Physiological role of vessel wall related antithrombotic mechanisms: contribution of endogenous and exogenous heparin-like components to the anticoagulant potential of the endothelium.

The intact vessel wall provides diverse anticoagulant mechanisms which, together with circulating components, are actively and dynamically involved in the regulation of the haemostatic system. These mechanisms are able to specifically and co-operatively counteract various procoagulant inducers at localized sites, such that under physiological conditions the endothelium provides a non-thrombogenic surface. Upon activation of the haemostatic system, these different components help to limit the extent of the prothrombotic response of blood coagulation at the site of injury and thereby contribute on different molecular levels to the overall anticoagulant potential of the endothelium. Heparin and possibly vessel wall related glycosaminoglycans may modulate or even enhance some of these anticoagulant mechanisms. A detailed understanding of the molecular architecture of these different processes in vitro may thereby lead to possible new therapeutic regimens.