The topic of human growth factor (HGF) is exceedingly complicated. The physiological intricacies of the varying HGFs and their actions challenge any layperson’s comprehension. Nonetheless, because the use of HGF seems to be the direction some skin-care companies are taking, and because there is a large body of research showing its efficacy for wound healing (but not for wrinkles), it does deserve comment.
HGFs make up a complex family of hormones that are produced by the body to control cell growth and cell division in skin, blood, bone, and nerve tissue. Most significantly, HGFs regulate the division and reproduction of cells, and they also can influence the growth rate of some cancers. HGFs occur naturally in the body, but they also are synthesized and used in medicine for a range of applications, including wound healing and immune-system stimulation. HGFs are chemical messengers that bind to receptor sites on the cell surface (receptor sites are places where cells communicate with a substance to let them know what or what not to do). HGFs must communicate with cells to instruct them to activate the production of new cells, or to instruct a cell to create new cells that have different functions. Another way to think of HGFs is that they are messengers designed to be received or “heard” by specific receptor sites or “ears” on the cell. HGFs, such as transforming growth factor (TGF, stimulates collagen production) or epidermal growth factor (EGF, stimulates skin-cell production), play a significant role in healing surgical wounds. The main task of HGFs is to cause cell division, which is helpful; however, at certain concentrations and over certain durations of application they can cause cells to over-proliferate, which can cause cancer or other health problems.
But what happens when you put HGFs on skin, particularly TGF and EGF, which some cosmetic companies are using? The risk is that they could accelerate the growth of skin cancer by stimulating the overproduction of skin cells. In the case of TGF, which stimulates collagen production, it can encourage scarring, because scars are the result of excessive collagen production, and if you make too much collagen you get a scar or a knot on the skin such as a keloidal scar. Most of the research on the issue of HGFs for skin has looked primarily at the issue of wound healing, and at short-term use of HGFs. In skin-care products, however, they would be used repeatedly, and possibly over long periods of time. A shortcoming of HGFs, according to an article by Dr. Donald R. Owen in Global Cosmetic Industry (March 1999), is that “The body produces these [HGFs] in exquisitely small concentrations at just the right location and time .... Actual growth factors such as [EGF and TGF-B] are [large] configurations, which do not penetrate the skin .... They [also] lose their activity within days in water or even as solids at normal temperatures .... [Yet], even after all these complications, the siren’s song is too strong. We [the cosmetics chemists] will use them.” According to Drs. H. Ray Jailan, MD and Jenny Kim, MD, PhD, “many cosmeceuticals now contain various growth factors including EGF, insulin-like growth factor, platelet growth factor, and keratinocyte growth factor. Although these growth factors can theoretically induce keratinocyte differentiation and dermal remodeling, whether any of the products available to consumers demonstrate significant clinical effectiveness in preventing or reversing photoaging has not been established.” The doctors went on to state “Whether the TGF-B and other growth factors contained in cosmeceuticals are stable, can be absorbed adequately, or exert a functionally significant outcome to induce dermal remodeling and reverse photoaging [wrinkles] is unclear since well-controlled clinical studies are lacking.”
The research into HGFs is without question intriguing, but much remains unknown at this time, especially in terms of long-term risk or stability when they are used in cosmetics and applied to skin. In this arena, if cosmetics companies continue to use HGFs, it is the consumer who will be the guinea pig. (Sources: Journal of Cosmetic and Laser Therapy, June 2008, pages 104–109; Journal of Burn Care and Rehabilitation, March–April 2002, pages 116–125; Journal of Dermatologic Surgery and Oncology, July 1992, pages 604–606; Journal of Anatomy, July 2005, pages 67–78; International Wound Journal, June 2006, pages 123–130;Tissue Engineering, January 2007, pages 21–28; Wounds, 2001, volume 13, number 2, pages 53–58; Plastic and Reconstructive Surgery, August 1995, pages 251–254, and September 1997, pages 657–664; Skin Pharmacology and Applied Skin Physiology, January–April 1999, pages 79–84; Journal of Surgical Research, April 2002, pages 175–182; and Cosmetic Dermatology, Second Edition, McGraw Hill Medical, Baumann, Leslie, et. al.,2009, pages 23–24).