Dentin matrix affects VEGF & VEGF-R2 expression in endothelial cells

Angiogenesis is a key process in the development of organs during embryogenesis and also, in wound healing. Our recent studies demonstrated that dentin matrix components (DM) had angiogenic effects in a dose-dependent manner in an endothelial-fibroblast cell co-culture system suggesting that the angiogenic growth factors sequestrated in dentin matrix released after injury may contribute to the local angiogenesis and reparative response. Objectives: To investigate whether VEGF&VEGF receptor 2 (KDR) mediated such angiogenic effects. Methods: EDTA-solubilised human dentin matrix components were prepared with 10% EDTA, pH 7.2 in the presence of protease inhibitors. Human umbilical vein endothelial cells (HUVECs) were cultured with supplemented medium in the presence or absence of DM (0.0001-1mg/ml). Total RNA from each group was extracted at day 9 of culture and semi-quantitative RT-PCR was subsequently performed with the house-keeping gene-glyceraldehyde-3- phosphate dehydrogenase (GAPDH) as an internal control. Results: 353bp transcripts of human VEGF and 373bp KDR were cloned from HUVECs cultured with or without DM. The expression of both genes changed in a dose-dependent manner. They were gradually increased in cultures with DM at lower concentrations (0.0001-0.01mg/ml) and decreased at higher concentrations of 0.1 & 1 mg/ml compared to the medium control. Conclusion: Dentin matrix components can affect the expression of VEGF and KDR in endothelial cells in a dose-dependent manner suggesting that both genes mediate the angiogenic effects during repair in the dentin-pulp complex.