Driving arterial vascular differentiation of embryonic stem cells through neuropilin-1

Abstract

Characterization of the derived Nrp1+ endothelial progenitor cells (EPCs) reveal that they do indeed express higher levels of many arterial markers, in particular EphrinB2, and lower levels of venous marker, EphB4. Subsequent culture of these sorted populations on Matrigel revealed a highly migratory and network-building behavior of the Nrp1+ cells even in the absence of growth factors. Conversely, the Nrp1- EPCs showed almost no tube/cord formation. The sorted subpopulations were also exposed to fluid shear stress using an IBIDI flow chamber system and a cone-and-plate shear device. When the populations are exposed to shear stress for duration of 24 hours, they both respond by up-regulating EphrinB2 and down-regulating EphB4. However, the Nrp1+ EPCs demonstrated the potential to be more sensitive to mechanical stimuli, and this trend became more noticeable with longer duration of shear stress. In summary, the findings of this research bring a new perspective in isolating vascular progenitor cells; Nrp1+ vascular progenitor cells have the potential to be more responsive to inducers of arterial fate.

Pluripotent stem cells-derived vascular endothelial cells have great potential for vascular tissue engineering applications. However, there are still significant challenges in obtaining a substantial yield of arterial endothelial cells from embryonic stem cells or induced pluripotent stem cells (ESCs and iPSCs) when induced in vitro. In this study, we developed a culture method that promotes the expression of one of the early arterial surface markers: neuropilin-1 (Nrp1). Nrp1 acts as a co-receptor alongside vascular endothelial growth factor receptor-2 (Flk1,VEGFR2). It is a promising marker to investigate as arterial endothelial commitment is dependent on high VEGF-A concentrations, and high Nrp1 expression can potentially indicate the cell’s enhanced response to VEGF and subsequent lean towards an arterial fate. The optimized differentiation protocol reveals that Nrp1 expression is influenced by bone morphogenetic protein 4 (BMP4), by 3D cell-cell interaction, and by hypoxia.