Microfluidic Tissue Engineering of Small Airway Injuries

描述(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，液体塞子形成堵塞的桥梁，阻塞呼吸道并扰乱气体交换。咳嗽时，这些桥梁移动，呼吸道重新开放，机械力传递到呼吸道上皮细胞。同样，在同时涉及呼吸道和肺泡腔的环境中，如肺炎或充血性心力衰竭，或低潮气量的机械通气，会有较小的呼吸道周期性关闭和重新开放，这可能是听诊器很容易听到的爆裂声。然而，这些重新开放事件所产生的爆炸性瞬时压力波的细胞水平的影响以前还没有被研究过，尽管相关的塞子破裂可能产生巨大的压力，并且是肺损伤的主要原因。这项建议将从实验和理论上研究流体机械应力在使用微工程气道重新开放气道期间对呼吸道上皮细胞的有害影响。具体的假设是，在小气道重新开放过程中，液体塞在小气道系统中的移动和破裂将产生大量的流体机械应力并损伤气道上皮细胞，即使在正常情况下亚致死量的流体机械应力在其他物质如细菌或高氧介导的炎症存在时也会变得致命，从而扩大损伤的区域和严重程度。该方案的具体目的是：1.设计和制造一种仿生微流控系统，用于在生理气液界面条件下进行呼吸道上皮细胞的体外培养。2.在工程微流控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所产生的流体机械应力及其对细胞损伤的影响。3.研究液体塞传播/破裂介导的流体机械应力与细菌感染或高氧介导的炎症相结合所造成的协同细胞损伤。此外，评估表面活性物质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.