Stretched taut across the top of a vial, the thin cream-coloured material feels almost like rubber. Barely 1 centimetre in diameter, this is a sample of Episkin 鈥� a reconstructed human skin which has been approved for testing if cosmetics are likely to irritate the skin. It is the first complete replacement for animal testing.
Although cosmetics and skincare giant L鈥橭r茅al has been developing reconstructed skin since the 1980s, the search for animal alternatives became urgent in recent months with the introduction of two pieces of legislation. In December 2006, the European Union introduced REACH, which calls for more than 10,000 chemicals used in cosmetics to be tested for skin irritancy by 2019. At the same time, the EU鈥檚 cosmetics directive bans the use of animals in such tests from 2009. 鈥淓urope is in conflict with itself, calling for both a decrease in animal testing and for significantly more products to be tested,鈥� says Estelle Tessonneaud, who developed Episkin with her colleagues at L鈥橭r茅al鈥檚 labs in Lyon, France. 鈥淧eople don鈥檛 have any choice but to adopt alternative methods.鈥�
Tessonneaud鈥檚 team grows the skin layers on collagen, using skin cells called keratinocytes left-over from breast surgery (see Diagram). The team can test the safety of cosmetics by simply smothering the skin in the product. They can then check the proportion of cells that have been killed off by adding a yellow chemical called MTT which turns blue in the presence of living tissue. 鈥淭o be validated we had to show that we could reproduce results as effectively as animal tests,鈥� says Patricia Pineau, scientific director at L鈥橭r茅al. Independent tests showed that in some cases Episkin was able to predict more accurately how a person would react to products than animal tests, she says.
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Episkin improves on animal testing in other ways too. For example, it can be adapted to resemble older skin by exposing it to high concentrations of UV light. Adding melanocytes also results in skin that can tan, and by using donor cells from women of different ethnicities, the team has created a spectrum of skin colours which they are using to measure the efficiency of sunblock for different skin tones.
鈥淭his is a great advance 鈥� not just for animals but for people, who will finally have a safety test that is relevant to them,鈥� says Kathy Archibald of the anti-vivisection group Europeans for Medical Progress, London. She says animal skin often differs dramatically from human skin in terms of sensitivity.
鈥淭his a great advance, not just for animals but for people who will finally have a cosmetics safety test that is relevant to them鈥�
Chris Flower of the Cosmetic Toiletry and Perfumery Association in London also welcomes the move. 鈥淭he fact that it has taken 20 years of research to come to this point shows just how difficult it is to replace animal testing,鈥� he says. 鈥淣ow it has been validated it can potentially be applied, not only to testing new shampoos and cosmetics, but more widely, in medical research.鈥�
L鈥橭r茅al already has a skin to help study a rare genetic disease that affects so-called 鈥渕oon children鈥� who are hyper-sensitive to sunlight (Photochemistry and Photobiology, January 2005, ). Tessonneaud and her colleagues are also working on a skin substitute for treating major burns and ulcerations.
Tissue scaffolds can replace knockout mice
Genetically modified animals play a huge role in helping researchers to understand the role of specific genes in human disease. Now, Paul Genever at the University of York, UK, and his colleagues are developing an alternative based on human tissue, that could cut the number of animals used in research.
The team has already grown a 3D 鈥渢issue scaffold鈥� from mesenchymal stem cells taken from human bone marrow, and is now trying to 鈥渒nock out鈥� individual genes in the stem cells, enabling them to discover the precise roles the missing genes play. Genever鈥檚 team is just one of those to receive a grant from non-animal medical research charity the , in Hitchin, UK. Another team, led by Rachel Tribe at King鈥檚 College London, is attempting to silence genes in human uterine tissue, to better understand why premature labour occurs. 鈥淜nockout mice are currently used for this, but mice can give birth to 14 babies at a time, so they aren鈥檛 a very good model for human pregnancy,鈥� says Tribe.
Sophie Petit-Zeman of the says that any advance that helps reduce the number of animals needed in research is to be welcomed, although researchers will still need to confirm their results in a whole animal.
