Effect of metformin on dental pulp stem cells attachment, proliferation and differentiation cultured on biphasic bone substitutes

Objective: To evaluate to the effect of metformin on attachment of human dental pulp stem cells (hDPSCs) and their proliferation and osteogenic differentiation on biphasic hydroxyapatite/beta-tricalcium phosphate granules of macro-porous biphasic calcium phosphate (MBCP). Materials and methods: This in vitro study included four groups: A:hDPSCs + MBCP + Metfromin, B:hDPSCs + MBCP, C:hDPSCs + Metformin and D:hDPSCs (control). Attachment of hDPSCs to bone granules in groups A and B was observed by scanning electron microscopy on days 1 and 7 of cultivation. Cell viability was assessed by MTT assay on days 1, 3, and 7 after cell seeding. Differentiation of the hDPSCs was assessed by measurement of alkaline phosphatase activity on days 3, 7, 14 and 21 after cell culturing in standard and osteogenic media. The data was analyzed by two-way ANOVA at a significance level of p = 0.05. Results: The hDPSCs had firmly attached to the surface of MBCP granules, especially in group A. The MTT values increased in all groups from day 1 to day 7 (p < 0.001). The highest MTT values were observed in group C followed by the control group and groups A and B (p < 0.001). Alkaline phosphatase activity also increased in all groups between days 3 to 21 (p < 0.001) except between days 7 and 14 in standard media (p = 0.094). In standard media, groups with MBCP granules (A and B) showed higher activity (p < 0.05). In osteogenic media, the groups with metformin (A and C) showed higher alkaline phosphatase activity (p < 0.05). Conclusion: This in vitro study showed that 100 Mol/L metformin increased attachment and proliferation of hDPSCs on biphasic granules. Osteogenic differentiation of hDPSCs also increased in the presence of metformin.