SOX17/ETV2 improves the direct reprogramming of adult fibroblasts to endothelial cells

An autologous source of vascular endothelial cells (ECs) is valuable for vascular regeneration and tissue engineering without the concern of immune rejection. The transcription factor ETS variant 2 (ETV2) has been shown to directly convert patient fibroblasts into vascular EC-like cells. However, reprogramming efficiency is low and there are limitations in EC functions, such as eNOS expression. In this study, we directly reprogram adult human dermal fibroblasts into reprogrammed ECs (rECs) by overexpressing SOX17 in conjunction with ETV2. We find several advantages to rEC generation using this approach, including improved reprogramming efficiency, increased enrichment of EC genes, formation of large blood vessels carrying blood from the host, and, most importantly, expression of eNOS in vivo. From these results, we present an improved method to reprogram adult fibroblasts into functional ECs and posit ideas for the future that could potentially further improve the reprogramming process.