Foxc2通过调控整合素介导的募集增强内皮祖细胞促内皮修复作用的研究

Maintenance of endothelial integrity and promotion of early re-endothelialization are of paramount importance for reducing cardiovascular diseases and the post-intervention complications. Accumulating evidences suggest that endothelial progenitor cells (EPCs) mobilized or transfused are capable of facilitating endothelial repair through direct differentiation into endothelial cells and/or via the paracrine mechanisms. The vasoregenerative effects of EPCs depend on their recruitment into the vascular injury sites.Indeed, the number of recruited EPCs appears to be related to their circulating numbers but also the functional properties of EPCs homing. Studies show that integrins is the key molecules in regulating EPCs homing and recruitment. Emerging evidences exist for the impaired integrin-dependent recruitment and the low engraftment of EPCs due to some risk factors for coronary artery disease. These underline the need for new strategies capable of increasing the integrin-mediated homing potential of EPCs. The Foxc2 protein, a member of the Forkhead/Fox transcription factor family, is essential for the cardiovascular system. Foxc2 is recognized as a novel regulator of angiogenesis via induction of CXCR4 and angiopoietin-2 expression. Notably, Foxc2 directly induces the expression of integrin ?3 in endothelial cells. Recently, it is accepted that the phenotypic and functional behavior of endothelial colony forming cells (ECFCs, also called "late" EPCs) is very similar to mature endothelial cells. Until now there are no data showing the effects of Foxc2 on the functional properties of EPCs. Based on the effects of Foxc2 on the properties of endothelial cells, we sought to determine whether Foxc2 may affect integrin ?3 expression and the recruitment capacity of EPCs as well as the EPCs-mediated endothelial repair.

内皮祖细胞（endothelial progenitor cells, EPCs）可促进损伤血管的再内皮化，抑制新生内膜的增生。充足的归巢是其功能发挥的前提，但临床及实验资料均显示EPCs移植的归巢和植入率非常低，严重影响其治疗效果。因此，如何提高EPCs的募集归巢已成为研究的焦点。整合素对EPCs的归巢及促血管修复功能具有重要的作用。Foxc2蛋白对于心血管系统的发育起重要的作用，而且可诱导内皮细胞整合素β3的表达，调控内皮粘附、迁移及促血管生成特性。Foxc2对EPCs生物功能的影响，目前未见报道。基于此，本课题通过过表达及沉默Foxc2，观察Foxc2对 EPCs整合素β3表达及迁移、粘附功能的影响；并将基因修饰的EPCs移植到动脉内膜损伤小鼠体内，研究Foxc2对EPCs归巢、促内皮修复及抑制新生内膜增生效应的影响，旨在为提高临床EPCs移植的疗效提供新思路。

内皮损伤、剥脱或功能障碍是动脉粥样硬化和血管成形术后再狭窄等心血管疾病发生进展的始动环节，促进损伤内皮的及早修复，对动脉粥样硬化的早期预防以及血管成形术后并发症的防治具有重要的意义。近来研究表明，动员或移植的（endothelial progenitor cells, EPCs）EPCs可直接分化为内皮细胞，和或通过分泌多种生长因子刺激成熟内皮增殖迁移，促进损伤血管的内皮修复。但临床及实验资料均显示EPCs移植的归巢和植入率非常低，严重影响其治疗效果。因此，如何提高EPCs的募集归巢已成为研究的焦点。整合素对EPCs的归巢及促血管修复功能具有重要的作用。Foxc2蛋白对于心血管系统的发育起重要的作用，而且可诱导内皮细胞整合素β3的表达，调控内皮粘附、迁移及促血管生成特性。Foxc2对EPCs生物功能的影响，目前未见报道。基于此，本课题欲通过过表达及沉默Foxc2，观察Foxc2对 EPCs整合素β3表达及迁移、粘附功能的影响；并将基因修饰的EPCs移植到动脉内膜损伤小鼠体内，观察Foxc2对EPCs归巢、促内皮修复及抑制新生内膜增生效应的影响。.本课题在小鼠骨髓EPCs培养及鉴定的基础上，体外EPCs过表达Foxc2，定量PCR及WB检测发现Foxc2过表达增加EPCs整合素β3mRNA及蛋白的表达；Transwell小室及粘附实验检测发现Foxc2过表达增加EPCs迁移及粘附功能；但整合素β3抗体封闭可减少Foxc2过表达增加EPCs的迁移及粘附效能。颈动脉损伤动物体内静脉注射EPCs，Foxc2过表达可增加EPCs的归巢、损伤血管的再内皮化及抑制新生内膜形成的作用；整合素β3抗体封闭可降低Foxc2过表达增加的EPCs归巢、损伤血管再内皮化及抑制新生内膜形成的作用。OX-LDL处理可降低EPCs整合素β3 mRNA及蛋白的表达及迁移、粘附功能。本课题初步研究结果提示，Foxc2通过上调EPCs整合素β3的表达，提高EPCs迁移、粘附、归巢及损伤血管内皮修复的作用，因此Foxc2转录因子是内皮祖细胞生物学功能及心血管修复作用中一个重要的调控靶点，为提高临床EPCs移植的治疗效果提供新的思路及实验依据。