Angiogenesis Definition

Angiogenesis is a biological process where new blood vessels grow from ones already in place. During our lifetime, this physiological development takes place countless times during our development, as well as when we are sick in certain disease situations.

What is Angiogenesis?

• According to the Angiogenesis Network, angiogenesis "...is the process of formation new Blood Vessels from pre-existing vessels. Angiogenesis is a normal process in growth and development of blood vessels as well as wound healing. If tissues need more oxygen then they release molecules that encourage blood vessel growth. Tumors also follow the similar procedure to improve their own blood supply in order to reassure their aberrant growth."

  Scientists studying the process of angiogenesis are learning more, and more about switching it on and off in our bodies depending on what is being treated.

Where Does Angiogenesis Occur?

• "In physiological conditions, angiogenesis occurs primarily in embryo development, during wound healing and in response to ovulation," according to the Lymphedema People.

  With embryos, the development of new life needs an ever growing supply of blood to nourish the cells that are dividing at a rapid rate. Angiogenesis, or formation of new blood vessels, keeps pace with the growth of the baby.

  When we are wounded, such as a cut to the skin, angiogenesis is at work building new blood vessels at the injury site. This process is triggered by a cell's lack of oxygen and releases "angiogenic molecules" that call for other types of cells to come to their aid.

How Does Angiogenesis Work?

• In the case of wounds, such as a cut to the skin, angiogenesis works by building new blood vessels at the injury site. This process is triggered by a cell's lack of oxygen, and releases "angiogenic molecules" that call for other types of cells to come to their aid. The endothelial cells that rush to the injury cite form new blood vessels. Endothelial cells are cells that line the interior surface of all blood vessels, and the heart.

  According to lymphedemapeople.com, as differentiation occurs, they secrete matrix metalloproteases (MMP) that eat blood-vessel walls enabling them to escape and move to the site where assistance is needed. Other protein fragments are produced from the digestion of the blood vessel walls increasing endothelial cell activity. These endothelial cells eventually become small capillaries restoring blood-flow to the site.

Disease and Angiogenesis

• Scientists have developed medications to inhibit angiogenesis. Stopping the development of blood vessels would seem like a bad thing to do, but in the case of solid cancer tumors this is needed.

  Tumors need a blood supply like any other cells in the body, and restricting, or eliminating the supply compromises the tumor's viability. There are chemicals available, and being tested to turn off angiogenesis in the body. Endostatins, proteins made naturally by our bodies, are anti-angiogenic. The drug thalidomide, used in the 50's and 60's that caused many birth defects when given to pregnant women, is another anti-angiogenic agent being tested.

  According to the Angiogenesis Foundation, the U.S. Food and Drug Administration (FDA) approved the use of the anti-angiogenic drug bevacizumab (Avastin) for renal cell carcinoma, cancer of the kidney.

Natural Activators of Angiogenesis

• There are naturally occurring stimulators of angiogenesis, and according to the National Cancer Institute the ones identified are:

  Proteins: Acidic fibroblat growth factor, angiogenin, basic fibroblast growth factor (bFGF), epidermal growth factor, Interleukin 8, placental growth factor, platelet-derived endothelial growth factor, scatter factor, transforming growth factor alpha, tumor necrosis factor alpha, and vascular endothelial growth factor (VEGF).

  Small Molecules: adenosine, 1-Butyryl glycerol, nicotinamide, prostaglandins E1 and E2