Sca-1+ progenitors derived from embryonic stem cells differentiate into endothelial cells capable of vascular repair after arterial injury

Background - Embryonic stem cells possess the ability to differentiate into endothelium. The ability to produce large volumes of endothelium from embryonic stem cells could provide a potential therapeutic modality for vascular injury. We describe an approach that selects endothelial cells using magnetic beads that may be used therapeutically to treat arterial injury. Methods and Results - Large numbers of endothelial cells (ECs) with high purity were produced using Sca-1(+) cells isolated with magnetic beads from predifferentiated embryonic stem cells (ESCs) cultured in alpha-MEM containing 10 ng/mL VEGF(165) for a minimum of 21 days (esEC). The transcription regulator histone deacetylase (HDAC3) was essential for VEGF-induced EC differentiation. Immunofluorescence or fluorescence-activated cell sorter (FACS) analysis revealed that esECs expressed a full range of EC lineage-specific markers including CD31, CD106, CD144, Flk-1, Flt-1, and von Willebrand factor (vWF). FACS analysis confirmed that 99% of esECs were CD31-positive and 75% vWF-positive. Furthermore, almost all cells were positive for DiI-acLDL uptake. When matrigel containing esECs was subcutaneously implanted into mice, various vessel-like structures were observed indicating their endothelial cell like phenotype. In keeping with this, when esECs infected with adenovirus-LacZ were injected into denuded femoral arteries of mice, they were found to form a neo-endothelium that covered the injured areas (86% +/- 13.6%), which resulted in a 73% decrease in neointimal area 2 weeks after injury. Conclusions - We conclude that Sca-1(+) cells can differentiate into functional ECs via activation of HDAC3, accelerating re-endothelialization of injured arteries and reducing neointima formation.