Metformin promotes differentiation of human bone marrow derived mesenchymal stem cells into osteoblast via GSK3β inhibition.

Objective: Metformin, a common and first-line drug for diabetes mellitus, is widely used in the world. Recently, many studies have documented that osteogenesis could be mediated by metformin. However, the specific mechanism by which metformin affects osteogenesis has not been clearly identified. Therefore, the aim of this study is to evaluate the role of GSK3β in metformin-induced osteogenic differentiation of mesenchymal stem cells (MSCs).

Materials And Methods: Osteoblast-marker genes, including Col-1, OCN, and RUNX2, were measured by RT-PCR in differentiated MSCs treated with Metformin. Osteogenic differentiation viability was measured by Alkaline phosphatase (ALP) assays and Alizarin Red Staining. The expression of GSK3β, β-catenin and AMPK were measured by Western blotting in MSCs treated with metformin.

Results: We found that metformin at 100 μM significantly promoted osteogenic differentiation of human mesenchymal stem cells (hBMSCs). Next, we showed that GSK3β and Wnt signaling pathway are involved in metformin-induced osteogenic differentiation of hBMSCs. Furthermore, osteogenic differentiation of hBMSCs induced by metformin could be eliminated by inhibiting phosphorylation of GSK3β.

Conclusions: The data suggested that metformin promoted the osteoblast differentiation of MSCs by, at least partly, inhibiting GSK3β activity. Additionally, we also found that AMPK plays an essential role in the inhibition of GSK3β by metformin.