Supporting data for “Conversion of stem cells from apical papilla into endothelial cells by small molecules and growth factors”.

Incorporating assembled microvascular networks into the bioengineered dental pulp constructs can significantly enhance functional blood circulation and tissue survival after transplantation. Endothelial cells (ECs), the essential cellular building blocks of vascular tissue, play an important role in the process of pre-vascularization. However, obtaining sufficient ECs from a suitable source for translational application is challenging. Dental stem cells (DSCs), which exhibit a robust proliferative ability and immunocompatibility because of their autologous origin, could be a promising alternative cell source for the derivation of endothelial lineages. Under specific culture conditions, DSCs differentiate into osteo/odontogenic, adipogenic, chondrogenic, and neurogenic cell lineages. DSCs also possess the potential to differentiate into endothelial-like cells.

Recently, a new strategy has been developed to directly reprogram one cell type towards another targeted cell type using small molecule compounds modulating epigenetic status and signaling pathways. Human fibroblasts have been chemically reprogrammed into neuronal cells, Schwann cells and cardiomyocyte-like cells by different small molecules combinations. This study aimed to explore whether stem cells from apical papilla (SCAP) could be reprogrammed into endothelial cells (ECs) using the same strategy.

We developed a set of small molecules and growth factors, including VPA, CHIR99021 Repsox, Forskolin, Y-27632, VEGF, BMP-4 and 8-Br-3,5-cAMP, to differentiate SCAP into endothelial linages. The expression level of endothelial specific genes and proteins were assessed by RT-PCR, western blotting, flow cytometry, and immunofluorescence after chemical induction of SCAP. The in vitro functions of SCAP-derived chemical-induced endothelial cells (SCAP-ECs) were evaluated by tube-like structure formation assay, acetylated low-density lipoprotein (ac-LDL) uptake and NO secretion detection. The proliferation and migration ability of SCAP-ECs were evaluated by CCK8 and Transwell assay. LPS stimulation was used to mimic inflammatory environment for demonstrating the ability of SCAP-ECs to express adhesion molecules. The in vivo Matrigel plug angiogenesis assay was performed to assess the function of SCAP-ECs in generating vascular structures using the immune-deficient mouse model.

SCAP-ECs expressed up-regulated endothelial specific genes and proteins, displayed endothelial transcriptional networks, exhibited the ability to form functional tubular-like structures, uptake ac-LDL, secret NO in vitro, and contributed to generate blood vessels in vivo. The SCAP-ECs could also express adhesion molecules in the pro-inflammatory environment and have a similar migration ability like HUVECs. The results indicate that SCAP-ECs could be one promising cell source for vascular engineering and treatment of ischemic diseases.