Thromboregulation by endothelial cells: significance for occlusive vascular diseases. Arterioscler Thromb Vasc Biol 21:178–182

Abstract—During their 7- to 9-day lifespan in the circulation, platelets perform an ill-defined baseline function that maintains the integrity of the vasculature. In thrombocytopenic states, there is an increase in vascular permeability and fragility, which is presumably due to absence of this platelet function. In sharp contrast, biochemical or physical injury in the coronary, carotid, or peripheral arteries induces platelet activation and platelet recruitment, which can progress to thrombotic vascular occlusion. Because there is 1 death every 33 seconds from vascular occlusion in the United States, this problem has critical public health implications. In this review, we describe the characterization of a novel potential antithrombotic agent with a unique mode of action—biochemical “deletion ” of ADP from an activated platelet releasate, which thereby inhibits platelet recruitment and further activation. (Arterioscler Thromb Vasc Biol. 2001;21: 178-182.) Key Words: endothelial cells n thrombosis n platelets n CD39/ecto-ADPase Several years ago, in the course of studying interactionsbetween cells of the vascular wall and those in the circulation, we demonstrated that platelets in proximity to endothelial cells do not respond to any added agonist in vitro. Experiments initiated in the late 1980s cumulatively led to the conclusion that endothelial cell CD39, an ecto-ADPase, wa