Extracellular vesicles from inflammatory-stimulated BMSCs ameliorate osteoarthritis via Rpl14 mediated synovial macrophage polarization

• iBMSC-EVs attenuates osteoarthritis progression in vitro and in vivo. • iBMSC-EVs facilitates synovial macrophage M1/M2 polarization during OA. • Rpl14 is responsible for iBMSC-EVs mediated synovial macrophage polarization and OA progression. Bone marrow mesenchymal stem cells (BMSCs) and extracellular vesicles (EVs) were considered promising methods for the treatment of diverse diseases, including osteoarthritis (OA). However, the role of inflammatory-stimulated BMSCs driven EVs (iBMSC-EVs) in OA remains unclear. This study aims to investigate the potential function of iBMSC-EVs in ameliorating OA and its underlying molecular mechanism. In this study, EVs were isolated from inflammatory-stimulated BMSCs and destabilization of the medial meniscus (DMM) surgery was performed to induce knee OA model in mice. Micro-CT, H&E Staining, Safranin O-Fast Green Staining and immunofluorescence were used to examine the in vivo therapeutic effect of iBMSC-EVs on OA. Public single-cell RNA-seq data was downloaded and bulk RNA-seq data was acquired to identify critical genes promoted by iBMSC-EVs in macrophage polarization during OA. Real-time quantitative polymerase chain reaction (RT-qPCR), western blot, enzyme-linked immunosorbent assay (ELISA), cell counting kit-8 (CCK-8), transwell and scratch assays were used to further confirm the in vitro effect of iBMSC-EVs on macrophage polarization and chondrocyte proliferation, migration, as well as ECM anabolism and catabolism. In vivo experiments demonstrated that iBMSC-EVs could alleviate OA in mice and promote the reprogramming of M1 macrophages towards an M2 phenotype. RNA-Seq and scRNA-Seq analyses indicated that iBMSC-EVs altered the expression profiles of OA-related genes, with Rpl14 identified as a critical gene regulating macrophage reprogramming in OA. In vivo and in vitro experiments further confirmed that iBMSC-EVs, by downregulating Rpl14 expression, promoted M1 macrophage reprogramming to M2, facilitating chondrocyte proliferation and migration, inhibiting ECM degradation and ultimately alleviating OA progression. In conclusion, our data revealed the substantive role of iBMSC-EVs in ameliorating OA progression via Rpl14 mediated synovial macrophage polarization, presenting a promising therapeutic method for the treatment of OA.