We have demonstrated that de novo pulp regeneration can be achieved via stem cell-based approaches. While such progress signifies the ultimate clinical practice of pulp regeneration on patients, one critical issue exists hindering the progress in this field: lack of timely vasculo/angiogenesis rendering inconsistent outcomes and narrowing the cases suitable for such practice (limited to immature teeth with wide open apex). Additionally, the kinetics of neo-vascularization during pulp regeneration is unknown. Without such knowledge, it is difficult to advance to the next level of pulp regeneration. Here, we propose to use combination of angiogenically induced dental pulp stem cells (DPSCs) and non- induced DPSCs to enhance the neo-vascularization during pulp regeneration. Most importantly, we designed a new study model that allows us to conduct real-time kinetic inspection of the cellular process during neo- vascularization under this approach. Overall hypothesis: Combination of angiogenically induced DPSCs and non-induced DPSCs allows accelerated and stabilized neo-vascularization thereby timely blood perfusion with the host vascular system can occur and more complete pulp regeneration can be reached. We will take the advantage of our newly designed tooth fragment skin-fold window chamber model, tube model, as well as our well-established tooth fragment model to test the hypothesis. Below are the Specific Aims. Aim 1. To Investigate the kinetics of the neo-vascularization of pulp regeneration using newly designed study models. • To use combination of angiogenically induced DPSCs that become endothelial-like cells (DPSC-ECs) and non-induced DPSCs for neo-vascularization. • To use tooth fragment skin-fold window chamber model to investigate the enhancement of vascularization and blood perfusion from the host vasculature to the engineered vasculature in real time. Aim 2. To investigate the neo-vascularization mechanism and long-term neo-vascular stability of regenerated pulp. • To examine molecular mechanisms of engineered vasculo/angiogenesis and anastomosis during pulp regeneration using tooth fragment skin-fold window chamber model. • To examine survival and long-term stability of engineered vasculature formed by DPSC-ECs plus DPSCs as well as the quality/quantity of the regenerated pulp in the tooth fragment model. The success of this project will allow this field to move closer to clinical applications, and potentially establishing a technology widely used in clinical endodontics.