Angiogenesis is the process of producing new blood capillaries from pre-existing blood vessels, as stated by The Angiogenesis Foundation. Angiogenesis is an important process in healing and reproduction, but abnormal blood vessel growth can be harmful, as in the case of cancer and diabetic ulcers.
Blood vessels have several "on" or "off" switches that regulate the growth of new blood vessels, according to News Medical. The "on" switches are called angiogenesis growth factors and the "off" switches are called angiogenesis inhibitors. In a normal body, these switches are balanced to prevent abnormally high or low blood vessel growth. A healthy example of angiogenesis is the increase of angiogenesis growth factors for the repair of wounds or the formation of the placenta during pregnancy.
An imbalance of these switches can be harmful. For example, malignant tumors can activitate angiogenetic growth factor, causing the body to produce new blood vessels that provide oxygen and nutrients to the tumor. These new blood vessels can carry cancer cells away from the original tumor site, causing the disease to spread, as noted by News Medical. Oncologists employ anti-angiogenic therapies to prevent the formation of new blood vessels at the tumor site, reports the Autogenesis Foundation.