Gluteal adipose-derived stem cell exosomes promote macrophage polarization and cartilage regeneration in osteoarthritis via PTPRC modulation

BACKGROUND: Osteoarthritis (OA) is a progressive joint disease characterized by cartilage degradation, synovial inflammation, and limited regenerative capacity. Adipose-derived stem cell exosomes (ADSC-Exo) represent a promising cell-free therapeutic approach due to their immunomodulatory properties. METHODS: Gluteal ADSC-Exo were isolated and characterized by nanoparticle tracking analysis and Western blotting. Their effects were evaluated in vitro in human chondrocytes, fibroblast-like synoviocytes, and THP-1-derived macrophages using proliferation, migration, immunofluorescence, Seahorse metabolic analysis, and RNA sequencing. In vivo, OA was induced in mice by destabilization of the medial meniscus (DMM) and treated with ADSC-Exo, a protein tyrosine phosphatase receptor type C (PTPRC/CD45) inhibitor alone, or in combination. Cartilage pathology and inflammation were assessed by histology, Osteoarthritis Research Society International (OARSI) scoring, immunohistochemistry, and enzyme-linked immunosorbent assays. CRISPR/Cas9-mediated deletion of PTPRC was performed in M1-polarized macrophages to validate mechanistic involvement. RESULTS: ADSC-Exo enhanced cell proliferation, migration, and extracellular matrix gene expression while suppressing catabolic markers under inflammatory conditions. ADSC-Exo promoted macrophage polarization toward an anti-inflammatory M2 phenotype, reduced pro-inflammatory cytokine production, and shifted macrophage metabolism toward oxidative phosphorylation. Transcriptomic analysis identified PTPRC as a consistently downregulated target. Genetic deletion of PTPRC attenuated inflammatory and glycolytic gene expression and reduced chondrocyte catabolic responses. In the DMM model, ADSC-Exo preserved cartilage structure, reduced OARSI scores, and suppressed synovial PTPRC expression and inflammatory mediators; these effects were selectively attenuated by PTPRC inhibition. CONCLUSION: Gluteal ADSC-Exo exert potent anti-inflammatory and chondroprotective effects through immunometabolic reprogramming of macrophages, with PTPRC identified as a key mediator, supporting their translational potential for OA therapy.