Small extracellular vesicles (sEVs; also known as exosomes) might modulate the joint microenvironment by delivering mRNAs, microRNAs (miRNAs) or other small non-coding RNAs to cartilage cells. Asghar et al. sought to characterize the potential cellular source and genetic cargo of sEVs found in the synovial fluid of individuals with osteoarthritis (OA).

Cultured synovial fibroblasts from individuals with OA produced sEVs with the ability to alter gene expression in primary chondrocytes from the same individuals. The uptake of sEV by OA chondrocytes impaired cell viability and increased the production of pro-inflammatory cytokines. Moreover, sEVs from cultured OA synovial fibroblasts increased the catabolism of extracellular matrix in cartilage explants from individuals with OA.