Fig. 2

CPCs senescence revealed decreased chondrogenesis and increased IL-1β secretion that was correlated with cartilage degeneration. a, b Representative immunofluorescence staining for CD105 (red) and nucleus (blue) (a) and quantitative analysis (b) of primary CPCs and CCs (N = 3 repetitions per group). c, d Representative β-gal staining (c) and positive cell counting of P1 and P10 CPCs (d) (three random fields were selected, N = 3 repetitions per group). e CCK8 assay of P1 and P10 CPCs (N = 3 repetitions per group). f, g Representative macroscopic observation (f) and quantitative analysis (g) by colony formation assay (N = 3 repetitions per group). h–j Representative Saf-O (left), Col 2 (right) staining (h), and quantification (i, j) of P1 and P10 CPCs pellet cultures (n = 6 sections/pellet, N = 3 pellets per group). k, l Representative microscopic images (k) and quantitative analysis (l) by scratch wound healing assay at indicated time points (three random fields were selected, N = 3 repetitions per group). m, n Representative migrated P1 and P10 CPCs (crystal violet staining) (m) and quantification (n) by transwell assay (three random fields were selected, N = 3 repetitions per group). o The IL-1β level in the supernatant during P1 and P10 CPCs pellet cultures by ELISA assay (N = 3 repetitions per group). h, k Scale bar 200 μm. a, c, m Scale bar 50 μm. b, d, g, i, j, n, o Values are shown as mean ± SD. **P < 0.01, ***P < 0.001, ****P < 0.0001, Student’s t test. e, l Values are shown as mean ± SD. NS, no significance; *P < 0.05, ***P < 0.001, ****P < 0.0001, two-way ANOVA with Sidak’s multiple comparisons test