Modulating Endothelialization of Cardiovascular Grafts

描述（由申请人提供）：血管旁路手术迫切需要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自体静脉管道旁路腿部动脉。在某种程度上，建立内皮化移植物的挑战是我们对特定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。已知肝素可调节生长反应，但由于肝素结构的异质性及其不同的相互作用，肝素的作用一直令人困惑和矛盾。我们已经发现，血管内皮生长因子（VEGF）和纤维连接蛋白（Fn）有一个独特的和专门的生物伙伴关系。Fn与VEGF的结合不同于其他基质蛋白，Fn显著增强VEGF介导的内皮细胞迁移和增殖。它们的同源受体α 5 β 1和VEGFR 2也协同作用。我们还证明了VEGF-Fn复合物独特地增强了内皮祖细胞（EPC）向内皮细胞系的分化。我们的目标是：1）阐明Fn促进VEGF活性的潜在机制，2）定义肝素调节VEGF-VEGFR 2结合的结构-活性关系，3）定义和开发重组纤连蛋白构建体和肝素寡糖，当与VEGF和EPC组合时，其将通过毛细血管的生长和EPC的分化增强多孔血管移植物的内皮化。使用重组Fn构建体，我们将确定Fn结构域是促进VEGF促有丝分裂作用的关键。使用结构上确定的合成寡糖，和新的表面等离子体共振技术，我们将确定最佳的大小和结构的肝素，促进VEGF结合其受体VEGFR 2。在一个与人类情况非常相似的外周动脉旁路移植动物模型中，我们将测试这些结构和细胞促进稳定内皮细胞生长的能力。

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.