Cyclic mechanical strain induces osteogenic differentiation in the coculture system of BMSCs and VECs

Abstract

Abstract: PURPOSE:To detect the effects of cyclic mechanical strain on the coculture system of bone marrow stromal cells(BMSCs)and vascular endothelial cells(VECs)and to clarify the related mechanism. METHODS: Primary BMSCs and VECs were isolated from Sprague-Dawley rats. BMSCs and VECs coculture group, BMSCs monoculture group and VECs monoculture group were exposed to cyclic mechanical strain(6%) by Flexcell 5000 mechanicl loading system. After mechanical loading for 6, 12, 24 and 48h, the mRNA expression of Runx2 and vascular endothelial growth factor(VEGF)were tested by real-time quantitative PCR. VEGF protein in cell culture supernate was quantified using Elisa Kit and alkaline phosphatase(ALP)activity was examined. The VEGFR inhibitor Tivozanib was used to analyze the paracrine role of VEGF. Statistical analysis was performed using SAS 8.0 software package. RESULTS: ①The mRNA expression of Runx2 of coculture group subjected to 6% strain was increased significantly at 6h with 4.3 folds (P<0.05) and ALP activity at 48h with 1.5 folds(P<0.05). ②The mRNA expression of VEGF of coculture group subjected to 6% stain was increased significantly at 12h with 2 folds (P<0.05) and the content of VEGF in cell culture supernate at 12h with 10 folds (P<0.05). Plenty of VEGF was secreted by BMSCs but little by VECs. ③After being subjected to Tivozanib, the expression of Runx2 VECs. ③After being subjected to Tivozanib, the expression of Runx2 of coculture group was decreased by 90% (P<0.05) and ALP activity was decreased by 48% (P<0.05), while those of BMSCs monoculture group were decreased by 30% and 18%, respectively. CONCLUSIONS: Cyclic mechanical strain promotes osteogenic differentiation of BMSCs in the coculture system of BMSCs and VECs, possibly by a paracrine VECs-mediated effect of VEGF on BMSCs.

Key words: BMSCs, VECs, Coculture, Cyclic mechanical strain, Osteogenic differentiation, VEGF

WANG Yu, TANG Guo-hua. Cyclic mechanical strain induces osteogenic differentiation in the coculture system of BMSCs and VECs[J]. Shanghai Journal of Stomatology, 2015, 24(5): 400-404.

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