MicroRNA-664a-5p promotes osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by directly downregulating HMGA2.

Osteogenic differentiation of human bone marrow–derived mesenchymal stem cells (BMSCs) has been regarded as a central issue in fracture healing. MicroRNAs (miRNAs, miRs) participate in diverse physiological processes such as osteoblastic differentiation of BMSCs. In this study, we found that miR-664a-5p was upregulated during osteogenic differentiation of human BMSCs, and this upregulation positively correlated with the expression of osteogenic genes Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), and osteocalcin (OCN). Overexpression of miR-664a-5p promoted the osteogenic differentiation of BMSCs, whereas a knockdown of miR-664a-5p suppressed it. Additionally, high-mobility group A2 (HMGA2) mRNA was identified as a direct target of miR-664a-5p that mediates the function of this miRNA. Overexpression of HMGA2 obviously attenuated miR-664a-5p–induced osteogenic differentiation of BMSCs. Thus, the newly identified miR-664a-5p–HMGA2 pathway expands our understanding of the mechanisms underlying the osteogenic differentiation of human BMSCs, may provide deeper insights into the regulation of this differentiation, and can point to new effective methods for treating osteoporosis.