Fig. 4

C-EVs promote the chondrogenic differentiation of HUCMSCs. The expression levels of chondrocyte-specific markers Col2a, ACAN, and Sox9 (a), the hypertrophic cartilage marker Col10, and the fibrocartilage marker Col1a (b) in C-EVs-stimulated HUCMSCs were determined using RT-PCR analysis. These data are presented as the mean ± SD of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. c The amount of COL2A, SOX9, ACAN, COL1A, and COL10 protein was determined using western blot analysis of HUCMSCs 21 days after treatment with PBS, C-EVs, or TGF-β. GAPDH was used as a loading control. d The quantification of DNA and GAG was performed using biochemical assays, and the ratio of GAG/DNA was calculated. HUCMSCs were cultured with PBS, C-EVs, or TGF-β for 3, 7, 14, and 21 days. These data are presented as the mean ± SD of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. e Immunofluorescence staining for COL2A in HUCMSCs treated with or without C-EVs in vitro. Scale bar = 500 μm. f Quantitative results of immunofluorescence in e, *p < 0.05, **p < 0.01, ***p < 0.001