Microfluidic Tissue Engineering of Small Airway Injuries

描述（由申请人提供）：在涉及小气道粘液分泌和运动的疾病中，如慢性支气管炎、囊性纤维化或哮喘，液体塞形成闭塞的桥，阻塞气道并破坏气体交换。作为对咳嗽的反应，这些桥移动，气道重新开放，机械力传递给气道上皮细胞。同样，在涉及气道和肺泡空间的情况下，如肺炎或充血性心力衰竭，或潮气量低的机械通气，存在较小气道的周期性关闭和重新打开，听诊器可识别为容易听到的爆裂声。然而，尽管相关的塞子破裂可能会产生巨大的应力，并且是肺损伤的主要原因，但这些重新打开事件所产生的爆炸性瞬态压力波的细胞水平效应尚未被研究过。本研究将从实验和理论上探讨微工程气道重开过程中流体机械应力对气道上皮细胞的不利影响。具体的假设是，在气道重开过程中，小气道系统中液体塞的运动和破裂会产生巨大的流体机械应力并损伤气道上皮细胞，并且在存在其他损伤（如细菌或高氧介导的炎症）的情况下，即使通常是亚致死量的流体机械应力也会变得致命，从而扩大损伤的区域和严重程度。本建议的具体目的是：1。仿生微流体系统的设计与制造，用于在生理气液界面条件下体外培养气道上皮细胞。2. 在工程微流体小气道内产生具有生理传播速度和破裂频率的液体塞，并结合计算和实验评估由此产生的流体机械应力及其对细胞损伤的影响。3. 研究由液体堵塞繁殖/破裂介导的流体机械应力和细菌感染或高氧介导的炎症联合引起的协同细胞损伤。同时，评价表面活性剂作为减少细胞损伤的对策的效果。

DESCRIPTION (provided by applicant): 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 involves 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 micro fluidic 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 micro fluidic 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.