PLATELET-ADHESION TO AORTIC ENDOTHELIAL-CELLS IN-VITRO AFTER THROMBINTREATMENT - OBSERVATION WITH VIDEO-ENHANCED CONTRAST MICROSCOPY

Secondary thrombus formation following arterial occlusion is suggested to play an important role in the exacerbation of ischemic organ damag e, We investigated the effect of thrombin on endothelial cells from th e aspect of morphological changes and induction of platelet adhesion t o the endothelial cells. Using a video-enhanced contrast microscopy, w e observed human aortic endothelial cells (HAEC) following perfusion o f human oi-thrombin of 1.0 U/ml (n=7) or vehicle (n=7) for 30 minutes. The endothelial cells began to shrink 15 minutes after thrombin admin istration. Gaps between the cells were formed. The cells became rearra nged orderly in the same direction 30 minutes later. In another study, following pretreatment with human cx-thrombin 1.0 U/ml (n = 10) or ve hicle (n =7) for 20 minutes and washout, platelets were perfused over HAEC for 30 minutes, Platelets adhered directly to thrombin-treated en dothelial cells and became flat on the endothelial cells. Then other p latelets were observed to approach to the flattened platelets and aggr egated onto it. After washout of floating platelets, adhesion of plate lets was further confirmed, These results suggest that thrombin may be involved in the endothelial damage and formation of platelet thrombi on the endothelial cells after blood flow disturbance. (C) 1998 Elsevi er Science Ltd.