What is Angiogenesis?

Angiogenesis refers to the formation of new blood vessels from the development of existing capillaries or posterior veins of capillaries, mainly including: degradation of vascular basement membrane during activation; activation, proliferation, and migration of vascular endothelial cells; reconstruction to form new blood vessels And vascular network, is a complex process involving many molecules of many cells. Angiogenesis is a complex process of the coordinated action of pro-angiogenic factors and inhibitors. Normally, the two are in a state of equilibrium. Once this balance is broken, the vascular system will be activated, resulting in excessive angiogenesis or inhibition of the vascular system and degeneration of blood vessels.

Angiogenesis

Tumor angiogenesis is an extremely complicated process, which generally includes vascular endothelial matrix degradation, endothelial

Hypoxic tumor cells have increased tolerance to radiation: Hypoxic cells have reduced production of reactive oxygen species after irradiation. Since the damage of radiation to tumor cell DNA mainly depends on reactive oxygen radicals, hypoxic tumors often resist radiation. Not sensitive.

Radiation therapy not only has direct or indirect killing effect on tumor cells, but also has the effect of sealing tumor blood vessels, which can degrade and degenerate vascular endothelial cells. As the tumor shrinks, the tumor microvasculature becomes more tortuous, deformed, the lumen shrinks, the blood flow is slow, and thrombosis forms, which makes the tumor hypoxia worse.

Radiation therapy itself can also cause tumor angiogenesis to be active and increase VEGF secretion.