Exogenous Fluid Forces and Branching of the Mammalian Lung

项目总结 哺乳动物肺的呼吸道上皮在外源性液体力的作用下发育。 胎儿呼吸运动和周围平滑肌的蠕动收缩。产品中的缺陷 胸腔的机械环境，包括先天性横隔疝或 羊水过少，出生后可导致肺发育不全和呼吸衰竭。尽管有几个主要的 包括成纤维细胞生长因子10(FGF10)在内的生化信号已在呼吸道的控制中被确认 分枝形态发生，机械扰动引起的信号缺陷尚不清楚。在这里，我们 建议使用微流体方法复制胎儿胸腔的机械环境，并 探讨液体压力、体积和流量对胚胎小鼠肺外植体发育的影响。我们 将把这些微流控方法与从转基因报告移植的肺的时间流逝成像结合起来 老鼠，呼吸道内流体流动的粒子成像测速分析，以及分子分析 机械转导信号在FGF10信号轴调节中的作用。在具体目标1中，我们将 确定静态跨壁压力和腔内液体容量如何调节呼吸道上皮的分支， 间充质的发育，FGF10及其已知调控因子的表达。我们还将量化 上皮、间充质和内皮细胞的增殖、凋亡和细胞形态变化的机械调节 间皮细胞。在具体目标2中，我们将模拟胎儿呼吸运动引起的压力变化。 并量化这些动态变化对形态发生、基因表达和液体运输的影响 在发育中的肺里。这项工作将隔离压力、体积和流量的影响，并精确地定义 每种细胞对呼吸道及其周围间充质的形态发生有何作用 和分子水平。我们期待这一模式系统将为识别 治疗压力引起的疾病，如胎儿肺发育不全。

PROJECT SUMMARY The airway epithelium of the mammalian lung develops in the presence of exogenous fluid forces exerted from fetal breathing movements and peristaltic contraction of the surrounding smooth muscle. Defects in the mechanical environment of the thoracic cavity, including those due to congenital diaphragmatic hernia or oligohydramnios, can lead to pulmonary hypoplasia and respiratory failure after birth. Although several major biochemical signals, including fibroblast growth factor 10 (FGF10), have been identified in the control of airway branching morphogenesis, the signaling defects resulting from mechanical perturbations are unclear. Here, we propose to use microfluidic approaches to replicate the mechanical environment of the fetal chest cavity and explore effects from fluid pressure, volume, and flow on development of embryonic mouse lung explants. We will combine these microfluidic approaches with timelapse imaging of lungs explanted from transgenic reporter mice, particle imaging velocimetry analysis of the fluid flow within the airways, and molecular analysis of mechanotransductive signaling in the regulation of the FGF10 signaling axis. In Specific Aim 1, we will determine how static transmural pressure and luminal fluid volume regulate branching of the airway epithelium, development of the mesenchyme, and expression of FGF10 and its known regulators. We will also quantify mechanical regulation of proliferation, apoptosis, and cell shape changes in the epithelium, mesenchyme, and mesothelium. In Specific Aim 2, we will mimic the pressure changes that result from fetal breathing movements and quantify the effects of these dynamic changes on morphogenesis, gene expression, and fluid transport within the developing lung. This work will isolate the effects of pressure, volume, and flow and define precisely how each contributes to morphogenesis of the airways and their surrounding mesenchyme at both the cellular and molecular levels. We expect that this model system will open new avenues of investigation for identifying medical treatments to combat pressure-induced diseases such as fetal pulmonary hypoplasia.