Efficient direct reprogramming of c-Kit- mature amniotic cells into endothelial cells by ETS factors and TGFß suppression

ETS transcription factors ETV2, FLI1 and ERG1 specify pluripotent stem cells into endothelial cells (PSC-ECs). However, these PSC-ECs are unstable and often drift towards non-vascular cell fates. We show that human mid-gestation c-Kit- lineage-committed amniotic cells (ACs) can be reprogrammed into induced vascular endothelial cells (rAC-VECs). Transient ETV2 expression in ACs generated immature iVECs, while co-expression with FLI1/ERG1 endowed rAC-VECs with a vascular repertoire and morphology matching mature ECs. Brief TGFb-inhibition functionalizes VEGFR2 signaling, augmenting specification of ACs into rAC-VECs. Genome-wide transcriptional analyses showed that rAC-VECs are similar to adult ECs in which vascular-specific genes are expressed and non-vascular genes are silenced. Functionally, rAC-VECs form stable vasculature in Matrigel plugs and regenerating livers. Thus, short-term ETV2 expression and TGFb-inhibition along with constitutive ERG1/FLI1 co-expression reprogram mature ACs into generic rAC-VECs with clinical-scale expansion potential. Public banking of HLA-typed rAC-VECs would establish a vascular inventory for treatment of genetically diverse disorders. Overall design: Transcriptome sequencing of clonal and non-clonal rAC-VECs, HUVECs, LSECs, CD34+/Lin-, BMS