Ang1/Tie2 And VEGF/VEGFR2 Regulate DPSC Function on Stability of Vasculature

Abstract

Objectives: Dental pulp stem cells (DPSCs) are capable of secreting proangiogenic factors to promote postnatal angiogenesis, as well as transforming their phenotype to stabilize the newly formed vessels. However, little is known about the key molecular mechanisms on how DPSCs promote the stability of neovascularization. Methods: DPSCs were directly co-cultured with endothelial cells (ECs) or treated with transforming growth factor beta 1 (TGF-β1) for 7 d. The expression of SMC specific markers, angioponin-1 (Ang1) and vascular endothelial growth factor (VEGF) in E-DPSCs, which were isolated from the EC-DPSC co-cultures using Dynabeads CD31, and T-DPSCs, which were the DPSCs treated by TGF-β1, were assessed by RT-qPCR and western blotting. The contractility of E-DPSCs and T-DPSCs was assessed by functional contraction assay. The effect of E-DPSCs and T-DPSCs on EC sprouting was investigated by 3D sprouting assay. Tie2 and VEGFR2 inhibitors were used to block Ang1/Tie2 and VFGF/VEGFR2 signaling. Results: Expression of SMC specific markers was significantly increased in E-DPSCs and T-DPSCs. The contractility of E-DPSCs and T-DPSCs was greater compared to that of DPSCs. 3D sprouting assay demonstrated that both E-DPSCs and T-DPSCs inhibited EC sprouting. Besides, Tie2 inhibitor reversed the sprouting inhibition by E-DPSCs and T-DPSCs, while VEGFR2 inhibitor boosted the sprouting inhibition by E-DPSCs and T-DPSCs. Conclusions: This study suggests that DPSCs stabilize the newly formed blood vessels via Ang1/Tie2 and VEGF/VEGFR2 signaling.