Microvesicles as risk markers for venous thrombosis.

Microvesicles (MVs) are small (0.1-1 µm) membrane vesicles released from activated cells. The surface of MVs can be highly procoagulant due to the presence of the procoagulant protein tissue factor (TF) and of negatively charged phospholipids, such as phosphatidylserine. This review focuses on the potential utility of plasma MVs as a biomarker of venous thrombosis. The majority of studies have not found a clear relationship between venous thrombosis and phosphatidylserine-positive MVs or platelet MVs. Conversely, TF-positive MVs are increased in patients with venous thromboembolism. Studies with pancreatic cancer patients suggest that elevated levels of TF-positive MVs may be predictive of the development of venous thrombosis and patient survival. However, further studies are needed to determine if TF-positive MVs are a good biomarker for venous thrombosis in cancer and other diseases.