Cytokine Regulation of Early Events in Blood Vessel Form

描述(申请人提供)：血管生成是指中胚层血管的从头形成。血管生成的基本步骤是从未分化的中胚层生成血管母细胞，以及血管母细胞融合和转化为内皮细胞(ECs)。此外，我们的研究还揭示了这一过程的后续步骤，即小血管融合形成大血管和血管窦。这一过程被称为血管融合，这是实验的结果，在实验中，高水平的血管内皮生长因子被证明会导致不受控制的融合，过度融合。血管内皮生长因子诱导的超融合不仅在多种物种的胚胎中被描述，而且在成人的新生血管过程中也被重要地描述。事实上，不受控制的融合活动现在是血管内皮生长因子预期的众多治疗用途的障碍。了解血管融合的控制机制(S)一直是我们研究的重点。结果发现，血管内皮生长因子/血管内皮生长因子受体在血管融合和超融合中起关键作用，血管内皮细胞密度与特定的血管形态之间存在相关性。基于这些和其他发现，我们提出了一个假设，即EC数量/密度的调节是正常的血管融合和过度融合的病理过程的基础。影响EC数量/密度的主要途径包括控制有丝分裂、凋亡和/或中胚层EC前体细胞的募集。本申请中概述的实验将确定血管内皮生长因子-A(VEGF165/VEGFt21)和PLGF信号通过血管内皮生长因子受体(Flk1、Flt1和Neuropilin 1和2)影响血管形态发生和调节EC数量/密度的形态学后果和机制。关于祖细胞向血管生成部位的募集，我们还将扩展我们的初步发现，即循环中的胚胎干细胞有助于血管生成和血管融合。拟议研究计划的一个主要优点是使用了我们成熟的体内禽类实验和一种强大的体外小鼠血管生成模型，该模型概括了体内血管生成的显著方面。这项拟议的研究有望有助于更好地了解血管生成、血管融合和过度融合，并为针对各种疾病的新生血管成分的策略提供新的视角。

DESCRIPTION (provided by applicant): Vasculogenesis is the de novo formation of blood vessels from mesoderm. Basic steps in the process of vasculogenesis are the generation of angioblasts from undifferentiated mesoderm and the coalescence and transformation of angioblasts into endothelial cells (ECs). In addition, our studies have revealed a subsequent step in the process that involves the fusion of small vessels to form large vessels and vascular sinuses. This process, termed vascular fusion, was discovered as a result of experimentation in which elevated levels of VEGF were shown to lead to uncontrolled fusion, hyperfusion. VEGF-induced hyperfusion has not only been described in embryos of multiple species, but importantly in adult neovascular processes. Indeed, uncontrolled fusion activity now stands as an impediment to the numerous therapeutic uses envisioned for VEGF. Understanding the mechanism(s) by which vascular fusion is controlled has been a focus of our research. As a result we have found that VEGF/VEGF receptor is critical to fusion and hyperfusion and that a correlative relationship exists between the density of ECs and specific vascular patterns. Based on these and other findings we have derived the hypothesis that regulation of EC numbers/density is fundamental to normal vascular fusion and the pathological process of hyperfusion. Major ways to influence EC numbers/density include control of mitosis, apoptosis and/or recruitment of EC progenitor cells from mesoderm. Experimentation outlined in this application will determine the morphological consequences of and the mechanisms by which VEGF-A (VEGF165/VEGFt21) and PLGF signaling via the VEGF receptors (Flkl, Fltl and Neuropilin 1 & 2) impact vascular morphogenesis and act to regulate EC numbers/density. With respect to recruitment of progenitor cells to sites of vasculogenesis, we will also extend on our preliminary findings indicating that circulating embryonic stem cells contribute to vasculogenesis and vascular fusion. A major strength of the proposed research plan is the use of both our well-established in vivo avian assay and a powerful new in vitro murine model of vasculogenesis that recapitulates salient aspects of in vivo vasculogenesis. The proposed research is expected to contribute to a greater understanding of vasculogenesis, vascular fusion, and hyperfusion and offer new perspectives for strategies that target the neovascular component of various diseases.