Summary
Local fibrinolytic changes in atherosclerotic arteries have been suggested to influence plaque growth and promote mural thrombosis on ruptured or ulcerated plaques. Increased levels of plasminogen activator inhibitor (PAI-1) have been found in atherosclerotic arteries. In this study tissue plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA) and PAI-1 were localized in arterial biopsies of healthy and atherosclerotic vessels by immunohistochemis-try. The expression of fibrinolytic regulators was related to the distribution of endothelial cells (EC) and macrophages. Results: t-PA was expressed in vasa vasorum. PAI-1 was positive in endothelial cells, in the media and in the adventitia. Increased expression of t-PA, u-PA and PAI-1 was found in atherosclerotic vessels. t-PA, u-PA, PAI-1 and macrophages were co-localized in plaques. These results support the concept that macrophages can be important in the local regulation of fibrinolysis in atherosclerotic vessels.
