ROLE OF THROMBIN IN ENDOTHELIAL-CELL MONOLAYER REPAIR IN-VITRO

Purpose: We examined the effect of thrombin on human iliac artery endo thelial cell monolayer repair and proliferation after denuding vascula r injury. Methods: Human iliac artery endothelial cell monolayer repai r was determined by scrape wounding confluent monolayers and measuring the advancement of the cells into the wounded area for 3 days. Prolif eration studies involved plating human iliac artery endothelial cells at one tenth confluence and counting the increase in cell number every 2 days for a 2-week period. Proliferation during monolayer repair was examined by determining bromodeoxyuridine uptake in cells located at the leading edge of a scrape-wounded monolayer. Results: Thrombin (1 t o 8 U/ml) inhibited human iliac artery endothelial cell monolayer repa ir in a concentration-related, reversible manner. The effect was augme nted by decreasing serum concentration and was independent of the pres ence of endothelial cell growth supplement. Inactivation of thrombin's proteolytic site with diisopropylfluorophosphate eliminated its effec t on monolayer repair. Thrombin (0.5 to 8 U/ml) inhibited human iliac artery endothelial cell proliferation in a dose-related manner. This e ffect was augmented by decreasing serum concentration. Finally, thromb in (4 U/ml) inhibited the proliferative response of cells located at t he leading edge of wounded monolayers compared with control groups. Co nclusion: Thrombin inhibits human arterial endothelial cell monolayer repair and proliferation after denuding vascular injury.