Angiogenesis

Aaron Welch Professor Bowman BIOL 1014 18 April, 2011 Angiogenesis abnormalities What is angiogenesis' Angiogenesis is a very important natural process in the human body that can be quite beneficial but also drastically fatal. It is the growth of new capillary blood vessels in the body and is used for healing and reproduction. The body controls the angiogenesis process and tries to create a balanced cycle of growth and inhibitory factors. Without the balance between the two factors many times the process can become abnormal and blood vessel growth will be either excessive or insufficient. Over 1 billion people worldwide are affected by angiogenesis type disorders. We start with the actual process of angiogenesis which occurs in many steps. The first couple steps start when the diseased or injured tissue releases angiogenic growth proteins. Growth factors then bind to receptors on nearby blood vessels and the endothelial cells become activated. The cells machinery begins manufacturing new molecules like enzymes that dissolve tiny holes in the sheathing like covering. Endothelial cells begin dividing and migrating out through dissolved holes of the existing vessel and adhesion molecules serves as hooks to pull in the new blood vessel. The vessel then elongates and sprouting endothelial cells roll to form a blood vessel tube. Individual tubes connect and form a blood vessel loop in order to circulate blood. Muscle cells stabilize and support these tubes and blood flow begins. The results of abnormalities in the angiogenesis process can cause many different diseases and even lead to cancer. The process is off when the pro-angiogenic molecules are balanced with the anti-angiogenic molecules but on when the balance is favoring one or the other. There are various factors that change or decide whether the process switches on. Either due to: metabolic stress (low pH levels), mechanical stress (pressure from other cells), immune/inflammatory response (immune/inflammatory cells that have infiltrated the tissue), and genetic mutations (deletion of tumor-suppressor genes that control production of angiogenesis regulators) Cancerous tumor often arise when the process is over efficient and excessive. Angiogenesis has been closely studied in the last Century is now commonly known to be a main factor in tumors. Studies show that cells in pre-cancerous tissue acquire angiogenic substances on their way to becoming cancerous. Cancer thrives on angiogenesis, every cancerous tumor release angiogenic growth factor proteins. These proteins stimulate the blood vessels to indefinitely grow into the tumor and help it grow. This is the only way tumors are able to obtain oxygen and nutrients. Without blood vessels or the support of angiogenesis the cancerous tumors would not grow to a very critical size or have the ability to metastasize to another organ. Tumor vessels develop by sprouting from pre-existing vessels. They can also develop around an existing vessel to form a perivascular cuff which is an indication of inflammation. Strangely although when the tumors grow they do not acquire the same protective mechanisms that the normal vessel would develop. Cancer is the main focus when there is an excessive increase in the process of angiogenesis. Normally, the balance between these forces is tipped in favor of inhibition and consequently capillary growth is restrained. When there is insufficiency (inhibition) in the process there are many other complications that can arise also. When angiogenesis is insufficient blood vessel growth is not stable, and circulation is not adequately replenished, leading to the risk of tissue death. Alzheimer’s disease occurs from micro vascular degeneration an insufficiency of an angiogenic growth factor. Osteoporosis, also a very serious disease, is when Impaired bone formation due to age-dependent decline of VEGF, or vascular endothelial growth factor. Angiogenesis inhibitors prevent fracture healing which leads to the cause of osteoporosis. Systemic Sclerosis, which is when the body mistakenly targets healthy cells for destruction, is caused when angiogenesis insufficiently responds. Regulated for important biological circumstances in humans, Angiogenesis is a strictly balanced process that can be devastating if corrupted or changed. Abnormalities easily occur in the process, either with an insufficiency or with an excessive overdose. Many problems arise with angiogenesis abnormalities, and cancerous tumors are at the upper level. Many diseases also occur resulting from excessive or inefficiency that most people do not know. Angiogenesis is still being studied and yet many questions are still left unanswered due to always changing results.