Stem Cells, Growth Factors and Cytokines

Stem Cells are immature cells that have the ability to renew themselves through miotoic cell devision for long term self renewal. They are not specialized but can differentiate into specialized cells. They act as a repair system for the body. There are two types of stem cells, embryonic and adult.

Stem cells can be harvested from bone marrow, blood, amniotic fluid, umbilical cord and placental tissue, teeth, skin graft, hair follicles, adipose tissue and bovine colostrum polypeptides. Using whole, live stem cells in shelved skin care products in not possible, they would not survive. Therefore, stem cells are cultured in a conditioned media in order to capture their bio-signals, growth factors and cytokines. No human DNA is present once they’re extracted.

The benefit of adding cytokines and growth factors to skin care products is that they facilitate regeneration, a process that slows as we age. They amplify cell to cell communication, stimulating pre-existing cells to a greater level of function. This amplification becomes beneficial when the wound healing cascade has been initiated by professional skin care treatments.

The leading stem cell sources used in anti-aging skin care products are from bone marrow and adipose tissue. Mesenchymal stem cells differ in there cytokine profiles. Some are inflammatory while some are not. Bone marrow stem cells have an anti-inflammatory cytokine profile associated with decreased levels of inflammatory cytokines TNF-a, IL-12, IFN-y, and IL-5 and increased levels of the anti-inflamtory cytokines IL-10 and IL-4, and actually secrete anti-inflammatory cytokines. Adipose stem cells are easier to harvest, thus having appeal. However, their ASC profile tends to be inflammatory. When used in the correct context, elevated levels of MMP’s can be beneficial for scar revision.

Bovine sourced colostrum polypeptides are another common source of growth factors in skin care products. Colosturm contains platelet-derived growth factor, transforming growth factors alpha, beta1 and 2, fibroblast growth factors, epidermal growth factors, and insulin-like growth factores I and III.

Growth factors cultured from recombinant growth factors or fibroblasts, not the sources mentioned above, are not as potent. EGF is a popular growth factor that relies on recombinant technology. Asking the manufacturer where their growth factors are sourced from, will give you an indication of the product’s potency and may sway you, or your clients ethical decisions.

Just like cytokines, some growth factors are inflammatory and while others are not. TGF-B1 and 2 (present in platelets) are inflmmaorty. TGF B-3 excreted by the keritinocyte are ant-inflamtory and released while microneedling. TGF B-3 also shuts off the inflammatory growth factors, TGF B1 and 2.

Also to note, growth factors don’t operate well in isolation. Many different growth factors combine to achieve tissue growth and repair. Products containing multiple recombinant growth factors are just beginning to come to market.

Plant stem cells do not have similar bio-signals as human stem cells do. Human cells have receptors on their surface to recognize human bio-signals. Human cells do not contain receptors for plant bio-signals. The benefit of using plant sourced ingredients would be for their antioxidant effect, or irritation causing endogenous stem cells to react. Any results obtained from plant stem cells cannot be attributed to increased cell to cell communication. Some plant stem cells have been genetically modified with human DNA to produce cytokines and growth factors. Weather these “new” stem cells fit the cell receptors of human cells, is unknown.

The bio signals stem cells secrete can have beneficial effects if properly sourced, cultured and prepared. Because growth factors are premindintaly responsible for orchestrating and regulating cellular function and repair after injury, it would make sense to include them after the wound healing cascade has been initiated.

In order for an ingredient (like stem cells) to be effective, we need to accurately attribute the result to the correct mechanism of action. When we understand how growth factors and cytokines work and what their purpose is in managing pathology, we can use them effectively.

References

https://stemcells.nih.gov/info/basics/1.htm

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2785020/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC303501/

https://www.tandfonline.com/doi/full/10.3109/15419061.2014.905930

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5674215/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3840479/

https://www.molbiolcell.org/doi/abs/10.1091/mbc.e02-02-0105