MicroRNA-30a regulates chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells through targeting Sox9

Cartilage injury is difficult to repair since the cartilage tissue lacks self-restoration ability. Improved formation of chondrocytes differentiated from the mesenchymal stem cells (MSC) by genetic regulation is a potentially promising therapeutic option. SOX9 is a critical transcription factor for mesenchymal condensation prior to chondrogenesis. Previous studies demonstrated that several microRNAs (miRNAs or miRs) play a critical role in the chondrogenic differentiation of MSCs. However, the interactional relations between miR-30a and SOX9 during chondrogenic differentiation of MSCs need to be further elucidated. In the present study, human bone marrow-derived mesenchymal stem cells have been isolated and induced into chondrogenic differentiation to imitate the cartilage formation in vitro. Additionally, the expression levels of several miRNAs that were reported to interact with the SOX9 3′untranslated region (UTR) were examined by using reverse transcription-quantitative PCR. The interactional relations between candidate miRNAs and SOX9 were verified with the transfection of a miRNA mimic or inhibitor and a luciferase reporter gene assay. The results indicate that miR-30a and miR-195 were consistently increased during MSC chondrogenic differentiation. Additionally, the binding of miR-30a to the SOX9 3UTR was verified. Then, the authors upregulated the expression of miR-30a and found that MSC chondrogenic differentiation was inhibited. Taken together, the results of the present study demonstrate that miR-30a has a negative regulatory effect on MSC chondrogenic differentiation by targeting SOX9. Advances in epigenetic regulating methods will likely be the future of systemic treatment of cartilage injury.