Fig.4.

Protective effect of M2 macrophages induced by hUCMSCs-EVs on OA chondrocytes in vitro. A IL-1β-induced OA chondrocytes were co-cultured with the supernatant of M2 macrophages (M2S) induced by hUCMSCs-EVs, or platelet-rich plasma (PRP) for 48 h, relative mRNA expression of the key genes TNF-α, MMP13, SOX9, and ACAN was measured by quantitative RT-PCR analysis; the experiment was performed triplicate; *p < 0.05, **p < 0.01, ***p < 0.001. B Western blot was performed to evaluate the expression of TNF-α, MMP13, and IL-4 proteins in PBS, M2S, or PRP-treated OA chondrocytes; GAPDH was employed as the loading control; *p < 0.05, **p < 0.01, ***p < 0.001. C The influence of M2S or PRP on the viability of chondrocytes was detected by the cell live/death experiment; green represents live cells while red represents dead cells; Scale bar: 1 mm