Objective:To observe the effects of low intensity pulsed ultrasound(LIPUS) on the osteogenic differentiation of rat bone marrow mesenchymal stem cells(BMSCs) on titanium surface.Methods:BMSCs from Wistar rat bone marrow were respectively cultured on the flat titanium surface and the large grain blast acid etched(SLA) titanium surface,and induced by mineralization medium.Then,the cells were interfered by LIPUS and a control condition.Alkaline phosphatase(ALP) were quantitative determinated after 3 and 7 d mineralization induction respectively,ALP staining were observed after 14 d induction.Alizarin red staining were observed after 21 d mineralization induction.Osteogenic related protein and gene expressions were detected after mineralization induction.Results:ALP in culture medium of LIPUS group was higher than that of the control group after 3 d and 7 d mineralization induction(P＜0.05).LIPUS group showed stronger ALP staining and alizarin staining,and more mineralized nodules than control group.The expression of osteogenic related proteins,including Runx2,BMP2,OPN in LIPUS group increased.Osteogenic related genes expression,including ALP,Runx2,BMP2,OPN,OCN and Col-1 of the LIPUS group increased.Conclusion:The osteogenic differentiation of BMSCs on the fiat titanium surface or SLA titanium surface can be promoted by LIPUS.

Objective To test the effects of Vitamin D (VitD) on endothelial nitric oxide(NO) production and to study the signal pathway leading to NO release.Methods In vitro cultured human umbilical vein endothelial cells (HUVEC) were treated with various concentrations of VitD(0 mmol/L,0.01 mmol/L,0.10 mmol/L,1.00 mmol/L,10.00 mmol/L) for 60 min,and VitD at concentration of 1.00 mmol/L at different time points (30 min,60 min,90 min,120 min).The effect of VitD on NO production in presence of VitD receptor(VDR) agonist(ZK191784) or antagonist(ZK159222) for 60 min were examined in cell culture supernatant with kit for the detection of nitric oxide fluorescent probe(DAF-FM DA).HUVEC was cultured with VitD in presence of VDR agonist or antagonist for 60 min,and the effect of VitD on NO production with DAF-FM DA and the protein expression and phosphorylation of Caveolin-1 and endothelial nitric oxide synthase(eNOS) were detected by Western blot,respectively.Results VitD caused a concentration-dependent increase in NO production.The maximum effect was observed at a concentration of 1.0 mmol/L and the optimal time of stimulation was 60 min.Effects induced by VitD were enhanced by VDR agonist,and abolished by antagonist.VitD and VDR agonist maintained the expression of Caveolin-1 at the same low phosphorylation level the same as normal,increased the phosphorylated level of eNOS.However,VDR antagonist increased the phosphorylation of caveolin-l,but reduced the level of eNOS phosphorylation,respectively.Conclusions VitD can induce a significant increase in endothelial NO production through VDR.VitD interaction with VDR causes the low phosphorylation of caveolin-1 leading to eNOS activation and NO production.