Microfluidic Tissue Engineering of Small Airway Injuries

在涉及粘液分泌和小气道运动的疾病中，如慢性支气管炎， 囊性纤维化或哮喘，液体栓塞形成阻塞性桥梁，阻塞气道并破坏气体 交易所咳嗽时，这些桥移动，气道重新开放， 呼吸道上皮细胞的机械力。同样，在涉及气道和肺泡的情况下， 空间，如肺炎或充血性心力衰竭，或机械通气与低潮气量， 小气道周期性关闭和重新开放，这可能被认为是容易听到的爆裂声 用听诊器这些爆炸产生的爆炸性瞬态压力波的细胞水平效应 然而，尽管相关的可能性很大， 栓塞破裂产生大的应力，并且是肺损伤的主要原因。这项提案将进行调查， 实验和理论上，流体机械应力对气道上皮细胞的有害影响 在使用微工程气道重新打开气道期间。具体的假设是， 在气道重新打开期间，小气道系统中的液体堵塞物的破裂将产生大量流体 机械应力和损伤气道上皮细胞，即使是正常的亚致死量的液体， 机械应力在其它损伤如细菌或高氧介导的 炎症，扩大损伤区域和严重程度。这项建议的具体目标是： 1.气道上皮细胞体外培养仿生微流控系统的设计与制作 细胞在生理气液界面条件下。 2.具有生理传播速度和破裂频率的液体栓在血管内的产生 工程微流体小气道，并结合计算和实验评估， 产生的流体机械应力及其对细胞损伤的影响。 3.研究由液体栓塞传播/破裂组合引起的协同细胞损伤- 介导的流体机械应力和细菌感染或高氧介导的炎症。还有， 评估表面活性剂作为减少细胞损伤的对策的效果。

In diseases that involve mucus secretion and movement in the small airways, such as chronic bronchitis, cystic fibrosis or asthma, liquid plugs form occluding bridges that obstruct the airway and disrupt gas exchange. In response to cough, these bridges move and the airway is reopened, with the transmission of mechanical forces to airway epithelial cells. Similarly, in the setting that involve both the airway and alveolar space, such as pneumonia or congestive heart failure, or mechanical ventilation with low tidal volumes, there is cyclic closure and reopening of smaller airways, which may be recognized as crackle sounds heard easily with a stethoscope. The cellular-level effect of the explosive transient pressure waves created by these reopening events, however, has not previously been investigated despite the likelihood that the associated plug rupture produces large stresses and is a major cause of lung injury. This proposal will investigate, experimentally and theoretically, the detrimental effect of fluid mechanical stresses on airway epithelial cells during airway reopening using a micro-engineered airway. The specific hypothesis is that the movement and rupture of liquid plugs in the small airway system during airway reopening will generate large fluid mechanical stresses and damage airway epithelial cells, and that even normally sub-lethal amounts of fluid mechanical stress will become lethal in the presence of other insults such as bacteria or hyperoxia-mediated inflammation, expanding the region and severity of injury. The specific aims of this proposal are: 1. Design and fabrication of a biomimetic microfluidic system to perform in vitro culture of airway epithelial cells under physiological air-liquid interface conditions. 2. Generation of liquid plugs with physiological propagation velocities and rupture frequencies within the engineered microfluidic small airways, and combined computational and experimental assessment of the resulting fluid mechanical stresses and their effect on cell injury. 3. Investigate synergistic cellular damage caused by combination of liquid plug propagation/rupture- mediated fluid mechanical stresses and bacterial infection or hyperoxia-mediated inflammation. Also, evaluate the effect of surfactant as a countermeasure to reduce cellular injuries.