研究显示内皮祖细胞（EPCs）有助于缺血后的血管新生和组织修复。然而内源性EPCs数量受限，在疾病状态下功能下降。人诱导多能干细胞（hiPSCs）为EPCs提供了很好的来源。目前hiPSCs诱导成EPCs的机制尚未明确，效率仍有待提高。申请者前期工作证实，Gremlin1可促进下肢缺血的修复，该作用与EPCs募集有关（Xiang QL, 2017）；预实验结果显示，在hiPSCs诱导成EPCs的过程中，Gremlin1表达上调，运用CRISPR/Cas9技术敲除Gremlin1，分化显著受抑制。本研究将在细胞水平敲除或过表达Gremlin1，揭示Gremlin1通过拮抗BMP活性和激活VEGFR2通路，从而促进EPCs生成的作用及其机制；并在小鼠下肢缺血模型中，明确Gremlin1在EPCs修复血管中的关键作用和意义，最终为hiPSCs/EPCs治疗缺血性血管性疾病提供科学依据。

Endothelial progenitor cells (EPCs) have been shown to contribute to angiogenesis and tissue repair after ischemia. However, the number of endogenous EPCs is limited and the function is decreased in the disease state. Human induced pluripotent stem cells (hiPSCs) provide a good source of EPCs, and can achieve individualized treatment. At present, the mechanism of hiPSCs induced EPCs is not clear, and the efficiency is still to be improved. Our preliminary work confirmed that Gremlin1 could promote the repair of vascular injury caused by lower limb ischemia, which partly contributed to the recruitment of EPCs (Xiang QL, 2017) .Pre-experimental results showed that expression of Gremlin1 was obviously up-regulated during the differentiation of EPCs induced by hiPSCs. Knockdown of Gremlin1 by CRISPR/Cas9 technology significantly inhibited the differentiation. We will set up cell model of Gremlin1 knockout or overexpression and we plan to reveal the promoting effect and mechanism of Gremlin1 on EPCs formation, whicn through the antagonistic action of BMP and the activation of the VEGFR2 pathway. We also try to clarify the key role and significance of Gremlin1 in EPCs repair in the blood vessels. Finally, we will provide scientific basis for the treatment of ischemic vascular disease by hiPSCs/EPCs.