Impacts of dynamic mechanical stretch on the expression of plasminogen activator inhibitor-1 (PAI-1) in human A549 cells

We investigated the expression of plasminogen activator inhibitor-1 (PAI-1) in A549 cells under cyclic mechanical stretch using cytomechanics. A cell stretch loading device was used to simulate mechanical ventilation conditions towards the in vitro cultured A549 cells, with stress loads of 10% and 20% and frequency of 0.3 Hz for 4, 12, and 24 h. Polymerase chain reaction and western blotting were then performed to measure the expression of PAI-1mRNA and protein; annexin V/propidium iodide flow cytometry was performed to detect apoptosis; an enzyme linked immunosorbent assay was performed to detect the expression of interleukin-8 in the supernatant; and electron microscopy was performed to observe changes in cell morphology. The expression of PAI-1mRNA and protein, cell early apoptosis rate, and interleukin-8 expression in the supernatant in each 20% stretch subgroup were increased compared to the corresponding control group, and cell damage was more obvious by electron microscopy observation. Mechanical stretch may damage A549 cells and upregulate PAI-1 expression.