Abstract
The contribution of vessel wall-derived tissue factor (TF) to atherothrombosis is
well established, whereas the pathophysiological relevance of the blood-borne TF is
still a matter of debate, and controversies on the presence of platelet-associated
TF still exist. In the past 15 years, several studies have documented the presence
of TF in human platelets, the capacity of human platelets to use TF mRNA to make de
novo protein synthesis, and the increase in the percentage of TF positive platelets
in pathological conditions such as coronary artery disease (CAD). The exposure of
vessel wall-derived TF at the site of vascular injury would play its main role in
the initiation phase, whereas the blood-borne TF carried by platelets would be involved
in the propagation phase of thrombus formation. More recent data indicate that megakaryocytes
are committed to release into the bloodstream a well-defined number of TF-carrying
platelets, which represents only a fraction of the whole platelet population. These
findings are in line with the evidence that platelets are heterogeneous in their functions
and only a subset of them is involved in the hemostatic process. In this review we
summarize the existing knowledge on platelet associated TF and speculate on its relevance
to physiology and to atherothrombosis and CAD.
Keywords
tissue factor - platelets - megakaryocytes - atherothrombosis - coronary artery disease
