A novel and first of its kind discovery may have altered the way we test products and compounds meant for human use, reveals a study produced and internationally led by the United Kingdom’s King’s College London and the San Francisco Veteran Affairs Medical Centre in the United States.
For the first time ever, scientists have been able to create a laboratory-grown epidermis, or outer layer of the skin, thanks to stem cells, with a functional permeability barrier allowing it to respond like real human tissue.
The study was published in the scientific journal Stem Cell Reports, available to be read online.
The epidermis essentially acts as a barrier to the outside world, protecting the body from pathogens, whilst also regulating the amount of water leaving the body. Interestingly, this outermost layer of skin is avascular, meaning it derives its oxygen via diffusion from the outside air, unlike other tissues which require a blood flow for gaseous exchange of oxygen and the byproduct carbon dioxide.
The findings by the international team are particularly relevant seeing as science is yet to create a viable model for testing the barrier function, reports the paper, particularly due to the fact that previous attempts were unable to replicate the fully developed epidermal barrier.
However, with the help of stem cell research, the team were able to create human epidermal equivalents (HEEs), which could produce an unlimited number of keratinocytes (the cells that make up the skin).
In order to create these laboratory-grown specimens, the scientists used two types of stem cells: human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), the latter being generated form adult human cells.
Importantly, these stem cells allow the researchers the possibility to create the aforementioned unlimited number of skin cells, which science had yet to achieve, as they are capable of increasing the number of cells ad infinitum, whilst allowing their genetic material to be fully decrypted. This is particularly important as some cells may contain genetic differences that influences the nature of epidermal growth and development, which would result in an altered cell sample or one that may differ from human skin.
Importantly, when the researchers compared the skin created by the stem cells, they noticed the structural and functional properties of their creation were the same as that of normal human skin.
These properties now allow scientist to study the skin in the lab, with wide ranging benefits.
Typically, trials often involve animal testing, in order to assess the compatibility of products before they enter human testing phases. Naturally, this form of testing raises ethical arguments, and some members of the public would like to see it halted.
Thus, the production of a laboratory-grown skin that acts in a similar way to our very own tissue, would bypass the need to use animals in the testing phase of clinical trials.
In addition, understanding how the skin develops in the lab could allow scientists to better understand conditions whereby the skin’s genetic material differs from the norm, such as in cases of ichthyosis or dermatitis, said Dr Theodora Mauro, leader of the American team, speaking during the news release of the findings on Eureka Alert!.
Dr. Dusko Illic, team leader for the King’s College group and also speaking for the Eureka Alert! press release, underlined the wide ranging applications of his team’s work: “Our new method can be used to grow much greater quantities of lab-grown human epidermal equivalents, and thus could be scaled up for commercial testing of drugs and cosmetics. Human epidermal equivalents representing different types of skin could also be grown, depending on the source of the stem cells used, and could thus be tailored to study a range of skin conditions and sensitivities in different populations”.
What other applications would you like to see stem cell research used?