For years, the development of new medicines, pesticides and chemicals went hand in hand with animal testing. But that time seems to be over. Walter Westerink, section leader of the Flexible Innovation Team at Charles River Laboratories, is working on test methods that replace laboratory animals. “For some applications, lab models with human cells are now more reliable than animal testing.”
Charles River is an international research company that tests chemical and pharmaceutical products for safety. The branch in Den Bosch focuses mainly on industrial chemicals. “For years, a lot of animal testing was done there,” says Westerink. “But there is a clear shift going on. On the one hand, for ethical reasons, but certainly also from a practical and scientific necessity.”
The latter is certainly true for the well-known Draize test, in which a substance is dripped into a rabbit's eye to see if irritation occurs. "With mild reactions, the tests sometimes give varying results, depending on who does the test and how it is interpreted," says Westerink. "Then we see that in vitro models - tests on cultured human cells - are actually more consistent."
Human skin
One of the most widely used alternatives are so-called 3D skin models. These consist of human skin cells that are built up in layers to a structure that closely resembles real skin. “We do not develop these models ourselves, but purchase them from specialized companies,” says Westerink. “They imitate human skin surprisingly well.”
For some applications, the lab also uses real human skin tissue that is released during medical procedures, such as tummy tucks. For eye tests, it uses slaughterhouse waste from calves. “As long as we don’t have to use extra animals and we do get reliable results, that’s a win.”
Combination of tests
According to Westerink, animal testing is often unnecessary for relatively simple tests, such as skin or eye irritation. “The artificial skin model works very well for skin tests. Animal skin, such as that of rabbits, contains many hair follicles and is more porous. As a result, rabbits sometimes react more strongly to substances than humans. With a human model, you get a more realistic picture.”
However, there are still plenty of challenges. Some effects are harder to imitate, such as allergies, hormone disruptions or damage to unborn children. “For allergies, we combine different tests: a chemical test, a test with human immune cells, skin cells and a computer model. Only if these together do not provide a definitive answer, an animal test may be necessary.”
Validation
Although science is advancing, the acceptance of these new test methods sometimes stagnates with the legislator. Westerink: “A test must be validated before it can be used legally. That process can take four to ten years. And even if the test is ready, there still has to be someone at the authority who has the time and capacity to approve it. That bottleneck is now really in the assessment.”
To trust
Yet the movement towards animal-free science is in full swing. New technologies such as organ-on-a-chip – where human cells on a chip mimic mini-organs and – toxicogenomics – which examines gene activity under the influence of substances – are making more and more possible. Westerink and his team are also working on validating such methods. “We already work under strict quality systems, but are now also going for a new certification that is specifically aimed at in vitro research,” says Westerink. “In this way, we want to further increase confidence in these models.”
Want to know more? Walter Westerink is one of the speakers at the seminar From lab animal to lab model: animal-free future in the lab on Thursday 25 September during the LabNL trade fair. Discover which technologies are making a difference now and in the future – and see how the future of animal-free innovation is taking shape.
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