Cytokine Regulation of Early Events in Blood Vessel Form

描述（由申请方提供）：血管发生是中胚层血管的从头形成。血管发生过程的基本步骤是由未分化的中胚层产生成血管细胞，并将成血管细胞聚结和转化为内皮细胞（EC）。此外，我们的研究揭示了该过程的后续步骤，涉及小血管融合形成大血管和血管窦。这个过程被称为血管融合，是由于实验发现的，其中VEGF水平升高显示出导致不受控制的融合，过度融合。VEGF诱导的过度融合不仅在多个物种的胚胎中有描述，而且在成年新生血管过程中也很重要。事实上，不受控制的融合活性现在成为VEGF设想的许多治疗用途的障碍。了解控制血管融合的机制一直是我们研究的重点。结果发现，VEGF/VEGF受体在融合和过度融合中起关键作用，且内皮细胞密度与特定血管类型之间存在相关性。基于这些和其他研究结果，我们得出了这样的假设，即EC数量/密度的调节是正常血管融合和过度融合的病理过程的基础。影响EC数量/密度的主要方式包括控制有丝分裂、凋亡和/或从中胚层募集EC祖细胞。本申请中概述的实验将确定VEGF-A（VEGF 165/VEGFt 21）和PLGF信号传导通过VEGF受体（Flkl、Fltl和神经纤毛蛋白1和2）影响血管形态发生并用于调节EC数量/密度的形态学后果和机制。关于招募祖细胞到血管发生的位点，我们也将扩展我们的初步研究结果，表明循环胚胎干细胞有助于血管发生和血管融合。拟议的研究计划的一个主要优势是使用我们完善的体内禽类试验和一个强大的新的体外小鼠血管发生模型，该模型概括了体内血管发生的突出方面。拟议的研究预计将有助于更好地了解血管发生，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.