肺泡化阻滞是研究BPD病理的关键点。肺肌成纤维细胞（MF）定向迁移至次级分隔顶端是肺由小管-囊泡期向肺泡期转变的必要步骤，而细胞极性的形成和稳定是细胞定向迁移的前提。我们前期在培养细胞中证实，LPS破坏了MF的极性，进一步使用蛋白质组学技术在LPS诱导的BPD模型中筛选出一系列表达异常的分子，并确认蛋白激酶Csk活性下调可影响细胞极性。Csk是调节细胞骨架重组的重要分子。据此，我们提出MF极性受到破坏是BPD肺泡化阻滞重要成因的新观点。本课题综合应用BPD模型，基因敲除细胞，基因过表达，time-lapse成像等手段，多角度阐明MF极性的建立与维持在肺泡化过程中的作用，探讨MF极性破坏和BPD之间的关系。在国内外同行及自身实验提示下率先提出一种新的细胞极性调控机制：Csk/Src 通过激活EGFR改变Cdc42活性和定位，进而影响细胞极性。本课题的实施将有助于理解肺发育和BPD的发病机理。

Bronchopulmonary dysplasia (BPD) is characterized by alveolar simplification with decreased alveolar number and increased airspace. As it is clear that alveolar myofibroblasts are critical for the formation of secondary septa, their absence are associated with a lack of secondary septation and alveolarization failure. Directional migration of myofibroblasts towards the tip of secondary septa is a critical step for transformation from canalicular-saccular to alveolar stage during lung development. It is known that formation and stability of cell polarity are required for directional migration. Our previous studies have demonstrated LPS exposure attenuated the polarized of alveolar myofibroblast in vitro.The expression profiles of protein chips indicated a group of factors were significantly changed in a rat model of BPD, including of C-terminal Src kinase( Csk), a repressor of Src. Csk / Src has emerged as key regulators of cytoskeletal rearrangements. We have also shown that down-regulated Csk activity and elevated Src activity indeed influenced myofibroblasts polarity in vitro. However, it remains unclear how Csk / Src control the formation and stability of myofibroblasts polarity. In this study, we attempt to address whether establishment and maintenance of myofibroblasts polarity are involved in the alveolarization. Furthermore, we investigated whether the defect in myofibroblasts polarity may contribute to the abnormal location of myofibroblasts in vivo and further arrest alveolar development in BPD. Finally, we are to study whether Csk / Src signaling regulates myofibroblasts polarity through EGFR, and lead to disrupt Cdc42 activity and location at the migrating cells. This study provides the first insight into the roles and potential mechanisms of myofibroblasts polarity in the pathogenesis of BPD and lung development.