Metformin facilitates the proliferation, migration, and osteogenic differentiation of periodontal ligament stem cells in vitro

Periodontitis is one of the main causes of tooth loss and has been confirmed as the sixth complication of diabetes. Metformin promotes the osteogenic differentiation of stem cells. Periodontal ligament stem cells (PDLSCs) are the best candidate stem cells for periodontal tissue regeneration. Herein, we aimed to identify the effects of metformin on the proliferation, migration, and osteogenic differentiation of PDLSCs in vitro. PDLSCs were isolated by limiting dilution, and their characteristics were assessed by colony formation assay and flow cytometry. Cell counting and migration assays were used to investigate the effects of metformin on proliferation and migration. The osteogenic differentiation ability of PDLSCs was detected by alkaline phosphatase (ALP) activity and Alizarin Red S staining. Gene and protein levels of osteogenesis-related markers were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis, respectively. Metformin treatment at 10 mu M did not affect PDLSC proliferation, while at 50 and 100 mu M, metformin time-dependently enhanced PDLSC proliferation and significantly increased cell numbers after 5 and 7 days of stimulation (P < 0.05). In addition, 50 mu M metformin exhibited a maximal effect on migration, ALP activity, and mineral deposition (P < 0.05). Furthermore, 50 mu M metformin significantly upregulated the gene expression levels of ALP, BSP, OPN, OCN, and Runx2 and the protein expression of ALP and Runx2 (P < 0.05). In summary, our study confirms that metformin facilitates the proliferation, migration, and osteogenic differentiation of PDLSCs in vitro and could be used as a new strategy for periodontal tissue regeneration.