Stem cells in skincare products – should we believe the hype? Dr Haran Sivapalan takes a look at the science behind the claims.
Ever wonder how a single cell, formed when a sperm fuses with an egg, manages to grow into a fully formed human, replete with a muscular, beating heart, a brain full of nerve cells and cased in skin and hair? How does an embryo, made of just a few identical cells, eventually give rise to such a wide variety of tissue types?
The answer lies in stem cells. But you won’t find these ‘human embryonic stem cells’ in your skin cream. So, when, for example, a facial mask states it contains ‘stem-cells,’ are we dealing with a branding error, a clever marketing ploy, or is it state-of-the-art science? Let’s take a look.
What are stem cells?
Stem cells are living cells which have the ability to become other types of cells. All organisms that have more than one type of cell – like plants and animals – have them including. Through a process known as ‘differentiation’, stem cells can turn into other cells with specialised functions – e.g. blood cells which transport oxygen, nerve cells which conduct electrical impulses or leaf cells which make sugars for plants.
Apart from being able to turn into whatever type of cell is needed, they have another trick which makes them ideal for the skincare business – they’re ‘self renewing.’ Unlike regular cells, which can only divide between 40 and 60 times before dying, stem cells can divide and replicate themselves an unlimited amount of times – a key to eternal youth.
Initially stem cells are “totipotent” – that is, they have the potential to develop into any type of cell needed to create a whole organism. For example, a fertilised human egg (or ‘zygote’) has the ability to generate an entire human. Similarly, stem cells in a plant zygote can generate, as an example, a whole tree.
As the organism develops though these cells become more specialised and can only develop into specific types of cells. At this stage they’re known as ‘multipotent’ and this is what happens by the time the cells transform into the layers that form your skin.
Stem cells in the skin
As the outer layer of skin (epidermis) is damaged from everyday physical forces, exposure to sunlight and exposure to chemicals, it needs to be constantly renewed and regenerated. And, if you sustain a cut or wound, the skin needs to heal. Fortunately, the bottom or ‘basal’ layer of the epidermis contains these multipotent stem cells that can regenerate new skin cells and promote wound healing. These epidermal stem cells make up between 2 and 7% of all cells in the basal layer.
Hair follicles also have multipotent stem cells. They not only create the cells for new hairs, but also for sebaceous glands and other cells in the epidermis. These stem cells are concentrated in an area at the bottom of the hair follicle called the ‘bulge region’.
So the question arises: If stem cells ordinarily replenish cells in the skin then, could they be externally applied to rejuvenate the skin and counteract ageing, by creating new skin cells?
Today the shelves are packed with skincare products that “contain stem cells” and purport to have rejuvenating and anti-ageing effects. Consumers apply these products to their faces and body in the hope of gaining more youthful skin.
Unfortunately, there is no evidence to support such claims. Moreover, the practice of putting these types of cells in skincare products is massively scientifically flawed from the outset.
Stem cells in the skincare products
First things first: the ‘stem cells’ in skincare products are from plants. They do not come from human embryos or from adult human skin or from any other animal. When you consider that a multipotent plant stem cell is designed to generate roots, shoots and leaves etc. – it isn’t obvious how plant stem cells would generate new human skin cells.
This point becomes moot, however, given that these cells need to first of all be living in order to create new cells and have any ‘rejuvenating’ effect on the skin. The plant cells in creams and lotions, denuded of a supportive network of other cells, nutrients and optimum temperature conditions, are not living. They are dead. And, as such, they cannot generate new skin cells.
In addition, when a cosmetic product says it contains stem cells, it means it contains the extracts of plant stem cells. But extracts, while not comprised of intact, living stem cells, could still contain active substances that help the skin. But, is it at all possible that these active substances could have an anti-ageing effect, perhaps by stimulating the human epidermal and hair follicle stem cells that already exist in our skin?
A small, in-vitro study looked at the effect of adding the extract of live plant stem cells from the Swiss Spätlauber apple tree to a culture of human stem cells from umbilical cord blood in a laboratory. The results showed that the growth of human stem cells increased and that the human stem cells were more resistant to damage from UV light – which is a positive thing as damage from the sun’s rays is a major factor in premature skin aging.
But, this was a very small study, conducted on cells in a dish under laboratory conditions – which is remarkably different to that of applying a cream to your skin. The results, while positive, are preliminary and much more research is needed.
Take home message
While you may have heard of stem cells being used to grow human skin (on studies in mice and other animals) as a potential treatment for burns, it is important to consider some key differences:
- The stem cells used are from humans (human embryonic stem cells)
- The stem cells are living cells
- The stem cells have been injected directly into the skin, not applied topically.
By contrast, the stem cells in cosmetic products are from plants, are not living (but rather extracts) and, crucially, do not directly cause the regeneration of skin cells. Overall then, skincare products containing stem cells are, all other things being equal, no better than those products without them – don’t believe the hype.