Scientists have developed a lab grown epidermal equivalent from stem cells that possesses properties similar to those of normal human skin, which they hope could eventually be used as both a tool for studying skin disorders and a potential replacement for animal models in pharmaceutical and cosmetic testing. The results have been published in Stem Cell Reports.

The epidermis is the outer layer of skin whose primary function is to form a protective semi-permeable barrier. This barrier not only stops things getting in like potentially harmful microbes, but it also prevents unregulated water loss. The generation of lab grown epidermis, or human epidermal equivalents (HEEs), is desirable in order to discern the mechanisms of particular skin disorders. Not only that, they may also have applications in the development and screening of drugs.

Although HEEs have been engineered previously they have been limited in their use since they did not form fully developed epidermal barriers. The number of HEEs that could be developed from a single skin biopsy was also insufficient. In this new study, scientists from King’s College London and the San Francisco Veteran Affairs Medical Center turned to stem cells in order to attempt to address these problems.

The scientists used two types of stem cells- human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), both of which are capable of infinite proliferation and therefore provide a potentially unlimited supply of genetically identical cells.  

The team differentiated the stem cells into keratinocytes (the predominant cell type found in the epidermis) which were very similar to those isolated from the biopsies. They then used these to generate HEEs, which they discovered possessed functional permeability barriers akin to those found on human skin since they were able to block water permeation.

The team hope that this can be scaled up for eventual use in asthetic and regenerative medicine, and also potentially as a cost-effective in vitro model for drug development and cosmetic testing.

Lead researcher of the study, Dr Dusko Ilic, said in a press-release “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 conditions and sensitivities in different populations.”