MiR-181d promotes steroid-induced osteonecrosis of the femoral head by targeting SMAD3 to inhibit osteogenic differentiation of hBMSCs.

OBJECTIVE: We aimed to investigate whether miR-181d may be involved in steroid-induced osteonecrosis of the femoral head (ONFH) and its underlying mechanism.

PATIENTS AND METHODS: Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the expression of miR-181d in bone marrow of 5 cases of steroid-induced femoral head necrosis and 5 cases of femoral head necrosis secondary to femoral neck fractures. Marrow-derived mesenchymal stem cells (MSCs) were obtained from bone marrow samples and identified. Subsequently, the effects of miR-181d on osteogenic differentiation were evaluated by alizarin red staining and alkaline phosphatase. Meanwhile, qRT-PCR was performed to detect the levels of osteoblast-specific genes.

RESULTS: The expression of miR-181d in the bone marrow of patients with steroid-induced osteonecrosis of the femoral head was significantly higher than that in the control group. When the expression of miR-181d in MSCs was upregulated, the ALP staining became lighter and the number of calcified nodules, as well as the expression of osteoblast-specific genes, decreased significantly. Meanwhile, the opposite results were observed when miR-181d expression was inhibited. Western blot and luciferase reporting assay proved that miR-181d could negatively regulate the expression of SMAD3.

CONCLUSIONS: MiR-181d can inhibit the differentiation of hBMSCs into osteoblasts by regulating the expression of SMAD3.