Growth Factors

Growth Factor is a protein molecule made by the body; it functions to regulate cell division & cell survival. Growth factors can also be produced by genetic engineering in the laboratory and used in biological therapy.

Growth factors bind to receptors on the cell surface, with the result of activating cellular proliferation and/or differentiation. Growth factors are quite versatile, stimulating cellular division in numerous different cell types; while others are specific to a particular cell-type. Growth factors are proteins that promote cell growth.

Growth factors are proteins that function as growth stimulators (mitogens) and/or growth inhibitors, stimulate cell migration, act as chemotactic agents, inhibit cell migration, inhibit invasion of tumor cells, modulate differentiated functions of cells, involved in apoptosis, involved in angiogenesis and promote survival of cells without influencing growth and differentiation.

Growth factors secret diffusible factors that are identified in the conditioned medium of cell cultures. Growth factors are present in membrane-anchored forms. Growth factors act in an autocrine, paracrine, juxtacrine or retrocrine manner.

Usually researchers use the term growth factors as a synonym for cytokines.

Examples for Growth Factors are EGF, FGF, NGF, PDGF, VEGF, IGF, GMCSF, GCSF, TGF, Erythropieitn, TPO, BMP, HGF, GDF, Neurotrophins, MSF, SGF, GDF and more.

Hematopoietic growth factors are hormone-like substances that stimulate bone marrow to produce blood cells. Shortages of blood cells cause most of the symptoms in people with MDS, the use of growth factors is very appealing. Studies have tested several growth factors in patients with MDS, such as granulocyte colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF).

Erythropoietin is a growth factor which promotes red blood cell production. Recently it has been found that combining erythropoietin with G-CSF improves the response to the erythropoietin. Interleukin-11 (IL-11) stimulates platelet production after chemotherapy. Current studies try to find the best way to predict which growth factors will treat new diseases and the best way to combine growth factors with each other and with other treatments, such as chemotherapy or hormones.

Growth factors produce extra stem cells before a stem cell harvest. Chemotherapy kills off healthy white blood cells, as well as the leukaemic ones, therefore there is risk of infection while white cell count is low. Low level of white cells is called ‘neutropenia’. Early research of growth factors shown that, while growth factors help the white cell count to recover, they actually don’t make much difference to the number of infections.

Growth Factors are biologically active poly-peptides which function as hormone like regulatory signals, controlling the growth and differentiation of responsive cells. The distinction between growth factors and hormones is frequently arbitrary.

The sequence of amino acids permits growth factors to be placed into families, suggesting that they evolved from a single ancestral protein. The insulin family comprises somatemedins A and C, insulin, insulinlike growth factor (IGF), and multiplication-stimulating factor (MSF). A 2nd family consists of sarcoma growth factor (SGF), transforming growth factors (TGFs), and epidermal growth factor (EGF). In addition, there are growth factors, such as nerve growth factor (NGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF), for which structural homologs have not been identified.

Stimulation of cell proliferation growth factors is similar to the rapid cell proliferation characteristic of tumor cells. Growth factor receptors are similar to the tumor-causing proteins produced by several RNA tumor viruses. Platelet-derived growth factor ( PDGF) is virtually identical to the tumor-causing protein of the RNA tumor virus, simian sarcoma virus.

Growth Factors are involved in cell differentiation and are essential to normal cell cycle, and are thus vital elements in the life of animals from conception to death. Growth Factors mediate fetal development, play a role in maintenance and repair of tissues, stimulate production of blood cells & participate in cancerous processes.