Tissue factor (TF) plays an essential role in hemostasis. Perivascular cells express TF and provide a hemostatic barrier around all blood vessels to rapidly activate coagulation following injury. Exposure of TF to blood leads to the formation of a hemostatic plug. In addition, TF is expressed in a tissue-specific manner with high levels in the heart, brain, lung, uterus, placenta, and testis (Figure 3). This pattern of TF expression suggests that some tissues require additional hemostatic protection, possibly due to vessel damage from mechanical injury that may occur in the lung and heart. In fact, TF deficiency has not been reported in humans, suggesting TF is essential for life.
Figure 3: Model of Tissue Specific Hemostasis