VEGF/ERK activation and PI3K inhibition together drive a vein-to-artery transition in an in vitro model of human angiogenesis

Artery endothelial cells (ECs) arise through different pathways, including differentiation from mesodermal cells (vasculogenesis) or from already established vein or capillary plexus ECs (angiogenesis), the latter being most common during embryonic development and regeneration. Understanding the vein-to-artery transition could improve revascularization therapies, but progress is limited by a lack of human models. Here, we develop a human pluripotent stem cell (hPSC) differentiation protocol that models the vein-to-artery (v2a) EC conversion. Comparing mesoderm-to-artery (m2a) and v2a transcriptomes with publicly available scRNA-seq data from human embryos showed they reflected vasculogenesis- and angiogenesis-derived artery ECs, respectively. We discovered that full arterial identity could be attained in vein ECs within 48 hours just by activating VEGF signaling while inhibiting PI3K. Overall, we model a critical step in human vascular development and define the minimal signals required for artery differentiation from veins, providing a framework to promote this conversion during revascularization or in therapeutic contexts.