Ang1/Tie2/VE-Cadherin Signaling Regulates DPSCs in Vascular Maturation

Adding dental pulp stem cells (DPSCs) to vascular endothelial cell–formed vessel-like structures can increase the longevity of these vessel networks. DPSCs display pericyte-like cell functions and closely assemble endothelial cells (ECs). However, the mechanisms of DPSC-derived pericyte-like cells in stabilizing the vessel networks are not fully understood. In this study, we investigated the functions of E-DPSCs, which were DPSCs isolated from the direct coculture of human umbilical vein endothelial cells (HUVECs) and DPSCs, and T-DPSCs, which were DPSCs treated by transforming growth factor beta 1 (TGF-β1), in stabilizing blood vessels in vitro and in vivo. A 3-dimensional coculture spheroid sprouting assay was conducted to compare the functions of E-DPSCs and T-DPSCs in vitro. Dental pulp angiogenesis in the severe combined immunodeficiency (SCID) mouse model was used to explore the roles of E-DPSCs and T-DPSCs in vascularization in vivo. The results demonstrated that both E-DPSCs and T-DPSCs possess smooth muscle cell–like cell properties, exhibiting higher expression of the mural cell–specific markers and the suppression of HUVEC sprouting. E-DPSCs and T-DPSCs inhibited HUVEC sprouting by activating TEK tyrosine kinase (Tie2) signaling, upregulating vascular endothelial (VE)–cadherin, and downregulating vascular endothelial growth factor receptor 2 (VEGFR2). In vivo study revealed more perfused and total blood vessels in the HUVEC + E-DPSC group, HUVEC + T-DPSC group, angiopoietin 1 (Ang1) pretreated group, and vascular endothelial protein tyrosine phosphatase (VE-PTP) inhibitor pretreated group, compared to HUVEC + DPSC group. In conclusion, these data indicated that E-DPSCs and T-DPSCs could stabilize the newly formed blood vessels and accelerate their perfusion. The critical regulating pathways are Ang1/Tie2/VE-cadherin and VEGF/VEGFR2 signaling.