CO₂ promotes plasminogen activator inhibitor type 1 expression in human mesothelial cells

Background: Previous observations have indicated that CO₂ insufflation increases peritoneal plasminogen activator inhibitor type 1 (PAI-1) expression. Methods: Primarily cultured human peritoneal mesothelial cells were exposed to either flowing or pressurized CO₂ for 90 min. Unexposed cultures served as controls. Samples of cell culture media were taken at 0, 5, and 24 h after exposure to measure media pH, PAI-1, and tissue-type plasminogen activator (t-PA) protein release. Simultaneous samples were taken to measure PAI-1 and t-PA mRNA expression. Results: Mesothelial cells exposed to flowing CO₂ released more PAI-1 than those exposed to pressurized CO₂ (p < 0.001) and controls (p < 0.001). Cells exposed to flowing CO₂ had an increased PAI-1 mRNA expression at 5 h. Conclusions: CO₂ increased mesothelial cell PAI-1 expression involving a transcriptional mechanism. These findings might provide a mechanism for adhesion formation and cancer progression following laparoscopic surgery.