Regulated secretion in endothelial cells: biology and clinical implications.

Vascular endothelial cells are critical participants in maintaining blood flow, with the ability to respond rapidly to injury. We have outlined above how the regulated secretion of a variety of hemostatic and inflammatory mediators contributes to these nearly instantaneous responses. The WPB are the most prominent of these regulated secretory granules, and there is growing evidence of additional granules that release their contents under a variety of conditions. The mechanisms responsible for the targeting of proteins to regulated secretory granules, and of exocytosis of these granules are being elucidated. EC appear to share some characteristics with other secretory cell types, but also are likely to have unique properties related to the storage and secretion of large multimeric proteins such as VWF and multimerin. Understanding these mechanisms may lead to new strategies for treating coronary artery disease, stroke, sickle cell disease, and hemophilia through drugs that modulate sorting and secretion, or by gene transfer approaches that introduce therapeutic molecules into the WPB for regulated release.