Targeted Blockage of Pathological Extracellular Vesicles and Particles From Fibroblast‐Like Synoviocytes for Osteoarthritis Relief: Proteomic Analysis and Cellular Effect

Abstract Osteoarthritis (OA), the prevalent debilitating joint disorder, is accelerated by dysregulated intercellular crosstalk, yet the role of fibroblast‐like synoviocyte (FLS)‐derived extracellular vesicles and particles (EVPs) in disease progression remains to be elucidated. Here, integrative analysis of clinical specimens, animal models, and publicly available datasets revealed significant alterations in exosomal pathways within OA synovium. Proteomic profiling revealed distinct molecular signatures in EVPs derived from inflammatory and senescent FLSs, reflecting the pathophysiological status of their parent cells. We demonstrated that FLSs under inflammatory and senescent states in OA secreted pathogenic EVPs that propagated joint degeneration by disrupting chondrocyte homeostasis, polarizing macrophages towards a pro‐inflammatory phenotype, and impairing chondrogenesis of mesenchymal stem cells. To therapeutically target these pathogenic EVPs, we engineered an adeno‐associated virus 9 (AAV9) vector fused with a synovium‐affinity peptide (HAP‐1) to deliver shRNA against Rab27a , a key regulator of EVP secretion. Intra‐articular administration of the engineered AAV9 in a murine OA model induced by destabilization of the medical meniscus significantly reduced synovial hyperplasia, cartilage degradation and inflammatory responses, while demonstrating satisfactory systemic biosafety. Our findings establish FLS‐derived EVPs as critical mediators of OA pathogenesis and propose a targeted strategy to block their secretion, offering a promising disease‐modifying therapeutic avenue for OA.