This is the kind of advertisement we might be seeing in the not too far distant future given the pace of scientific discovery involving these amazing cells. OK, so it’s not yet possible to go out and buy a stem cell product you can rub on to (or inject into) your skin for guaranteed skin renewal, but the more we find out about how these miraculous little units work, the closer that day comes.
Have you ever wondered how it is that hair is constantly being born, falling out and dying only to be replaced by yet more hair? Or how you cut yourself and a few days later your skin is intact again? That, my friend, is all down to stem cells. Let’s dig a bit deeper.
Getting Under the Skin with Stem Cells
Did you know that the skin contains around 20 different types of cell? It’s not surprising when you realize what a complex organ it really is. We often focus so much on one of the skin’s functions (i.e. how good it makes us look to other people) that we forget that it also protects us from cuts, scrapes, bugs and UV radiation; keeps us at the right temperature and ensures we don’t dry out. Oh, and there’s also the small matter of connecting us with our environment by sensing changes in temperature and pressure.
Scattered throughout the skin are three – or maybe even four – types of stem cell, but they all have different functions and some are more easily found than others.
Three Types of Stem Cell
The skin is divided into three layers and the outer layer, the epidermis, is itself layered up. Top of the pile is the stratum corneum which is basically dead and gradually flakes away with the hustle and bustle of daily life. The real magic happens within the deepest layer of the ectoderm – the basal layer. This is a hive of activity and is where we find epidermal skin cells which generate keratinocytes, the most common type of cell forming the epiderm. Epidermal stem cells can create the precise type of cell they need without changing themselves – this is the miracle behind all stem cells and which is why scientists are pretty excited about finding them and getting them to do what they want.
Deeper still and we enter the dermis which contains the roots of our hair follicles, sweat glands and oil (sebaceous) glands. The intricacy of these structures require a powerful type of stem cell – one that can become a wide range of daughter cells – and these have been found within the hair follicles, mostly concentrated in an area called the bulge. These are now known to be able to travel to the surface of the skin and help in wound repair so are of particular interest to researchers.
Then we come to grayer areas of knowledge. Melanocytes are known to be present in the skin but are hard to pin down. These stem cells regenerate pigment-forming cells so could one day come in useful for treating skin pigment disorders. As for mesenchymal stem cells (MSCs): there is evidence to show that these are present in the skin but some scientists are unconvinced. Why does it matter? Because MSCs are the most abundant and easily harvested source of adult stem cells and form the basis of almost every experimental stem cell treatment available today. Put simply, if MSCs are indeed present and active in the skin, patients with skin disorders could theoretically benefit from stem cell treatment today rather than decades down the line.
Current Skin Stem Cell Treatment Options
Thanks to professor Howard Green’s work in the 1970s, stem cells from the skin are now used in skin graft treatments but only for severe skin damage, such as third degree burns, and only via a small number of licensed treatment centers. Any stem cell products which require laboratory cultivation or genetic manipulation require stringent safety and efficacy testing before they can be licensed, so most potential stem cell treatment options remain just that – potential.
However, as mentioned above, MSCs harvested from a patient and returned to that same patient with minimal processing can be used for treating patients providing the medical staff, equipment and premises used are licensed. Due to their abundance, MSCs can be quickly and safely cultivated in a closed system and returned to the patient’s body. MSCs can produce many different types of cell and are known to migrate to the source of wounds to assist in tissue regeneration. Most pioneering stem cell treatments are part of experimental studies aimed at finding more about exactly how MSCs work.
The future is on its way
It is already possible to grow new skin using stem cells but there is a long way to go. Stem cells require instructions, via a complex mixture of chemicals, to become exactly the right type of cell. In some cases, for example genetic skin diseases, specific genes may need to be identified and inserted or removed from cells. Then there is the challenge of getting it all to work inside a human being. So far, skin grafting has shown it is possible to use stem cells in tissue regeneration but the result is far from perfect (e.g. skin grafts contain no hair follicles or glands). However, every new discovery brings us that bit closer to unlocking the full power of stem cells and harnessing them to renew our skin at its deepest level.
courtesy: Dr Hazem Barmada/myskin.com