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Growth Factors are something in the body that is there naturally which allow or deny cell growth. These factors are normally made up of cell hormones or other proteins within the body.

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History

In 1855, Rudolf Virchow was studying how the cell divides when he made a discovery. This discovery was that there happened to be something motivating the cell division, which he called growth factors. At the time, the biological mechanisms behind the growth factors, and how it connected to cell division was still unknown. Due to this discovery, many scientists then created experiments to show how cell division and growth factors could be linked to one another.

Scientist’s success of identifying a new kind of growth factor have been rewarded in many ways, one way is Nobel Prize. One such case was the 1986 Nobel Prize in Physiology and Medicine. The award was given to Stanley Cohen and Rita Livi-Montalcini at the Karolinska Institute for discovering epidermal growth factor and nerve growth factor.

Function

Growth factors are substances that are created naturally and help to control and control cells (the building blocks of life). Growth factors prevent cells from over populating (having to many) in one particular area or help to signal if more cells need to be made. Growth factors are an important mechanism that acts as the maintenance department for any given system of the body (such as the Nervous system, Circulatory system, and Respiratory system.)

Subject to where in the body and which system you are trying to control, different growth factors will be found. In the nervous system for instance there is a nerve growth factor. This is due to the nature that cells need to be specially designed for one job. These specialized growth factors can be turned on and will promote a certain group of cells to populate that area. Growth factor is very important for the body to behave correctly. Due to the growth factors ordering which parts of our cell structures need more cells. Without growth factor, our cells would all die off without creating any offspring to take over the function that cell once maintained. Growth factors control and oversee the process of cells talking to each other. This makes it so the cells can multiply themselves until the body no longer needs any more of them.

In addition, growth factors can be affected by chemicals that are not normally in the body. These chemicals are introduced into the body’s system by acts such as smoking, drinking, and substance abuse. When these chemicals enter the body it can cause the growth factors to act differently by creating many cells that never kill themselves off. This is dangerous to the cell because if there are too many cells that over populate an area a tumor is created. If this tumor is created the growth factors will no longer act in the typical way, resulting in more tumors, bronchitis, or even cancer.

Types

There are many different types of growth factors in the body. Some can be altered to be harmful while others are never harmful. A change in the growth factor can sometimes cause alterations so harmful that tumors are created. Other growth factors can causing damage to the cell, such as transforming growth factor beta found to be activated when brain tissue damage is there.

Different types of growth factors (GF) include epidermal growth factor (EGF), fibroblast growth factor (FGF), hepatocyte growth factor (HGF), insulin-like growth factor (IGF), nerve growth factor (NGF), transforming growth factor alpha(TGF-α), transforming growth factor beta (TGF-β), or vascular endothelial growth factor (VEGF). These different types of growth factors have sub systems. There are many parts to a growth factor for it to perform the specific function correctly. Many have sub growth factors and scientists do not fully understand the system as of yet. New growth factors are being discovered constantly and added to the list of growth factors. For certain growth factors much is known, others the discovery has just been made so all that is known is that it exists and what system of the body it can be connected to.

Types of Growth Factors	Effects
Epidermal Growth Factor	This growth factor is a protein that is involved in cell growth, oncogenesis, and healing of wounds on the body. It consists of a string of 53 amino acids.
Fibroblast Growth Factor	A polypeptide growth factor that are found in many organisms including humans with a range of length in amino acid chains. This growth factor helps cells multiply and aids in wound healing.
Hepatocyte Growth Factor	HGF controls functions as a trigger to activate cell death, or cell growth. This growth factor is present in Mesenchymal stem cells. It is helpful with tissue healing, blood vessel renewal, and the formation of tumors.
Insulin-like Growth Factor	A growth factor that acts like insulin and performs all of the acts that insulin would do in the cell. It is also responsible for the growth hormone multiplication and regulation.
Nerve Growth Factor	A growth factor that multiplies and controls the nerve cells of the body. It is helpful to aid in healing of wounds of the body when there is no feeling in that region.
Transforming Growth Factor Alpha	This growth factor competes with EGF as it likes the same receptors. TGF-a also helps with wound healing and has been known to be found in some types of cancers.
Transforming Growth Factor Beta	This growth factor helps with the overall life of a cell and helps with the body building immunity. It also aids with the regulation of cells and controls the life time of cells.
Vascular Endothelial Growth Factor	Due to alternative splicing this growth factor helps the body control endothelial cells. It tells those cells when to multiply, where to move, and also the ability to stop the cell division process altogether.

Further Reading

• Marinas, AE. Ciurea, P. Margaritescu, C. Expression of Epidermal Growth Factor and its receptors in chronic bronchitis. Romanian Journal of Morphology & Embryology [Online] December 17, 2012, p. 957-966.

• Nabil, S. Sue, Y. Missak, H. Monoclonal Antibodies against Epidermal Growth Factor Receptor in Solid Tumors. US National Library of Medicine [Online] December 16, 2012, p. 1-9.

• Zhao, L., Xu, K., Wang, S., Hu, B., Chen, L. Pathological significance of epidermal growth factor receptor expression and amplification in human gliomas. Histopathology [Online] February 23, 2012, p. 726-736.

• Yeganeh, B. Mukherjee, S. Moir, L. Kumawat, K. Novel non-canonical TGF-beta signaling networks: Emerging roles in airway smooth muscle phenotype and function. Pulmonary Pharmacology & Therapeutics [Online] February 2013, 50-63.