VEGFR1+/CXCR4+干细胞归巢在抑制静脉桥再狭窄中的作用及其机理研究

Saphenous vein is the most widely used as a graft in coronary artery bypass grafting (CABG).However, vein graft restenosis owing mainly to early thrombosis and intimal hyperplasia in vascular remodeling always happens after the surgery. Our previous studies and reports suggest that VEGFR1+/CXCR4+ stem cells can express endothelial nitric oxide synthase (eNOS) which can produce nitric oxide (NO). NO as an effective factor inhibit activation of platelet and leukocyte. Activated platelet and leukocyte were known as important roles in thrombosis and vascular remodeling. As a result, VEGFR1+/CXCR4+ stem cells can reduce thrombosis and vascular remodeling. This study aims to reveal whether homing VEGFR1+/CXCR4+ stem cells can suppress vein graft restenosis by observing the relationship between VEGFR1+/CXCR4+ stem cells and restenosis of vein graft. We also study in what role dose homing VEGFR1+/CXCR4+ stem cells play in inhibition of early thrombosis and intimal hyperplasia and even mitigation of vein graft restenosis based on a rat model of vein grafting (femoral vein anastomosis end to end to the common carotid artery). We tried to find whether VEGFR1+/CXCR4+ stem cells can suppress activation of platelet and leukocyte so that thrombosis and intimal hyperplasia can be inhibited further by blocking eNOS artificially in vivo and in vitro. We set to research the effects and mechanisms of inhibition of vein graft restenosis by homing VEGFR1+/CXCR4+ stem cells. We hope our results can provide a primary theoretical and experimental evidence for development of target drug and treatment for vein graft restenosis after CABG.

大隐静脉是冠脉搭桥术应用最广泛的桥血管，早期血栓形成和以内膜增生为主的血管重构是静脉桥再狭窄的主要原因。前期研究和文献显示，VEGFR1+/CXCR4+干细胞可表达eNOS，并可能通过生成NO抑制血小板、白细胞活化进而抑制血栓形成和血管重构。本研究拟通过观察VEGFR1+/CXCR4+干细胞与静脉桥血管重构的关系，研究其动员、归巢能否减轻静脉桥再狭窄。基于大鼠静脉-动脉吻合模型，研究促进VEGFR1+/CXCR4+干细胞归巢在抑制早期血栓形成和内膜增生进而减轻静脉桥再狭窄中的作用；利用在体实验和离体细胞培养模型，通过阻断eNOS，研究VEGFR1+/CXCR4+干细胞是否通过NO生成而抑制血小板、白细胞激活，从而抑制血栓形成和内膜增生。本课题在前期基础上开展VEGFR1+/CXCR4+干细胞归巢在抑制静脉桥再狭窄中的作用和机制研究，为开发特异性药物或治疗手段提供初步的理论基础和实验依据。

大隐静脉是冠脉旁路移植术应用最广泛的桥血管，早期血栓形成和以内膜增生为主的血管重构是静脉桥再狭窄的主要原因。我们发现胎盘生长因子（PlGF，PLacental growth factor）有减轻静脉桥内膜增生的作用，但机制不详。我们推测可期与PlGF保护内皮细胞存活；上调eNOS生成NO而抑制血小板、白细胞的活化和粘附，从而减轻静脉桥再狭窄；诱导VEGFR1+/CXCR4+干细胞归巢等作用密切相关。为此本项目暂开了以下研究：1）通过构建大鼠右颈外静脉-颈总动脉吻合模型，应用PlGF水凝胶外模方式给药，评价了PlGF水凝胶血管外模给药的有效性。通过病理组织技术，发现PlGF在静脉移植早期能促进内皮细胞存活，减少内皮细胞剥脱、减轻移植静脉内膜增厚的作用，这一作用主要机制为eNOS表达上调，增加移植早期血清和静脉桥NO的含量，促进静脉桥更多微血管新生等。2）通过构建内皮细胞损伤模型，明确了缺氧时间培养与内皮细胞损伤机制的关系，应用含PlGF的培养基对缺氧损伤细胞的干预，首次发现PlGF能够恢复缺氧损伤后内皮细胞的增殖、存活、迁移及成管能力等生物学功能。3）通过TNF-α诱导内皮细胞发生炎症反应，发现PlGF可下调内皮细胞（CAM1、VCAM1）、内皮素（ET1）及血管性血友病因子（VWF）在mRNA及蛋白不同水平的表达；通过致炎内皮细胞与白细胞或血小板的共同培养，发现PlGF能降低PF4、PAF上清液浓度，从而减轻白细胞和血小板活性。通过细胞通路研究，发现PlGF可通过PI3K-AKT通路上调eNOS表达，发挥修复内皮细胞的修复功能。.