Objective To explore the effect of Notch1 signal pathway on the osteogenic differentiation in human periodontal ligament stem cells(PDLSCs) under dynamic strain.Methods PDLSCs were separated from freshly extracted teeth then identified and prolifed.Notch1 signal pathway was regulated by chemicals.Dynamic strains were applied to PDLSCs with the tension plus system.Then Notch1 signal pathway key factor Notch intracellular domain(NICD),osteoblastic related indexes alkaline phosphatase(ALP) and bone morphogenetic proteins 2 (BMP2) were detected by western blot expression.The deformation rate of stress parameters was 0 to 12%,and the frequency was 0.1 Hz.The loading time was 0 h,6 h,12 h and 24 h.Results As Notch1 signal pathway was activated,the expression of osteogenic markers ALP and BMP2 both reduced (P<0.05).On the contrary, the expression of osteogenic markers ALP and BMP2 both increased obviously (P<0.05) as Notch1 signal pathway was inhibited.Conclusion The activated Notch1 signal pathway will inhibit osteogenic differentiation of PDLSCs under dynamic tensile.

Objective To investigate the effect of β-catenin on the osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) under mechanical tension.Methods PDLSCs were seperately cultured in vitro from the periodontium attached at freshly extracted teeth.β-catenin-targeting agonist or inhibitor was applied to the PDLSCs to upregulate or downregulate the expression of activity of β-catenin protein.The expression of β-catenin protein and the osteogenetic related markers(ALP,BMP2,Runx 2) under the mechanical tension with different period(0,6,12,24 h) were assessed with Western blot in the PDLSCs irritated with agonist or inhibitor.Results Compared with the PDLSCs without mechanical tension,the expression of osteogenesis related marker proteins,ALP and Runx 2,in PDLSCs were enhanced under the circular mechanial tensile stress (P ＜ 0.05).In the PDLSCs irritated with WAY-262611,the β-catenin-targeting agonist,the expression of osteogenetic related markers ALP in the PDLSCs was improved during the first 12 h period of mechnical tensile load,which was significantly higher than that in the DMSO group.Conclusion Wnt/β-catenin signaling pathway plays an important role in the early osteogenesis differentiation of PDLSCs under cyclic tension.The β-catenin promotes osteogenic differentiation of PDLSCs under mechanical tension.