Mechanical Control of Cell Proliferation and Branching Morphogenesis in the Embryonic Lung

项目总结/摘要 在胚胎肺中，支气管树是由一个称为分支形态发生的过程塑造的。缺陷 可引起各种先天性畸形，如肺发育不全， 由于肺生长减少而损害呼吸功能。这些缺陷中有几个是由 胎儿肺的机械环境的变化，但仍不清楚组织中的物理线索如何影响胎儿肺的机械环境。 微环境指导支气管树的形成。分支的动态定量研究 需要形态发生来阐明肺发育过程中机械力的调节作用。我们 假设气道分支是由机械反馈机制驱动的，其中模式 机械应力的作用调节上皮细胞增殖的模式，上皮细胞增殖塑造了发育中的气道。 为了验证这一假设，我们将使用新的实验平台，使我们能够控制和量化 胚胎气道上皮内的机械应力。我们最近开发了一种新颖的三维 (3D)用于培养的胚胎器官外植体的牵引力显微镜（TFM）测定，以及微培养物 该系统将受控的体液压力应用于完整的胚胎小鼠肺。这些技术将结合 细胞增殖和成纤维细胞生长因子（FGF）信号传导的动态研究，以及一种新的 气道分支形态发生的计算模型，以确定物理线索如何调节生长 以及胚胎肺的重塑在目标1中，我们将确定机械应力如何调节 在分离的气道上皮外植体中增殖。然后，在目标2中，我们将使用全肺外植体培养物， 揭示机械力如何与FGF相互作用，以指导正常和发育不良的分支 表型实现这些目标将有助于确定新的疾病治疗靶点，如先天性 疝，其中气道分支形态发生和肺生长严重受损。这些 结果也将有助于指导肺组织工程师在他们的努力，以概括方面的胚胎 在实验室中开发以构建工程化肺组织。

PROJECT SUMMARY/ABSTRACT In the embryonic lung, the bronchial tree is sculpted by a process known as branching morphogenesis. Defects in branching can cause a variety of congenital malformations, such as pulmonary hypoplasia, which compromises respiratory function due to decreased lung growth. Several of these defects are caused by changes in the mechanical environment of the fetal lung, but it remains unclear how physical cues in the tissue microenvironment direct the formation of the bronchial tree. Dynamic, quantitative studies of branching morphogenesis are needed to unravel the regulatory role of mechanical forces during lung development. We hypothesize that airway branching is driven by a mechanical feedback mechanism, in which patterns of mechanical stress regulate the patterns of epithelial proliferation that sculpt the developing airways. To test this hypothesis, we will use novel experimental platforms that allow us to control and quantify the mechanical stresses within the embryonic airway epithelium. We recently developed a novel three-dimensional (3D) traction force microscopy (TFM) assay for cultured embryonic organ explants, as well as a microfluidic system to apply controlled fluid pressures to intact embryonic mouse lungs. These techniques will be combined with dynamic studies of cell proliferation and fibroblast growth factor (FGF) signaling, as well as a novel computational model of airway branching morphogenesis, to determine how physical cues regulate the growth and remodeling of the embryonic lung. In Aim 1, we will determine how mechanical stress regulates patterns of proliferation in isolated airway epithelial explants. Then, in Aim 2, we will use whole lung explant culture to uncover how mechanical forces interact with FGFs to direct both normal and hypoplastic branching phenotypes. Achieving these aims will help identify new therapeutic targets for diseases, such as congenital diaphragmatic hernia, where airway branching morphogenesis and lung growth are severely impaired. These results will also help guide pulmonary tissue engineers in their efforts to recapitulate aspects of embryonic development in the laboratory to construct engineered lung tissue.