Written by Emily Locke
The thalidomide tragedy, one of the most notorious drug scandals in Germany, affected around 10,000 people. Thalidomide was a sleeping pill and tranquillizer marketed under the trade name Contergan [1]. It was also taken by many women to treat typical morning sickness during pregnancy and was considered particularly safe in terms of side effects. However, the use of thalidomide led to an increase in severe malformations or even the absence of limbs and organs in newborns [2]. In November 1961 - after 300 million pills had already been sold - it became known that the active ingredient thalidomide could cause severe damage to fetal growth. Today, there are still around 2,200 thalidomide victims living in Germany, who suffer more and more from their physical limitations as they get older [1].
How could something like this happen? Of course, new active ingredients are extensively tested before they are approved in order to detect undesirable effects and assess possible risks. As standard, these safety tests also include animal experiments to test the drug's mode of action and tolerability. Thalidomide was also tested on animals before it was approved for the market, but the damage that the drug caused to human embryos in the first weeks of pregnancy was not detected in these tests [3]. It is unclear whether tests were also carried out on pregnant animals, as all test protocols of the manufacturer Grünenthal were destroyed [4, 5]. Interestingly, the thalidomide scandal serves as an argument for both opponents and supporters of animal testing. Opponents see the scandal as proof that animal testing offers no safety and that the results cannot be transferred to humans [5]. Proponents, on the other hand, argue that the catastrophe could have been avoided with preclinical animal testing on a much larger scale, i.e., with additional tests on pregnant animals of different species [6].
Regardless of which side may be right about the thalidomide scandal, the use of animals for research purposes has always been a critically debated topic. Is it ethically justifiable to carry out experiments on animals? How meaningful are the results obtained from animal testing? What alternative methods are currently available? And to what extent could they replace animal experiments in the near future? In this article, we present different views for and against animal testing and show possible ways in which their number could be reduced in the future.
These topics await you:
1) Animals in Research – Current Statistics from Germany
2) “Animal Testing is Torture!” – What Opponents of Animal Testing say
3) Are Animal Experiments “essential”? – What Proponents of Animal Testing say
4) In vitro and in silico instead of in vivo – Alternatives to Animal Testing
5) Animal-Free and Life Science Products
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Animals in Research – Current Statistics from Germany
Animal testing is conducted for various purposes, including the study of physiological processes, the development of products and therapies, and the verification of product safety [7]. Each animal experiment must be applied for at the relevant approval authority according to the German Animal Protection Act (TierSchG) [8]. In Germany, approximately 2.44 million animals were used for scientific purposes in 2022, of which 1.73 million animals were used alive and sometimes multiple times in experiments, while an additional 712,000 were killed without prior interventions to use their organs or tissues for research purposes [9]. More than half of all animal tests in 2022 were done for basic biological research, 16% were attributed to the manufacture, approval, or control of products, and 14% were for applied research [10].
When examining the distribution of animals used in experiments, rodents (79%) are by far the most commonly used, followed by fish (12%). The proportion of mice is particularly high at 72%. This is partly due to the simple husbandry conditions, short generation times, increased use of transgenic mice, and complete genome sequencing.
Experiments on "higher" vertebrates or mammals are much rarer: in 2022, 2,267 primates, 2,877 dogs, and 538 cats were used in animal testing [10]. The background is the widespread belief that "higher" vertebrate species suffer more from experimental procedures than "lower" species. The EU Directive 2010/63/EU on the protection of animals used for scientific purposes therefore places primates and other animal species under special protection. For example, the use of great apes (gorillas, orangutans, chimpanzees, and bonobos) in animal experiments has been strictly prohibited in the EU since 2010. However, the postulated hierarchy of suffering between "higher" and "lower" species under given experimental conditions is scientifically questionable and is viewed as controversial from an ethical perspective [8].
“Animal Testing is Torture!” – What Opponents of Animal Testing say
The central ethical question surrounding animal testing is whether and to what extent human benefit justifies animal suffering and death [7]. Essentially, it is about the status given to animals in relation to humans. Opponents of animal testing argue that animals, as sentient beings, deserve morally equivalent treatment to humans and that therefore killing animals and inflicting pain is morally unacceptable. Animals are degraded to instruments of measurement in experiments, which does not correspond to the dignity of the living being [11].
Figure 1: Many people take to the streets against animal testing and for increased animal protection. For instance, in 2015, nearly 2,500 people demonstrated in Berlin under the motto “Research yes – Animal Testing no!” for animal-free research [12] (AI-generated image).
In addition to ethical arguments, many critics see a problem in the validity of findings obtained from animal studies. They argue that these results cannot be transferred to humans and are thus mostly useless. It is questionable whether different species (such as humans and mice) react the same way to substances due to the structural and functional similarities of many organs. Instead, the mechanisms of action of substances in the organism are more species-specific [7]. The aforementioned thalidomide scandal is often cited as an example where researchers were misled about product safety – from the point of view of opponents of animal testing due to the lack of significance of animal experiments.
Are Animal Experiments “essential”? – What Proponents of Animal Testing say
Proponents of animal testing hold a completely different view – or those who consider animal testing to be essential. They believe that the use of animals for scientific purposes is ethically justifiable when the expected scientific gains justify the stress placed on the animals in the experiment [8]. It is therefore assumed that human interests, particularly in maintaining health, are fundamentally more valuable than the protection of other living beings. Moreover, proponents of animal testing point out that it would be ethically unacceptable to conduct clinical studies and other experiments on humans without prior animal testing if it were possible to at least estimate the risks associated with the study for test subjects through previous animal experiments [11].
Representatives of animal-based research also argue that all major findings in the field of medicine are attributable to animal testing. For example, the development of vaccines and the investigation of various pathogens have only been possible through animal trials, and a waiver of these would mean “slowing down medical progress and significantly diminishing chances of healing for sick individuals,” according to the German Research Foundation [11]. The transferability of results from animals to humans is possible due to the great similarities in cell and organ functions, particularly when considering species-specific characteristics. Some researchers believe that the complexity of an intact organism is necessary to examine all effects of a substance, especially when investigating the complex interplay of multiple organ systems [7]. So, does this mean that animal testing cannot be completely replaced in the future?
In vitro and in silico instead of in vivo – Alternatives to Animal Testing
In recent years, intensive research has been conducted on alternative methods to reduce the necessity of animal testing. This follows a key ethical guideline of animal research, known as the 3R principle: Reduction, Refinement, and Replacement. According to this principle, animal tests may only be carried out “when there are no other suitable methods available to answer the scientific question and the number and burden of the animals used are limited to the essential minimum” [8].
Figure 2: The logo of the British Union for the Abolition of Vivisection (BUAV). This is an internationally recognized symbol for cruelty-free products. In particular, many cosmetic products in Europe that have not been tested on animals bear this symbol [13].
Alternative techniques that can replace animal testing for many questions include in vitro methods using cell cultures and microorganisms [11]. Furthermore, there are increasing advancements in the field of organoids, i.e., artificially created cells of various tissue types, which play an increasingly important role as a promising replacement model [7]. In addition to in vitro methods, in silico tests are also being carried out today. For example, drugs can be developed on computers and their effects predicted in simulations [11]. It remains controversial to what extent these methods can replace animal testing in the near future, but at least for cosmetic research, a complete replacement of safety testing on animals by alternative testing methods is planned [7].
Animal-Free and Life Science Products
In addition to the experiments themselves, animals are also used in the production of life science products, for example, to produce substances such as growth factors that are still used for cell culture procedures or to produce antibodies for research and diagnostics. However, a shift is currently underway in this area as well, with more and more manufacturers committing to sustainable animal protection by developing products that are animal-free.
At Biomol, we are proud to collaborate with partners who focus on the topic of “animal-free”. For instance, our supplier ForMedium offers animal-free culture media for the growth of E. coli, where tryptone is replaced with soy peptone. InVitria uses plants as production hosts to offer safe and effective alternatives to serum and serum proteins. One of our newest manufacturers - Pacific Coast Biologics - provides state-of-the-art non-animal alternatives to cytokines, growth factors and other recombinant proteins, supporting ethical and sustainable research. And our partner AdipoGen Life Sciences has developed recombinant fusion proteins, called InVivoKines™, which are produced under animal-free conditions.
The reduction and replacement of animal testing while maintaining scientific progress remains a major goal in research. With the (further) development of many alternative methods and products, we are already getting closer to this goal. As researchers and members of the life science community, it is up to you and us: whenever possible, use animal-free products in the laboratory or switch to alternative methods to animal testing. Together, we can pave the way towards increasingly animal-free research!
Sources
[1] https://www.contergan-skandal.de/de-de/der-contergan-skandal, 25.09.2024
[2] https://de.wikipedia.org/wiki/Contergan-Skandal, 25.09.2024
[3] https://naturwissenschaften.ch/animal-experimentation-explained/relevance/security, 25.09.2024
[4] https://www.aerzte-gegen-tierversuche.de/de/wissenschaftliche-studien/contergan, 25.09.2024
[5] https://www.peta.de/neuigkeiten/contergan-spricht-der-skandal-fuer-oder-gegen-tierversuche/, 25.09.2024
[6] https://www.aerzteblatt.de/archiv/79061/Tierversuche-Das-Beispiel-Contergan, 25.09.2024
[7] Deutsches Referenzzentrum für Ethik in den Biowissenschaften (2024): Im Blickpunkt: Tierversuche in der Forschung. https://www.drze.de/de/forschung-publikationen/im-blickpunkt/tierversuche-in-der-forschung, 25.09.2024
[8] Deutsche Forschungsgemeinschaft (2019): Tierversuche in der Forschung: Das 3R-Prinzip und die Aussagekraft wissenschaftlicher Forschung. https://www.dfg.de/resource/blob/309210/f6c41e7837a3936896dad950a83c0e32/handreichung-sk-tierversuche-data.pdf, 25.09.2024
[9] Deutsches Zentrum zum Schutz von Versuchstieren: Verwendung von Versuchstieren im Berichtsjahr 2022. https://www.bf3r.de/de/verwendung_von_versuchstieren_im_jahr_2022-313306.html, 25.09.2024
[10] https://www.tierschutzbund.de/tiere-themen/tierversuche/statistik-zu-tierversuchen, 25.09.2024
[11] https://de.wikipedia.org/wiki/Tierversuch, 25.09.2024
[12] https://www.duunddastier.de/ausgabe/2500-menschen-gehen-auf-die-strasse/, 25.09.2024
[13] https://de.wikipedia.org/wiki/Datei:Buav.svg, 25.09.2024
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