FLI1 and PKC co-activation promote highly efficient differentiation of human embryonic stem cells into endothelial-like cells.

Rationale-endothelial cells (ECs) play important roles in various regeneration processes and can be used in a variety of therapeutic applications, such as cardiac regeneration, gene therapy, tissue-engineered vascular grafts and prevascularized tissue transplants. ECs can be acquired from pluripotent and adult stem cells. To acquire ECs from human embryonic stem cells (hESCs) in a fast, efficient and economic manner. We established a conditional overexpression system in hESCs based on 15 transcription factors reported to be responsible for hematopoiesis lineage. Among them, only overexpression of FLI1 could induce hESCs to a hematopoietic lineage. Moreover, simultaneous overexpression of FLI1 and activation of PKC rapidly and efficiently induced differentiation of hESCs into induced endothelial cells (iECs) within 3 days, while neither FLI1 overexpression nor PKC activation alone could derive iECs from hESCs. During induction, hESCs differentiated into spindle-like cells that were consistent in appearance with ECs. Flow cytometric analysis revealed that 92.2-98.9% and 87.2-92.6% of these cells were CD31+ and CD144+, respectively. Expression of vascular-specific genes dramatically increased, while the expression of pluripotency genes gradually decreased during induction. iECs incorporated acetylated low-density lipoproteins, strongly expressed vWF and bound UEA-1. iECs also formed capillary-like structures both in vitro and in vivo. RNA-seq analysis verified that these cells closely resembled their in vivo counterparts. Our results showed that co-activation of FLI1 and PKC could induce differentiation of hESCs into iECs in a fast, efficient and economic manner.