Effects of mechanical stretch preconditioning on pathological stretch-induced damage to type II alveolar epithelial cells

Abstract

Objective To evaluate the effects of mechanical stretch preconditioning on pathological stretch-induced damage to type Ⅱ alveolar epithelial cells.Methods A549 cells cultured in vitro were randomly divided into 6 groups (n =5 each)using a random number table:control group (Ⅰ group),pathological stretch group (Ⅱ group) and different time mechanical stretch preconditioning + pathological stretch group (group Ⅲ-Ⅵ).A549 cells were exposed to 20％ cyclic stretch at 0.3 Hz for 6 h in Ⅱ group.In Ⅲ-Ⅵ groups,A549 cells were exposed to 5％ cyclic stretch at 0.3 Hz for 15,30,60 and 120 min,respectively,and then exposed to 20％ cyclic stretch at 0.3 Hz for 6 h.After the end of pathological stretch,the apoptosis in cells was detected using flow cytometry and was calculated.F-actin expression was determined using flow cytometry.Results Compared with group Ⅰ,the apoptosis rate was significantly increased,and the expression of F-actin was up-regulated in Ⅱ group.Compared with group Ⅱ,the apoptosis rate was significantly increased in groups Ⅳ-Ⅵ,and the expression of F-actin was up-regulated in groups Ⅴ and Ⅵ.Conclusion Preconditioning with mechanical stretch (30-120 min) can mitigate pathological stretch-induced damage to type Ⅱ alveolar epithelial cells. Key words: Biomechanics ; Ischemic preconditioning; Epithelial cells ; Pulmonary alveoli