Aging and the Microvasculature

血管生成，即从先前存在的血管系统形成(萌芽)新的血管，随着年龄的增长而受损。这种损伤不利于伤口的愈合和缺血组织的血运重建。 尽管它在临床上很重要，但在衰老过程中，调控血管新生的细胞机制以及构成新形成血管的微血管内皮细胞和壁细胞却知之甚少。由于组织厚度以及间质和炎性细胞的存在，血管新生发芽的细节在体内很难观察到。此外，每一芽的尖端区域是研究的关键区域，在组织切片中很少发现。我们认为，体外培养的血管段是研究血管生成芽细节的最有效的手段。在这个模型中，血管节段从微循环丰富的组织(如脂肪)中分离出来，放置在三维胶原凝胶中，模拟体内的间质基质。这些节段充当“母体血管”，萌芽从这些血管中产生并被成像。 我们建议使用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发模型的能力。我们的假设是，相对于内皮细胞，老化的萌芽会表现出壁细胞数量的增加，细胞与细胞接触的形成被推迟。我们还假设基底膜的沉积将正常进行，但发芽尖端的基质周转不足。目标1将定义与增殖相关的细胞成分、形态、取向和迁移的影响。目的2确定AGE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。结果将定义关键字 在老年人中发现微血管生长不足的点，也将微血管萌芽模型发展成为研究一般血管生长的一个非常有用的工具。

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.