Mesenchymal stem cell-derived extracellular vesicles promote macrophage efferocytosis and inflammation resolution in osteoarthritis through the miR-21a-5p/YAP1 axis

Abstract

Aim: Osteoarthritis (OA) involves chronic inflammation and cartilage degeneration. Impaired macrophage efferocytosis may contribute to OA progression. This study investigated whether mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) enhance macrophage efferocytosis and inflammation resolution in OA. Methods: Human OA-associated macrophage populations were analyzed using single-cell RNA-sequencing data (GSE220243). In vitro co-culture models combining bone marrow-derived macrophages with apoptotic chondrocytes were used to assess efferocytosis and inflammatory responses. microRNA (miRNA) profiling, luciferase assays, and functional experiments were performed to investigate the miR-21a-5p/YAP1 pathway. Therapeutic effects were assessed using a murine model of medial meniscus destabilization (DMM). Results: Reanalysis of a single-cell transcriptomic dataset revealed an increased proportion of pro-inflammatory macrophage populations and reduced efferocytosis-related signatures in OA samples. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) enhanced macrophage efferocytosis, promoted a pro-resolving inflammatory phenotype, and attenuated chondrocyte damage in vitro. miR-21a-5p was identified as a highly abundant miRNA in MSC-EVs and was reduced in OA human samples. MSC-EV exposure increased miR-21a-5p abundance in macrophages, while miR-21a-5p directly targeted the Yap1 3’-untranslated region (3’-UTR) and modulated efferocytosis-related gene expression, including Gas6, Mertk, and Stab2. YAP1 overexpression counteracted these effects. In the DMM model, MSC-EV treatment and intra-articular administration of miR-21a-5p mimic reduced osteophyte formation, preserved cartilage architecture, lowered Osteoarthritis Research Society International (OARSI) and synovitis scores, and improved inflammatory and efferocytosis-related molecular profiles. Together, these findings support a functional contribution of the miR-21a-5p/YAP1 axis to MSC-EV-associated macrophage regulation and OA protection. Conclusion: MSC-EVs promote macrophage efferocytosis and joint protection in OA through the miR-21a-5p/YAP1 pathway, providing a potential therapeutic strategy for inflammation resolution.