Although the generation of ETV2-induced endothelial cells (iECs) from human fibroblasts serves as a novel therapeutic strategy in regenerative medicine, the process is inefficient, resulting in incomplete iEC angiogenesis. Therefore, we employed chromatin immunoprecipitation (ChIP) sequencing and identified molecular mechanisms underlying ETV2-mediated endothelial transdifferentiation to efficiently produce iECs retaining appropriate functionality in long-term culture. We revealed that the majority of ETV2 targets in human fibroblasts are related to vasculature development and signaling transduction pathways, including Rap1 signaling. From a screening of signaling pathway modulators, we confirmed that forskolin facilitated efficient and rapid iEC reprogramming via activation of the cyclic AMP (cAMP)/exchange proteins directly activated by cAMP (EPAC)/RAP1 axis. The iECs obtained via cAMP signaling activation showed superior angiogenesis in vivo as well as in vitro. Moreover, these cells could form aligned endothelium along the vascular lumen ex vivo when seeded into decellularized liver scaffold. Overall, our study provided evidence that the cAMP/EPAC/RAP1 axis is required for the efficient generation of iECs with angiogenesis potential.

中文翻译：

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cAMP / EPAC信号传导使ETV2能够诱导血管生成潜力高的内皮细胞。

尽管从人成纤维细胞生成ETV2诱导的内皮细胞（iEC）是再生医学中的一种新型治疗策略，但该过程效率低下，导致iEC血管生成不完全。因此，我们采用了染色质免疫沉淀（ChIP）测序，并确定了ETV2介导的内皮细胞转分化基础的分子机制，以有效地生产在长期培养中保留适当功能的iEC。我们揭示了人类成纤维细胞中大多数ETV2靶标与脉管系统发育和信号转导途径（包括Rap1信号转导）有关。从信号传导途径调节剂的筛选中，我们证实福司柯林通过激活由cAMP（EPAC）/ RAP1轴直接激活的环状AMP（cAMP）/交换蛋白，促进了高效快速的iEC重编程。通过cAMP信号激活获得的iEC在体内和体外均显示出优异的血管生成作用。此外，这些细胞在接种到脱细胞的肝支架中时可以离体形成沿着血管腔的对齐的内皮细胞。总体而言，我们的研究提供了证据，表明cAMP / EPAC / RAP1轴是有效生成具有血管生成潜能的iEC所必需的。