Your bleeding heart: lessons from low tissue factor expression in mice.

Tissue factor (TF) is the cellular receptor and cofactor for blood coagulation factor VII (FVII). Exposure of flowing blood to cells that express TF leads to the initiation of blood coagulation. A recent study of mice expressing low levels of TF has demonstrated the importance of TF and FVII in maintaining adequate haemostasis within the heart. In addition, the study indicates that the heart is subject to a succession of minor bleeds most probably as a result of repetitive minor mechanical injury to the blood vessels.