Extracellular vesicles as novel approaches for the treatment of osteoarthritis: a narrative review on potential mechanisms.

Osteoarthritis (OA) is a progressive degeneration of articular cartilage with involvement of synovial membrane, and subchondral bone. Current treatment approaches have focused on controlling the OA symptoms, pain, and inflammation. Recently, cell-based therapies, including the application of stem cells such as mesenchymal stem cells (MSCs), have been introduced for restoration of the articular cartilage. Despite promising outcomes, there are some limitations in the application of MSCs for OA treatment. It has been demonstrated that the regenerative potential of stem cells is related to the production of paracrine factors. Extracellular vehicles (EVs), the main component of cell secretome, are membrane-bounded structures that deliver biologically active agents. The delivery of molecules (e.g., nucleic acids, proteins, and lipids) leads to cell-to-cell communication and the alteration of cell functions. In this review, general characteristics of EVs, as well as their potential mechanisms in the prevention and treatment of OA were considered. Based on in vitro and in vivo studies, EVs have shown to contribute to cartilage regeneration via suppression of degenerative factors and regulation of chondrocyte function in the synthesis of extracellular matrix components. Also, they inhibit the progression of OA or protect the cartilage from degradation via their impact on inflammatory cytokines. The different signaling pathways of EVs against the pathologic features of OA were summarized in this review. According to the results obtained from several investigations, more investigations should be design to prove the safety and effectiveness of EVs in the treatment and prevention of OA progression.