Therapeutic Extracellular Vesicles from Synovial Fibroblast-Primed MSCs for Osteoarthritis Treatment.

Mesenchymal stem cells (MSCs) migrate to injured tissues through a homing effect and promote tissue regeneration by secreting paracrine factors and extracellular vesicles (EVs) and interacting with resident cells. MSC-derived EVs have emerged as promising therapeutic candidates for osteoarthritis (OA) because they carry bioactive molecules, are easily delivered, and exhibit low immunogenicity. In this study, we generated MSCs with altered cell fate by transferring the microenvironment of SW982 human synovial fibroblast-like cells through direct MSC-synovial fibroblast (SF) interaction and evaluated EVs derived from these cells (miSF-MSC-EVs) as a therapeutic strategy for OA. MSCs and SFs were stained with nuclear dyes, co-cultured for 48 h, and double-positive cells were isolated by fluorescence-activated cell sorting. Proteomic and next-generation sequencing analyses revealed enrichment of miRNAs associated with cell migration, adhesion, and transforming growth factor-β, Wnt, and PI3K signaling pathways in miSF-MSC-EVs. Compared with conventional MSC-EVs, miSF-MSC-EVs enhanced cell proliferation, improved regenerative responses, reduced inflammatory marker expression, and increased anti-inflammatory marker expression in vitro. Furthermore, miSF-MSC-EVs promoted cartilage repair in a mouse OA model, highlighting their potential as a regenerative therapeutic platform for OA treatment.