EXTRACELLULAR MATRIX GUIDANCE OF CAPILLARY SPROUTING

众所周知，血管生成是许多肿瘤的关键组成部分， 正常和病理状态，包括肌肉对运动的适应， 心肌对缺血的适应、肿瘤的发展和伤口愈合。 通常，新的血管通过从预先存在的毛细血管发芽形成， 微血管网中的小静脉。已显示 缺乏VEGF受体的周细胞样非内皮细胞引导毛细血管 从大鼠结缔组织中预先存在的微血管中发芽。这周细胞 引导细胞在体内在微纤维基质上迁移并产生第二个 临时基质可以是血管内皮细胞的支架， 芽的近端部分。这项建议包括三个具体目标 旨在更好地阐明细胞周前导细胞的作用， 微纤维网络和由周细胞产生的次级基质 引导细胞在毛细血管发芽中发挥作用。第一个具体目标是更好地 表征所选细胞外基质蛋白的空间表达， 毛细血管芽中的整合素、生长因子和生长因子受体 和周围组织区域的肠系膜网络进行自发性 血管生成和响应于伤口愈合、炎症的血管生成，以及 缺氧第二个具体目标将利用创新的体内方法， 分析细胞周引导细胞和内皮细胞在细胞膜上的迁移， 基础矩阵，以应对选定的增长因素的应用 (VEGF bFGF、PDGF-BB、TGF β）。在这里，直接观察矩阵引导细胞 迁移或天然细胞外基质将在体内进行，从而 鉴定哪些生长因子能够作为化学引诱物 在基质引导的毛细血管发芽期间。第三个具体目标是 研究破坏选定的ECM-整合素相互作用的影响， 对毛细芽的组成和结构、微血管的发育和 密度和网络模式。该项目的长期目标是 了解周细胞样细胞之间必须发生的分子相互作用， 领导细胞，细胞外基质，和内皮细胞产生 毛细血管发芽，导致功能性微血管的形成 网络通过更好地理解细胞和分子信号， 对于这一重要过程至关重要，我们最终可能能够：1）发现 更好的介入抗血管生成治疗的靶点，2找到更好的 用于刺激缺血组织中血管生成的靶标，和3）组织 工程化细胞外基质支持形成 体内功能性微血管网络。

it is well known that angiogenesis is a critical component of many normal and pathological conditions, including muscle adaptation to exercise, myocardial adaptation to ischemia, tumor development, and wound healing. Typically, new blood vessels form by sprouting from pre-existing capillaries or small venules in the microvascular network. It has been shown that a periocyte-like, non-endothelial cell lacking VEGF receptors guides capillary sprouts from pre-existing microvessels in rat connective tissue. This pericytic guide cell migrates on a microfibril matrix in vivo and produces a second provisional matrix that may be a scaffolding for endothelial cells in the proximal portion of the sprout. This proposal consists of three specific aims that are designed to better elucidate the role that the pericytic leader cell, the microfibril network, and the secondary matrix produced by the pericytic guide cell play in capillary sprouting. The first specific aim is to better characterize the spatial expression of selected extracellular matrix proteins, integrins, growth factors, and growth factor receptors in the capillary sprout and surrounding tissue region in mesenteric networks undergoing spontaneous angiogenesis and angiogenesis in response to wound healing, inflammation, and hypoxia. The second specific aim will utilize an innovative in vivo approach to analyzing the migration of pericytic guide cells and endothelial cells on the underlying matrix in response to the application of selected growth factors (VEGF, bFGF, PDGF-BB, TGFbeta). Here, direct observations of matrix guided cell migration or native extracellular matrix will be made in vivo, thereby identifying which growth factors are capable of acting as chemoattractants during matrix guided capillary sprouting. 'The third specific aim is to investigate the impact that disrupting selected ECM-integrin interactions has on capillary sprout composition and structure, microvascular development and density and network patterning. The long term goal of this project is to understand the molecular interactions that must occur betweer the pericyte-like leader cells, the extracellular matrix, and the endothelial cells to produce capillary sprouting that leads to the formation of a functional microvascular network. By better understanding the cells and molecular signals that are essential for this essential process, we may eventually be able to, 1) find better targets for interventional anti-angiogenesis therapy, 2 find better targets for stimulating angiogenesis in ischemic tissues, and 3) tissue engineer extracellular matrix substrates the support the formation of functional microvascular networks in vivo.