Thrombosis occurs when a blood clot forms (partial or complete blockage) within a blood vessel, whether venous or arterial, restricting the natural flow of blood and causing clinical complications. The complex homeostasis that occurs between blood cells (including platelets), plasma proteins, coagulation factors, inflammatory agents and cytokines, and the endothelial lining within the lumen of arteries and veins is essential for blood to flow freely in vessels. When this physiologic mechanism is disrupted, the likelihood of having a thrombosis rather than a coagulopathy increases (increased risk of bleeding). In affluent countries, acute venous and arterial thrombosis constitute the leading cause of death. The mortality rate varies depending on where the thrombus is located and how severe it is.
The importance of the vascular smooth muscle cell in modulating vascular tone in resistance arteries was recognised. Vascular biology successfully combined basic and clinical sciences, revealing the significance of oxidative stress in endothelial dysfunction and vascular inflammation as a crucial unifying factor. The first is various systems to observe neo-angiogenesis, and the second is gene targeting technology. Recent progress in vascular biology has been heavily supported by two different experimental systems that allow manipulation of in vivo angiogenesis; the first is various systems to observe neo-angiogenesis, and the second is gene targeting technology.