Role of growth factors in skin creams
What are growth factors?
Growth factors are proteins that regulate cellular growth, proliferation and differentiation under controlled conditions. They play an important part in maintaining healthy skin structure and function.
Growth factors are secreted by all cell types that make up the epidermis (outer layer of skin) and dermis (the layer of skin between the epidermis and subcutaneous tissue) of the skin including keratinocytes, fibroblasts and melanocytes.
How do growth factors work?
- They stimulate biochemical pathways that promote skin tissue repair and regeneration.
- They promote the formation of collagen and elastic fibres which give the skin its softness and suppleness.
- Synergistic interaction of multiple growth factors with other proteins in epidermis and dermis results in skin repair and regeneration.
- No single growth factor is solely determinant in the outcome of skin rejuvenation.
Growth factors applied to the skin surface penetrate the epidermis and in theory should ‘fertilise’ your skin.
What are the uses of topical skin creams containing growth factors?
Topical skin creams containing endogenous (produced in the body) growth factors are used as cosmeceuticals. A cosmeceutical is a substance that exerts both cosmetic and therapeutic benefits.
Skin creams containing a physiologically balanced mixture of growth factors and other proteins are available to reverse the signs and symptoms of:
- intrinsic skin ageing mediated by the process of natural ageing
- extrinsic skin ageing mediated by environmental factors.
In intrinsic ageing:
- there is a programmed tendency for cells to stop proliferating or dividing
- the amount of collagen decreases in the skin over time (about 1% a year)
- the degradation of collagen increases so that overall, the dermis thins by 20% in the elderly
- in addition, elastic fibres become damaged causing laxity.
In extrinsic ageing, external factors are responsible, particularly ultraviolet radiation due to sun exposure. Extrinsic factors cause degradation of collagen as well as other key elements of the skin. This leads to:
- coarse wrinkling
- broken blood vessels
- skin laxity
- prominence of pores
- discolouration or uneven skin tone.
What are the effects of growth factors in skin creams?
Results from multiple controlled clinical studies have shown that the application of skin creams containing growth factors:
- reduces the appearance of fine lines and wrinkles as a result of new collagen synthesis
- improves the appearance of age spots and evens out pigmentation
- reduces skin roughness
- improves skin texture and elasticity
- improves skin smoothness and tightness.
What are the growth factors in commercially available skin creams?
Currently, there are several topical skin creams containing a single growth factor or multiple growth factors and cytokines (small protein molecules secreted by cells) available for sale over the counter. They may also contain soluble collagen, matrix proteins and antioxidants to neutralise free radicals. None of the products are FDA approved. They are available for sale over the counter.
|Transforming growth factor beta (TGF-B)||Stimulate collagen secretion|
|Vascular endothelial growth factor (VEGF)||Stimulate new blood vessel formation|
|Hepatocyte growth factor (HGF)||Stimulate new blood vessel formation|
|Keratinocyte growth factor (KGF)||Stimulate epithelial cell growth|
|Interleukins (IL-6, IL-7, IL-8)||Reduce inflammation|
|Basic fibroblast growth factor (bFGF)||Promote formation of new blood vessels|
|Insulin-like growth factor 1 (IGF1)||Promote cell growth and multiplication|
|Platelet-derived growth factor AA (PDGF-AA)||Regulate cell growth and division|
|Transforming growth factors (TGF-B2 and B3)||Stimulate collagen secretion|
|Granulocyte monocyte colony stimulating factor||Increase number of white blood cells|
How safe are skin creams containing human growth factors?
Human growth factors are messengers designed to be received or “heard” by specific receptor sites – the “ears” on the surface of skin cells. The main task of human growth factors is to cause cell division and multiplication. For example transforming growth factor (TGF) stimulates collagen production and epidermal growth factor stimulates skin-cell production.
Most of the research on human growth factors for skin has looked primarily at the issue of wound healing, and at short-term use. Much remains unknown at this time, especially in terms of long-term risk or stability, when growth factors are used in cosmetics and applied to skin. Well-controlled clinical studies are lacking.
Current concerns about using growth factors for cosmetic purposes include:
- In skin-care products, growth factors would be used repeatedly, and possibly over long periods of time.
- If they cause cells to over-proliferate, they might cause cancer or other health problems.
- In the case of TGF, which stimulates collagen production, it can encourage scarring, because scars are the result of excessive collagen production.
- It is not known whether growth factors contained in cosmeceuticals are stable, can be absorbed adequately, or exert a functionally significant outcome to induce dermal remodelling and reverse photoageing (wrinkles).