Fig. 5.

Exosomal circ_0001236 promotes cartilage-specific gene expression by sponging miR-3677-3p in human chondrocytes. a–c Expression of circ_0001236 and miR-3677-3p in healthy and OA cartilage by fluorescence in situ hybridization. d, e Relative exosomal circ_0001236 and miR-3677-3p expression levels in healthy and OA cartilage tissue and secreted exosomes were determined by qRT-PCR. GAPDH was used as endogenous control. Each dot represents a value from a single experiment involving a single donor. f, g The protein expression of Col2a1, Sox9, and MMP13 in OA chondrocytes were treated by MSC-circ_0001236-Exos (50 μg/mL, 100 μg/mL) and MSC-Exos (50 μg/mL). GAPDH was used as an endogenous control in western blotting. Immunohistochemistry analysis of Col2a1 (h, i), Sox9 (h, j), and MMP13 (h, k) is shown in OA chondrocytes, which were treated with hMSC-Exos, hMSC-circ_0001236-Exos, and hMSC-circ_0001236+miR-3677-3p mimic-Exos. The immunohistochemistry results were consistent with the western blot analysis. The experiment was repeated independently three times, and representative results are shown. GAPDH and U6 were used as endogenous control. *P < 0.05, **P < 0.01, ***P < 0.001