Episkin, developed by French, German and Swiss scientists, is being claimed as the most advanced laboratory-made skin in the world. It takes a relatively rapid 19 days to grow in a special solution and is reported to be a very good approximation of the architecture of human skin, with all its layers and constituents.
Grown from living tissues in culture, it apparently feels like real skin and can tan, display some features of ageing, show signs of irritation, and be manipulated to produce different colours.
Professor Michael Balls, a European Union-funded scientist and anti-vivisectionist (he holds a chair at Nottingham University), has called the man-manufactured skin "breathtaking and astounding".
It has both a dermis and epidermis, the thick inner and thin outer layer, respectively. During its cultivation, the skin culture is raised out of the solution and allowed to dry and harden, to mimic the tough outer layer of human skin. Beneath the layers lies a carpet of connective tissue and collagen.
The layers contain the three main cell types found in the epidermis - keratinocytes, which produce the keratin that lends skin its toughness; melanocytes, which produce the pigment melanin and are responsible for colour and tanning; and Langharans' cells, the sentry cells that look out for signs of distress to the skin and alert the immune system. It is the incorporation of this last type of cell - harvested from umbilical cords - that makes Episkin unique. The breakthrough lay in the special culture that was used to make the Langharans' cells "take".
It is hoped that it will replace painful (and always ultimately fatal) animal tests for skin creams, make-up, sun lotions, and new chemical compounds and ingredients. There are currently an estimated 30,000 cosmetic tests carried out on animals in Europe each year.
Episkin could also be used in skin grafts for burns victims. In such grafts a small piece of healthy skin is taken from a patient, then attached to the infected area, where it grows to eventually cover the wound. However, in severe injuries the patient may not be able to provide enough of his or her skin, so surgeons resort to using industrially made skin, known as epidermal sheets.
Professor Balls also reiterated what we have known for years about the value of experimenting on living skin cultures rather than animals:
But these replacements, which are made by culturing human skin cells taken from biopsies and from the discarded foreskins of circumcised infants, are quite crude. They do not contain all the cell types, such as those responsible for chemical sensitivity or pigment. This is a problem for both applications. The pigment of grafted skin often does not match the patients' own, which is not ideal cosmetically. And the lack of sensitivity means that existing substitutes cannot be used for chemical testing.
Episkin is also expected to be valuable in testing for allergies. This is because the Langharans' cells are responsible for informing the immune system that it is under siege (these cells start the chain of biological events that lead to skin rashes, for example). When an irritant is placed on the skin, it becomes inflamed. Even though Episkin does not have any blood vessels and so cannot turn red, it can release signalling molecules when it is under duress. The more distress signals released, the more of an irritant the chemical is judged to be.
The next research stage involves finding a way of keeping Episkin alive in the lab for longer than a month. Normally skin renews itself after this period, but because Episkin is not plumbed into blood vessels, it cannot replenish itself. Stem cells - those that have not specialised to build a particular part of the body - may provide an answer.
[Source: Sunday Times, 24.5.00; New Scientist, 18.12.99]
Meanwhile, for the first time in history, regulators in the United States have approved a full-scale replacement of an animal test. InVitro International's new synthetic skin test, Corrositex, can be used instead of rabbits to test the safety of thousands of new chemicals.
The in vitro test determines chemical corrosivity and permits the assignment of Packing Group classification for Class 8 corrosives. It is based upon a biomembrane and chemical detection system, which becomes coloured when exposed to potentially corrosive substances. Users simply record the time it takes for the sample to break through the membrane, then they can assign the relevant Packing Group classification, or use the data as a ranking tool or to substantiate marketing claims.
It replaces the rabbit test for dermal corrosivity by reliably mimicking this test (though clearly mimicking human skin reaction to corrosives would bring more reliable results). Corrositex can provide Packing Group determination in as little as 3 minutes and no-longer than 4 hours, whereas animal tests can take 2 to 4 weeks, and is also advertised as both more accurate and cost-effective.
The agreement by the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration, the Consumer Product Safety Commission to accept the test was welcomed by campaigners in the US and elsewhere. Since there are currently more than two thousand new chemicals tested on animals every year, the substitution of Corrositex will save thousands of rabbits' lives.
[Press release on website of InVItro International, 16632 Millikan Ave, Irvine, CA 92606; www.invitrointl.com]
Max Newton, Uncaged Campaigns 08.05.01