载脂蛋白A损伤小鼠骨髓源性EPCs血管发生能力及其机制

ApolipoproteinA Impairs Endothelial Progenitor Cell-mediated Vasculogenesis and Its Mechanism

改善血流、促进血管新生是缺血性外周血管疾病的重要治疗措施.由于载脂蛋白A(ApoA)与纤溶酶原(plasminogen,Plg)具有75%～98%的结构同源性,因此,ApoA也可能通过类似Plg的方式抑制内皮祖细胞(endothelial progenitor cells,EPCs)增殖、黏附及迁移而影响血管发生的能力.本文研究ApoA对EPCs血管发生的影响及机制.为了编码人ApoA全长cDNA序列的pSG-5表达载体,转染COS-7细胞株后进行培养,收集培养液,免疫亲和层析法分离纯化ApoA蛋白;从转ApoA基因小鼠、野生型对照鼠及正常对照鼠骨髓分离培养EPCs,经ApoA处理后移植下肢缺血实验小鼠,于移植后第3、7、14天后观察ApoA对EPCs黏附、迁移及血管发生能力的影响.研究发现,ApoA能显著降低EPCs的黏附、迁移能力,Matrigel胶上,EPCs血管腔样结构严重破坏,体内实验揭示,EPCs归巢至ApoA转基因小鼠缺血组织血管周围的数量及毛细血管数量显著减少.结果表明,ApoA能损伤EPCs的黏附、迁移及归巢,最终损伤EPCs的血管发生能力.

Improvement of blood flow and promotion of neovascularization are important therapeutic measures for ischemic peripheral vascular diseases. Since apolipoproteinA（ApoA） is a glycoprotein with repetitive kringle domains exhibiting 75% to 98% structural homology with plasminogen（Plg）, ApoA may also have a negative effect on endothelial progenitor cell （EPC）-induced vasculogenesis through Plg-like inhibitory effects on EPC proliferation, adhesion, migration and vasculogenesis. To evaluate the effect of ApoA on EPCs-induced vasculogenesis. ApoA was stably expressed and prepared from COS-7 cell line which were transfected with the expression plasmids pSG-5 encoding human ApoA cDNA, then purified by immunoaffinity chromatography; EPCs were isolated from the bone marrow of ApoA transgenic mice, wild-type litter mates and normal mice. These cells were cultured without or with ApoA before transplantation. Hindlimb ischemia models were surgically induced in mice, which then received an intravenously injection of 3 xl05 EPCs. At 3, 7 and 14 days post EPC transplantation, the adhesion, migration abilities and capillary density in calf muscles were assessed. Results indicate that ApoA significantly reduced the adhesion and migration abilities of EPCs. Furthermore, the tubule-like formation of EPCs on Matrigel gels was damaged. In vivo experiments showed the number of EPCs home to ischemic peripheral vascular, and the number of capillary vessels decreased significantly in ApoA transgenic mice. This study demonstrated that ApoA could attenuate the adhesion, migration, and homing abilities of EPCs and could impair the vasculogenesis ability of EPCs.