Fig. 4

Exosomal circ_0001236 enhanced hMSC chondrogenesis. a, b hMSC micromass was treated with MSC-Exos and MSC-circ_0001236-Exos at different doses for 14 days. c The circ_0001236 level was detected in the MSC-Exos, MSC-circ_0001236-Exos, and MSC-circ_0001236+miR-3677-3p mimic-Exos groups. The MSC-circ_0001236-Exos (100 μg/mL) group showed stronger Alcian blue (d) and Safranin O (e) and higher Col2a1 (f, I) and Sox9 (g, j) expression, but lower MMP13 (h, k) expression level compared with those incubated with MSC-Exos and MSC-circ_0001236+miR-3677-3p mimic-Exos groups at days 21 with hMSCs induced to chondrogenesis. Moreover, the hMSC-circ_0001236-Exos inhibited MMP13 and enhanced the effect of Col2a1 and SOX9, which is affected by miR-3677-3p (d–k). Upper panels: × 100 magnification; lower panels: magnified view of the area enclosed by black boxes, × 400 magnification (scale bar, 50 μm). The experiment was repeated independently three times, and representative results are shown. GAPDH was used as endogenous control. *P < 0.05, **P < 0.01, ***P < 0.001