Induction of cardio-vascular progenitor cells and blood vessel formation by ES cell differentiation.

脊椎动物胚胎发生过程中，初级血管丛和随后由大小血管组成的血管树的形成机制在很大程度上是未知的。小鼠ES细胞的体外分化系统是一种将复杂的血管发育过程分解为可以真实的实时监测的细胞事件的手段。我们已经开发了一种培养系统，其中内皮细胞，心肌细胞和平滑肌细胞分化从一个单一的中胚层前体细胞来源于ES细胞。该培养系统在中胚层细胞群中鉴定出三能心血管祖细胞。ES细胞来源的内皮细胞集落在基质细胞层上产生，已被用作体外模型来检查个体内皮细胞对各种血管生成刺激物（如VEGF）的反应。显示VEGF信号诱导内皮细胞的伸长和分散。我们发现了一个叉头型的transri 关于我们 本研究通过构建表达VE-cadherin基因启动子/增强子调控下的VE-cadherin-VENUS或claudin 5-VENUS的ES细胞克隆，探讨了foxo 1基因缺陷小鼠胚胎血管生成异常的机制。ES细胞衍生的内皮细胞集落的延时分析显示内皮细胞的活跃运动。尽管内皮细胞具有高运动性，但维持了基于VE-钙粘蛋白的粘附连接和基于紧密连接蛋白5的紧密连接的完整性。在运动的内皮细胞的前缘确定了细胞连接的动态重塑过程。利用VE-cadherin启动子-Cre转基因小鼠进行的命运追踪分析表明，心肌缺血激活了既存血管细胞和骨髓细胞中VE-cadherin启动子，这些细胞参与了新生血管的形成。我们还表明，过度表达的转录因子c-Myb增加了造血前体的频率在内皮细胞群，这提供了一个线索，造血内皮细胞如何致力于确定造血细胞谱系在小鼠胚胎发生。少

The mechanism by which primary plexus and subsequent vascular tree which consists of large and small vessels form in the process of vertebrate embryogenesis is largely unknown. In vitro differentiation system of murine ES cells serves as a means to break down the complicated processes of vascular development into cellular events which can be monitored in real time. We have developed a culture system in which endothelial cells, cardiomyocytes and smooth muscle cells differentiate from a single mesodermal precursor cell derived from ES cells. This culture system identified tri-potent cardio-vascular progenitor cells in the mesodermal cell population.ES cell-derived endothelial cell colonies generated on stromal cell layer have been used as an in vitro model to examine the behavior of individual endothelial cells in response to various angiogenic stimuli such as VEGF. The VEGF signal was shown to induce elongation and dispersion of endothelial cells. We identified a forkhead-type transcri … More ption factor Foxo1 as a regulatory molecule in the elongation reaction of endothelial cells, which might account for the severe abnormality of angiogenesis found in foxo1-deficient mouse embryos.We produced ES cell clones which express VE-cadherin-VENUS or claudin 5-VENUS under the regulation of VE-cadherin gene promoter/enhancer. Time-lapse analysis of ES cell-derived endothelial cell colonies revealed an active movement of endothelial cells. Integrity of the VE-cadherin-based adherens junction and the claudin 5-based tight junctin was maintained despite the high motility of endothelial cells. A dynamic remodeling process of cell junctions was identified at the leading edges of moving endothelial cells. Modulation of endothelial cell motility might be an important process which drives the vascular development at the cell level.Fate tracing analyses by using VE-cadherin promoter-Cre transgenic mice showed that cardiac ischemia activate VE-cadherin promoter in both pre-existing vascular cells and bone marrow cells involved in neovascularization. We also demonstrated that over-expression of a transcription factor c-Myb increases the frequency of hemogenic precursors in the endothelial cell population, which provides a clue to how hemogenic endothelial cells commit to definitive hematopoietic cell lineages during the mouse embryogenesis. Less