Therapeutic effects of hypoxia-preconditioned cartilage progenitor cell-exosomes on osteoarthritis through autophagy activation and macrophage polarization modulation.

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by progressive cartilage loss, pain, and functional disability. While tissue engineering holds promise for cartilage repair, obtaining high-quality seed cells with optimized functional activity remains a bottleneck. Exosomes derived from cartilage progenitor cells (CPCs) have emerged as potent cell-free therapeutic candidates. Here, we demonstrate that exosomes from hypoxia-preconditioned CPCs (H-Exos) possess superior regenerative capabilities compared to their normoxic counterparts. specifically by promoting proliferation and migration while suppressing catabolism in IL-1β-treated ATDC5 cells. Mechanistically, we show that hypoxic preconditioning enriches miR-222-3p in H-Exos, which targets Rab1A to inhibit mTORC1 signaling and restore autophagy, thereby enhancing chondrocyte anabolism. Notably, we also identified a distinct immunomodulatory function: H-Exos were efficiently internalized by macrophages (RAW264.7), driving their polarization toward an anti-inflammatory phenotype via inhibition of the NF-κB signaling pathway. In a rat OA model, intra-articular delivery of a GelMA/H-Exos composite hydrogel significantly attenuated cartilage destruction and subchondral bone remodeling, concomitant with favorable modulation of synovial macrophage polarization. Collectively, this study elucidates a dual protective mechanism-involving the miR-222-3p-Rab1A-mTORC1-autophagy axis and macrophage reprogramming-and presents a promising biomaterial-based strategy for comprehensive OA therapy.