NOS2 and osteoarthritis: Some researchers have also found that TGF-β is an effective inducer of chondrocyte anabolism, and BMSCs-Exos treated with TGFβ3 significantly up-regulated the expression of chondrogenic genes (COL1, COL2B, and ACAN) in osteoarthritis and down-regulated inflammatory marker genes (MMP-13, ADAMTS5, and iNOS), which protected chondrocytes from apoptosis and inhibited macrophage activation; therefore, they presented cartilage-protective and anti-inflammatory properties, preventing the development of osteoarthritis in mice [114].