Tumor Necrosis Factor-α Inhibits Bone Marrow Stem Cell Differentiation into Osteoblasts by Downregulating microRNA-34a Expression.

OBJECTIVE

In this study, we aimed to investigate the role of microRNAs in modulating osteogenesis in the inflammatory milieu.

METHODS

Bone marrow stem cells were isolated from C57/BL mice. Tumor necrosis factor-alpha (TNF-α) (0-10 ng/ml) was added to the cell medium to mimic an inflammatory reaction. Cell apoptosis and proliferation were evaluated by flow cytometry and CyQUANT direct cell proliferation assay respectively. MicroRNA expression was measured by real-time PCR. Then miR-34a precursors were transfected into BMSCs to evaluate the influence of miR-34a on TNF-α induced suppression.

RESULTS

Our results indicated that TNF-α significantly inhibited BMSC proliferation and differentiation in a dose-dependent manner. In addition, TNF-α significantly decreased mRNA expression level of osteocalcin (OC) and alkaline phosphatase (ALP). TNF-α treatment decreased miR-34a levels, and miR-34a precursors reversed the impact of TNF-α on BMSC proliferation and differentiation.

CONCLUSIONS

Importantly, miR-34a promotes osteogenic differentiation and reverses proinflammatory cytokine influence, indicating that a miR-34a-targeted therapy could be a promising approach to promote bone regeneration.