Extracellular vesicles derived from engineered BMSCs improve damaged cartilage in mice with osteoarthritis by delivering PBX1

BACKGROUND: The beneficial effects of bone marrow mesenchymal stem cells (BMSCs) have been linked to their secreted extracellular vesicles (EVs). These EVs can suppress cartilage degradation and prevent apoptosis in articular cells. We aimed to explore the therapeutic efficacy of engineered BMSCs-EVs in the treatment of osteoarthritis (OA). METHODS: The isolation of BMSC-derived EVs was conducted via ultracentrifugation techniques, followed by characterization. Engineered EVs were obtained by transfecting chondrocyte-affinity peptide (CAP) and Pre-B-cell leukemia transcription factor 1 (PBX1) expression plasmids into BMSCs. OA injury was induced by the treatment of chondrocytes with IL-1β, and the OA mouse model was established by DMM surgery. The efficacy of different EVs was examined in vitro and in vivo. EVs treatment and combined genetic interventions were performed in vitro and in vivo. RESULTS: Both CAP modification and increased protein loading of PBX1 strengthened the protective effect of EVs on chondrocytes and ameliorated OA-induced cartilage damage. PBX1 promoted extracellular signal-regulated kinase (ERK) signaling and the expression of the downstream molecule c-FOS in chondrocytes by activating the transcriptional expression of calcium channel voltage-dependent subunit beta 4 (CACNB4). The chondroprotective effect of engineered EVs was significantly attenuated by inhibiting CACNB4/ERK signaling in IL-1β-treated chondrocytes, as well as in the DMM-induced mouse model. CONCLUSION: Engineering (CAP modification and increased PBX1 protein loading) enhances the therapeutic efficacy of BMSCs-EVs on chondrocytes, which depends on the activation of the CACNB4/ERK signaling. Engineered EVs represent a promising treatment for OA cartilage damage.