactorial disease characterized by cartilage degeneration, pain, and reduced mobility. Current therapies primarily aim to relieve pain and restore function, but they often have limited effectiveness and side effects. Coixol, a bioactive compound from Coix lacryma-jobi L., exhibits anti-inflammatory and analgesic properties, suggesting potential benefits in OA treatment. This study explored the effects of coixol on OA chondrocytes. Primary chondrocytes from OA rats were isolated and treated with varying concentrations of coixol. Cell viability and proliferation were assessed by using CCK-8 assays. The expression of genes related to ferroptosis and autophagy was analyzed through RT-qPCR, Western blot, and immunofluorescence. Moreover, the study investigated the characteristics and performance of coixol-loaded PDLLA–PEG-PDLLA (PLEL)/gelatin sponge (GS) hydrogels (Coixol@PLEL/GS) for enhancing osteochondral defect repair by specifically targeting chondrocyte ferroptosis and autophagy. The characteristics of coixol-loaded PDLLA–PEG-PDLLA/gelatin sponge (Coixol@PLEL/GS) hydrogels were evaluated using cryo-scanning electron microscopy (SEM) or SEM, and coixol release kinetics were determined. In vivo, a rat osteochondral defect model was used to assess the efficacy of Coixol@PLEL/GS in osteochondral defect repair using International Cartilage Repair Society (ICRS) scores, Safranin O/Fast green staining, Toluidine blue staining, and immunofluorescence. Coixol significantly increased the viability and proliferation of OA chondrocytes in a dose-dependent manner. Furthermore, coixol inhibited ferroptosis and stimulated autophagy, as evidenced by the upregulation of related genes. In vivo, Coixol@PLEL/GS remarkably enhanced the repair of osteochondral defects compared to that of control groups. In conclusion, coixol protects OA chondrocytes by improving survival, inhibiting ferroptosis, and activating autophagy, highlighting its potential as a therapeutic strategy for OA treatment.