肺血管内皮损伤是ARDS重要病理生理改变，是导致不良预后的关键。自噬是其损伤的重要环节。近来研究显示，FOXO1是促进细胞自噬的关键核转录因子。预试验表明，ARDS肺血管内皮细胞FOXO1及其下游自噬靶点SESN3表达增高。抑制自噬、促进肺血管内皮修复是ARDS的治疗方向。本课题组既往研究发现，MSC旁分泌HGF促进ARDS肺血管内皮的损伤修复，但机制不明。有研究显示，HGF与c-Met结合，激活Akt，促进FOXO1磷酸化并降解。我们推测MSC旁分泌HGF调控Akt/FOXO1通路、抑制ARDS肺血管内皮自噬、促进肺血管内皮修复。本研究拟在MSC与肺血管内皮细胞共培养和ARDS小鼠模型上，利用慢病毒转染调控MSC对HGF的分泌，体外及在体实验观察ARDS时MSC旁分泌HGF对Akt/FOXO1通路的调控和对肺血管内皮自噬与修复的影响，为提高MSC对ARDS肺血管内皮损伤的疗效提供新思路。

Pulmonary vascular endothelial injury is a critical pathophysiological mechanism in ARDS leading to poor prognosis. Autophagy is the key progress to its damage. Recent studies have reported that FOXO1 is a key nuclear transcription factor of autophagy improvement. Preliminary experiments showed that the expression of FOXO1 and its downstream autophagy target SESN3 were increased in ARDS. Inhibition of autophagy and promoting pulmonary vascular endothelium repairment is the new direction of ARDS treatment. Our previous studies have found that MSC-secreted HGF promoted pulmonary vascular endothelium repairment in ARDS with unclear mechanisms. It has shown that HGF binding to c-Met activates Akt and thus promotes FOXO1 phosphorylation and degradation. We hypothesize that MSC-secreted HGF improves endothelial barrier via regulation of Akt / FOXO1 pathway and inhibition of pulmonary vascular endothelial autophagy in ARDS. In this study, we will observe MSC-secreted HGF improvement capacity of pulmonary vascular endothelial injury regulating with Akt/FOXO1 pathway and autophagy in vitro and vivo, with MSC and pulmonary vascular endothelium co-culture model and gene modification of HGF knockout mouse. These provide a novel therapy for treatment of MSC in ARDS-injured pulmonary vascular endothelium.