Exogenous Fluid Forces and Branching of the Mammalian Lung

项目概要 哺乳动物肺部的气道上皮在外源流体力的存在下发育 胎儿的呼吸运动和周围平滑肌的蠕动收缩。缺陷在 胸腔的机械环境，包括由于先天性膈疝或 羊水过少，可导致出生后肺发育不全和呼吸衰竭。虽然几个主要 已确定生化信号，包括成纤维细胞生长因子 10 (FGF10)，可控制气道 分支形态发生中，机械扰动导致的信号传导缺陷尚不清楚。在这里，我们 提议使用微流体方法来复制胎儿胸腔的机械环境和 探索流体压力、体积和流量对胚胎小鼠肺外植体发育的影响。我们 将把这些微流体方法与从转基因报告基因中取出的肺部的延时成像相结合 小鼠，气道内流体流动的粒子成像测速分析，以及分子分析 FGF10 信号轴调节中的机械传导信号。在具体目标 1 中，我们将 确定静态跨壁压和管腔液体量如何调节气道上皮的分支， 间充质的发育以及 FGF10 及其已知调节因子的表达。我们也会量化 上皮、间充质和细胞增殖、凋亡和细胞形状变化的机械调节 间皮。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 在发育中的肺内。这项工作将隔离压力、体积和流量的影响，并精确定义 每个细胞如何促进气道及其周围间质的形态发生 和分子水平。我们期望该模型系统将为识别问题开辟新的调查途径 对抗压力引起的疾病（如胎儿肺发育不全）的药物治疗。

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.