Modulating Endothelialization of Cardiovascular Grafts

描述(申请人提供)：血管搭桥手术急需一种耐用的生物假体血管移植物。对于外周血管手术，基本上没有可行的替代方法来替代自体静脉管道来搭桥腿部动脉。在某种程度上，建立内皮化移植物的挑战在于，我们对特定的生长因子和基质蛋白如何相互作用并调节细胞反应的理解存在差距。众所周知，肝素可以调节生长反应，但由于肝素结构的异质性和不同的相互作用，肝素的作用一直令人困惑和矛盾。我们发现血管内皮生长因子(VEGF)和纤维连接蛋白(FN)具有独特和独特的生物伙伴关系。FN与血管内皮生长因子的结合不同于其他基质蛋白，FN能显著促进血管内皮生长因子介导的内皮细胞迁移和增殖。它们的同源受体Alpha5beta1和VEGFR2也发挥协同作用。我们还证明了血管内皮生长因子-纤维连接蛋白复合体具有独特的促进内皮祖细胞(EPC)向内皮线分化的作用。我们的目标是：1)阐明FN促进血管内皮生长因子活性的机制，2)明确肝素调节VEGF-VEGFR2结合的构效关系，3)定义和开发重组纤维连接蛋白和肝素低聚糖，当它们与血管内皮生长因子和内皮祖细胞结合时，将通过毛细血管生长和内皮祖细胞分化来促进多孔血管移植物的内皮化。利用重组的FN结构，我们将确定FN结构域是促进血管内皮生长因子有丝分裂作用的关键。使用结构定义的合成低聚糖，以及新的表面等离子共振技术，我们将确定促进VEGF与其受体VEGFR2结合的肝素的最佳大小和结构。在外周动脉旁路移植的动物模型中，我们将测试这些结构和细胞是否有能力促进稳定的内皮衬里的生长。

DESCRIPTION (provided by applicant): A durable bioprosthetic vascular graft is badly needed for vascular bypass surgery. For peripheral vascular surgery, there is essentially no viable alternative to an autogenous venous conduit to bypass leg arteries. In part, the challenges to establishing an endothelialized graft have been gaps in our understanding of how specific growth factors and matrix proteins interact with each other and modulate cellular responses. Heparins are known to modulate growth responses, but heparin's effects have been confusing and contradictory, due to the heterogeneity of heparin's structure and its diverse interactions. We have discovered that vascular endothelial growth factor (VEGF) and fibronectin (Fn) have a unique and dedicated biologic partnership. Fn binds VEGF like no other matrix protein, and Fn significantly enhances the endothelial migration and proliferation mediated by VEGF. Their cognate receptors, alpha5beta1 and VEGFR2 also work in synergy. We have also demonstrated that VEGF-Fn complexes uniquely enhance the differentiation of endothelial progenitor cells (EPC) into the endothelial line. Our goals are: 1) Elucidate the mechanisms underlying Fn promotion of VEGF activity, 2) Define the structure-activity relations of heparin's modulation of VEGF-VEGFR2 binding, 3) Define and develop recombinant fibronectin constructs and heparin oligosaccharides that when combined with VEGF and EPC will enhance endothelialization of a porous vascular graft, by capillary in growth and the differentiation of EPC. Using recombinant Fn constructs, we will identify the Fn domains that are key to promoting VEGF mitogenic effects. Using structurally defined synthetic oligosaccharides, and novel surface plasmon resonance technology we will identify the optimal size and structure of heparin that promotes VEGF binding to its receptor VEGFR2. In an animal model of peripheral artery bypass grafting that closely resembles the human condition, we will test these constructs and cells for their ability to promote the growth of a stable endothelial lining.