[Mormorphological and functional changes of lung cells in hyperoxia environment]

To observe the morphological and functional changes of different lung cells in hyperoxia environment.

Type II alveolar epithelial cells (AEC II) and lung fibroblasts (LFs) of fetal rats with 18 days old were isolated and cultured in vitro, and divided into air group (placed in an atmospheric incubator, and culturing with oxygen volume fraction of 0.21) and hyperoxia group (placed in a high oxygen culture chamber, and culturing with oxygen volume fraction of 0.90). Morphological changes of two kinds of cells were observed under microscope. Cell migration was observed by scratch test. The levels of reactive oxygen species (ROS) and apoptosis in cells were detected by flow cytometry.

After 8 hours of hyperoxia, the volume of AEC II increased and the cells were loosely arranged; the clearance of LFs cells was increased and arranged in disorder. Scratch test showed that, compared with air group, the immigration rate of AEC II was inhibited at 6 hours hyperoxia [migration rate: (38.67±1.15)% vs. (58.67±2.31)%, P < 0.01], the immigration rate of LFs was promoted at 12 hours after hyperoxia [migration rate: (55.37±1.50)% vs. (46.90±1.20)%, P < 0.01]. With the increase of hyperoxia time, intracellular ROS contents of two cells were gradually increased, which were significantly higher than those of the air group (fluorescence intensity: 130.67±4.04 vs. 54.67±2.51, 85.00±2.00 vs. 60.33±1.52, both P < 0.01). Both two kinds of cells showed apoptosis after exposure to high oxygen, the apoptosis rate of AEC II at 2 hour exposure were significantly higher than that of air group [(1.93±0.28)% vs. (1.07±0.11)%, P < 0.05], the apoptosis rate of LFs at 6 hour exposure was significantly higher than that of air group [(1.66±0.09)% vs. (1.46±0.09)%, P < 0.05].

High concentration of oxygen can cause poor growth of lung cells, reduce AEC II migration level and increase LFs migration, and the production of intracellular ROS eventually leads to apoptosis of lung cells.