Extracellular vesicles from platelet-poor plasma possess anti-inflammatory and anti-catabolic effects in chondrocytes stimulated with IL-1β or synovial membrane-conditioned media.

Background: Although osteoarthritis (OA) is the most prevalent form of arthritis, there is still no effective treatment capable of combining immunomodulatory effects with cartilage repair. Extracellular vesicles (EVs) represent a promising new generation of cell-free therapies for OA. Blood-derived products, including plasma, are an easily available and abundant source of EVs with anti-inflammatory and regenerative properties. In this study, our objective was to analyze the effect of platelet poor plasma-derived extracellular vesicles (PPP-EVs) on stimulated OA chondrocytes in vitro. We hypothesize that PPP from healthy donors could be a suitable source of EVs that can modulate the inflammatory environment of OA chondrocytes.

Methods: Cartilage and synovial membrane (SM) were obtained from patients with OA and whole blood from healthy donors. Synovial membrane-conditioned media (CM / SM) was analyzed using multiplex immunoassays. EVs were isolated from PPP using size exclusion chromatography (SEC) and characterized by nanoparticle tracking analysis (NTA), Western blot, and flow cytometry (FC). The phenotype of the chondrocytes was analyzed using fluorescence microscopy and RT-qPCR. Chondrocytes were stimulated with IL-1β or CM/SM for 24 h. The impact of PPP-EVs on stimulated chondrocyte gene expression was evaluated using RT-qPCR.

Results: The PPP-EVs isolated by SEC were positive for the tetraspanins CD9, CD63, and CD81. The chondrocyte phenotype was confirmed by positive expression of Collagen II and Aggrecane. CM/SM and IL-1β caused inflammatory changes in chondrocytes, which was observed by increased expression of the genes MMP-1, MMP-3 and MMP-13, RANTES, TSG-6, and YKL-40 compared to the control. PPP-EVs added to stimulated chondrocytes for 24 h significantly decreased the expression of the chondrocyte gene YKL-40, TSG-6 and MMP-1.

Conclusions: In this study, we confirmed that PPP is a suitable source of EVs, which can be efficiently isolated by SEC. We found that PPP-EVs were capable of decreasing the expression of inflammatory genes in OA chondrocytes stimulated with IL-1β or CM/SM. This study provides preliminary results on PPP-EVs as an affordable and promising option to modulate the catabolic microenvironment of OA chondrocytes in vitro.