In vivo induction of endothelial apoptosis leads to vessel thrombosis and endothelial denudation - A clue to the understanding of the mechanisms of thrombotic plaque erosion

Background - The mechanisms of thrombosis on plaque erosion are poorly understood. We examined the potential role of endothelial apoptosis in endothelial erosion and vessel thrombosis. Methods and Results - Segments of New Zealand White rabbit femoral arteries were temporarily isolated in vivo. One artery was incubated with staurosporin for 30 minutes, whereas the contralateral artery was incubated with saline and served as control. Three days later, thrombosis was evaluated angiographically and histologically. TUNEL score in the endothelial layer was significantly increased in staurosporin-treated arteries compared with controls (2.43 +/- 0.30 versus 0.93 +/- 0.44, respectively; P = 0.001). Large areas of endothelial denudation were detectable in staurosporin-treated vessels, whereas endothelium integrity was almost preserved in the saline group. Vessel thrombosis occurred in 58% of staurosporin-treated arteries ( 7 of 12) but in only 8% of saline-treated segments ( P < 0.01). Immunoreactivities for tissue factor, platelets, and fibrin were detectable within the thrombus. Addition of ZVAD-fmk (0.1 mmol/L) significantly reduced the occurrence of thrombosis ( 1 of 7 arteries or 14%, P = 0.04). These results were confirmed in balloon-injured atheromatous arteries. Conclusions - In vivo induction of endothelial apoptosis leads to both vessel thrombosis and endothelial denudation. Endothelial apoptosis may be a critical step in the transition from a stable endothelialized plaque to plaque erosion and thrombosis.