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Cultured tissue replaces laboratory animals

Bart De Wever has worked in the field of human skin culture for many years. Not for transplantation, but as a means of testing the effects of cosmetic products. De Wever explains: ‘There is a real need for alternatives. First and foremost, there is, of course, the suffering inflicted on so many laboratory rabbits. However, we are also facing another problem. The skin and cornea of the rabbit differ considerably from those of humans and therefore do not always accurately predict the way in which a human will respond. Clearly, it is high time to use an alternative.’

De Wever has developed a method for culturing skin, corneal tissue and oral mucous membrane tissue. ‘Tissue cultured “in vitro” (in an artificial environment) is a very good alternative. It is an excellent way of testing the toxicity and effectiveness of products.’ How does De Wever go about this process? ‘We take cells from human tissue – from skin that is removed during a surgical procedure, for example. We isolate the individual cells from the tissue and then put them into small plastic beakers that have a permeable membrane in their base. The cells are fed by this membrane and start to grow. After about two weeks, tissue – in this case, skin – has formed. We then expose the cultures to the air. Under these natural conditions the cells mature, and well-keratinized skin or a strong cornea forms.’

Does this mean that, within a few years, laboratory rabbits will no longer be needed? De Wever: ‘We are still at the pre-validation stage, in which we have shown that the results from our models are comparable to those from the animal model.’ To facilitate this process, De Wever chose twenty substances that had already been tested on rabbits. Based on the results of these rabbit tests, ten of these substances had been classified as non-irritants, and ten others as either mild or strong irritants. ‘We applied these substances to the cultured corneal tissues and studied the reaction. The traditional Draize Test measures the degree of redness of the rabbit’s eye and observes how long it takes for the redness to disappear. The substances that cause redness in normal skin or corneal tissue are called cytokines. The cultured tissue also produces cytokines, and we are able to measure these. Cells will die. If the rate of cell death is low, this means that a substance is not a strong irritant. And if cell death is high, the opposite is true.’

However, De Wever was not completely satisfied. He went on to test his results by using the same number of substances in comparable tests on cows’ eyes (obtained from a slaughterhouse) and snails. ‘Our findings were confirmed once again by the results. We demonstrated that ten of the chosen substances were irritants. But our tests showed that three of the ten substances that were not actually classified as such, were, in fact, irritants.’ This was confirmed by hospital data obtained from people who had experienced problems after getting one of these three substances in their eyes. Our findings were confirmed from all sides. ‘It’s cause for concern that the information on toxicity contained in data banks is based on rabbit tests and indicates that these three substances are completely harmless. In actual fact, it has been shown that they do cause irritation.’ For further confirmation of his results, De Wever carried out his experiments in the laboratories of no less than four large pharmaceutical companies. The results were repeated in every laboratory, which proves that De Wever’s in vitro test is reproducible. The same cannot be said of the Draize Test. ‘At one time, three substances were tested on rabbits in 24 different laboratories. Every laboratory came up with different results. Clearly, they were not reproducible.’

Professor Frans Ramaekers – a professor in Molecular Cell Biology and De Wever’s supervisor – organized a small symposium on the occasion of De Wever’s Ph.D. thesis defence. ‘At this symposium, internationally renowned scientists exchanged views on alternatives to animal experimentation. Representatives of the pharmaceutical industry showed a great deal of interest as well. De Wever’s research is also of great importance to this group. From 2009, cosmetic products that have been tested on animals may no longer be sold within the European Union. As a result, the hunt for alternatives is in full swing. Both from an economic and from a political point of view, Bart De Wever’s research is attracting a great deal of interest.’

Throughout Europe, De Wever’s alternative is seen as important for the near future. Bart De Wever says: ‘The European Commission is shortly planning to test the toxicity of 30,000 commonly used chemical substances because there is not enough toxicological data on them. There is a real need for a data bank. It is estimated that this research will entail four million animal experiments and will cost €2.5 billion. Putting aside the question of capacity, I should point out that, even if all the laboratories in Europe were to work on this full time, the research wouldn’t be finished until 2057. The decision has now been made to test the most commonly used substances first.’

Bart De Wever is critical of the so-called toxicology bibles. ‘Government employees take these “bibles” too literally and accept them unquestioningly. Even worse, people who question them are considered to be nuisances. But the fact of the matter is that you cannot always satisfactorily compare animal experiments with the human situation.’ Unfortunately, it could be another ten years before the alternatives are validated. ‘But at least we are on the right road,’ says Bart De Wever. ‘Three of the largest pharmaceutical companies in the world have supported my doctoral research. The cosmetic industry is almost certainly going to adopt this animal-friendly and cheap method.’

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