M2-sEVs-based immunotherapy for alleviation of osteoarthritis-related pain by regulating synovial macrophage NGF expression via the NOTCH pathway

Osteoarthritis (OA) is a prevalent degenerative joint disease characterized primarily by chronic pain. Currently, there are no highly effective treatments for OA pain. This study aimed to assess the efficacy of M2 macrophage-derived small extracellular vesicles (M2-sEVs) in treating OA and alleviating its associated pain, and to investigate their mechanism of action in pain relief. M2-sEVs were isolated via ultracentrifugation. A sodium iodoacetate-induced rat OA model was established to assess the effects of M2-sEVs. RNA sequencing was utilized to identify the molecular mechanisms underlying these analgesic effects, with subsequent validation experiments conducted via RT-qPCR, Western blot, and ELISA assays. Human end-stage OA synovial tissues cultured ex vivo were also utilized to confirm clinical relevance. M2-sEVs administration alleviated pain behaviors and joint pathology in OA rats, suppressing pain-related molecules in synovium and dorsal root ganglia. Mechanistically, M2-sEVs inhibited synovial macrophage-derived nerve growth factor (NGF) by modulating the Notch pathway. Importantly, this therapeutic mechanism was validated in ex vivo cultured human synovial tissues. M2-sEVs effectively reduce OA-related pain by suppressing macrophage-derived NGF expression via the Notch pathway, highlighting their promising potential as a nanomedicine-based therapeutic strategy for OA pain management.