Rutin protects human periodontal ligament stem cells from TNF-α induced damage to osteogenic differentiation through suppressing mTOR signaling pathway in inflammatory environment

Objectives: To investigate whether rutin could protect human periodontal ligament stem cells (hPDLSCs) from TNF-alpha induced damage to osteogenic differentiation in inflammatory environment and detect the underlying mechanism. Materials and methods: hPDLSCs were identified by flow cytometery. TNF-alpha was used to stimulate hPDLSCs to establish an inflammation model in vitro. Alkaline phosphatase (ALP) staining, ALP activity test, and Alizarin Red staining were used to detect the changes of osteogenic differentiation ability. The mRNA and protein levels of osteogenic genes were evaluated by RT-PCR and Western Blot. The expression of mTOR was also detected by Western Blot. Results: hPDLSCs were positive to MSCs specific surface markers. The inflammatory environment in vitro could be established by stimulating hPDLSCs with TNF-alpha (20 ng/mL). TNF-alpha (20 ng/mL) could decrease the ALP activity and mineralization ability of hPDLSCs and down-regulate the expression of osteogenic genes in inflammatory environment. Moreover, rutin could affect TNF-alpha (20 ng/mL) induced damage to osteogenic differentiation of hPDLSCs in a dose-dependent manner, 10 mu mol/L rutin could significantly reverse the damage caused by TNF-alpha. In addition, rutin inhibited TNF-alpha-activated mTOR signal transduction by inhibiting the phosphorylation of mTOR, similar to the effects of rapamycin(a specific mTOR inhibitor). Conclusions: Rutin could protect hPDLSCs from TNF-alpha induced damage to osteogenic differentiation in inflammatory environment, and rutin is expected to become a new candidate drug for the treatment of bone defect of periodontitis.