Aging and the Microvasculature

血管生成，即从预先存在的血管系统形成（发芽）新血管，在衰老中受损。这种损伤对伤口的愈合和缺血组织的再血管化是有害的。 尽管它的临床重要性，调节血管生成发芽的细胞机制，以及微血管内皮细胞（EC）和壁细胞，包括新形成的血管，在老化中知之甚少。由于组织厚度以及基质细胞和炎性细胞的存在，在体内难以观察到血管生成发芽的细节。此外，每个芽的尖端区域，这是一个关键的调查领域，很少发现在组织切片。我们建议离体培养的血管段是研究血管新生芽细节的最有效手段。在该模型中，从具有丰富微循环的组织（例如，脂肪）并置于模拟体内间质基质的三维胶原凝胶中。这些节段用作“母血管”，从中生成芽并对其成像。 我们建议使用来自年轻和老年小鼠的微血管，结合新的培养方法和现代图像分析，来改进和扩展微血管萌芽模型的能力。我们的假设是，老化的芽将显示壁细胞的数量增加，相对于内皮细胞，细胞与细胞接触的形成被延迟。我们还假设，基膜的沉积将正常进行，但会有不足的基质周转在芽尖。目的1将定义细胞成分、其形态、方向以及相对于增殖的迁移影响。目的2将确定年龄对细胞-细胞接触形成、基底膜蛋白沉积和基质降解金属蛋白酶表达/活性的影响。结果将定义密钥 点的缺陷微血管生长在老年人，也发展了微血管萌芽模型成为一个非常有用的工具，研究血管生长的一般。

Angiogenesis, the formation (sprouting) of new blood vessels from pre-existing vasculature, is impaired in aging. This impairment is detrimental to the healing of wounds and revascularization of ischemic tissues. Inspite of its clinical importance, the cellular mechanisms that regulate angiogenic sprouting, and the microvascular endothelial cells (ECs) and mural cells that comprise newly formed vessels, are poorly understood in aging. The details of angiogenic sprouting are difficult to observe in vivo due to tissue thickness and the presence of stromal and inflammatory cells. Moreover, the tip region of each sprout, which is a critical area of investigation, is rarely found in tissue sections. We propose that vascular segments cultured ex vivo are the most effective means to study the details of angiogenic sprouts. In this model, vascular segments are isolated from tissues with an abundant microcirculation (e.g., adipose) and placed in 3-dimensional collagen gels that simulate interstitial matrix in vivo. The segments serve as "parent vessels" from which sprouts are generated and imaged. We propose to use microvessels from young and aged mice, in conjunction with novel culture methods and modern image analysis, to refine and extend the capabilities of the microvascular sprout model. Our hypothesis is that aged sprouts will show an increase in the number of mural cells, relative to ECs, and that the formation of cell-cell contacts is delayed. We also postulate that deposition of basement membrane will proceed normally, but there will be deficient matrix turnover at sprout tips. Aim 1 will define the cellular components, their morphology, orientation, and the influence of migration, relative to proliferation. Aim 2 will determine the influence of age on formation of cell-cell contacts, the deposition of basement membrane proteins, and the expression/activity of matrix degrading metalloproteinases. The results will define the key points of deficient microvascular growth in the aged and also develop the microvessel sprout model into a highly useful tool for studies of vascular growth in general.