Tag Archives: animal models

Open Trials

Open Trials is a project led by Bad Science author Ben Goldacre that aims to form a complete collection of every clinical trial conducted around the world. A clinical trial is when a new medicine is tested in humans for the first time. The results from these trials are used to decide how well the medicine works and how safe it is. Currently, not all clinical trial results are published, especially when the findings are negative. This can have dangerous consequences on patient safety as medicine regulators and doctors may not be fully aware of a medicine’s effects. Therefore Open Trials is an important project.

However, before medicines are tested in humans for the first time, they are required to undergo pre-clinical tests in various species of non-human animals. These tests are required to show that the medicines are safe and effective in animal models before they are allowed to be tested in humans. However, the usefulness of these animal studies has been questioned because of the inherent biological differences between species. The results from animal studies are often very different from the results in humans, meaning that ineffective or unsafe medicines are given to humans in clinical trials. Conversely, potentially good medicines are rejected before they get to be trialed in humans because of poor results in animals.

What if we had an Open Trials–like project for pre-clinical animal studies, so that every animal study was recorded and all the results were openly available for others to review?

Here are some of the potential advantages of such a project:
– Overcoming issues such as publication bias. This occurs because studies with positive findings are more likely to be published leading to an unrepresentative and often misleading view of research that has been conducted.
– All data is given to regulators, so they can make a fully informed decision about whether a new medicine is allowed to be tested in humans.
– Finding out how useful and predictive the animal models are for human diseases and treatments.
– Reducing animal use by preventing duplication of animal studies, particularly ones with negative findings. If a study finds that a drug doesn’t work in mice, the results are unlikely to be published. Therefore other researchers might test the same drug again, without realising that it has already been proven ineffective.
Overall, more open reporting of all data can only be a good thing for science. Open trials is fantastic step forward, but more can be done for other types of experiments. This openness would be particularly valuable with animal studies due to the considerable ethical costs of the research.

The Use of Animals in Experiments — Not Because of Lack of Empathy?

Jolanta Zwolinska

The choice of an individual to use animals in experiments
is influenced by a wide range of social, religious and sometimes
career-driven factors, rather than a lack of empathy

Representatives of various religions and philosophical ideologies frequently make reference to the well known belief that one’s attitude toward the disabled, the sick, old people and children, is a measure of the humanity or moral value of the person. Yet, disputes arise when animals are included into the group of living beings entitled to the same type of consideration. The fact that they are used in scientific experiments is a highly controversial matter, and conflicting views are held by people both within and without the scientific community. This article presents a number of factors which might influence the decision of an individual to stand for or against animal use in experiments, including arguments voiced by representatives of the various sciences, both in support of or against the  continuation of animal experimentation.

Some historical and religious background

The approach adopted by ancient ethicists, in assuming  the dichotomy of human body and soul, resulted in man’s alienation from nature. Aristotle proclaimed a hierarchical structure of the world and the existence of essential differences between humans and animals, the latter being considered as inferior to the former. The intellect, according to that philosopher, was the main determinant of moral values.1 Adopted by the Judeo–Christian and Islamic traditions, the dogma of the immortal soul inherent in humans but not in animals, served to create a vast chasm between mankind and the animal world. Accordingly, Man rules over the world in which animals play an ancillary function.2–4 The cultures of Hinduism and Buddhism are based on the principles of respect for life and the protection of every living creature from suffering. Considered as being similar in their essence to humans, it is dictated in these religions that animals deserve to be protected and treated with reverence.3,5,6

Shaped throughout the ages, our stereotypical opinion of animals has been encoded into our collective consciousness, and cannot be easily overcome by newly emerging social concepts and ideas. For centuries, our attitude toward animals has been based on domination and power.4  In contemporary Christian culture, the majority of ethologists, psychologists and lawyers sympathise with an anthropocentric model of the biosphere, and take a negative stand with regard to animal rights. According to Bialocerkiewicz,5 animal rights reflect our attitude toward life and suffering and our appreciation of the universal principle of humanitarianism. Humans are not entitled to treat nature barbarically — i.e. to kill or mutilate, inflict pain or suffering. Bialocerkiewicz does not find any reason to recognise a unique role of mankind in the grand scheme of things, and emphasises a lack of religious, ethical or economic justification for awarding humans the right to take arbitrary decisions concerning the lives of other species.

The Catholic Church also acknowledges problems related to animal suffering. It speaks for an absolute ban on the mass breeding of animals and for the abandonment of procedures of animal testing used for cosmetics and various types of stimulants.7 According to Kozuchowski,8 a priest, it is our respect for ourselves and our claim to be perceived as more evolved beings that forbid us to treat animals as ordinary objects. A negative attitude toward animals is inevitably linked with a negative attitude toward other human beings.

The concept of ‘animal rights’ and morality

Cohen believes that rights result from contracts which are binding between members of a given community, and that rights, unavoidably, have inherently associated duties. Animals cannot undertake such obligations, and therefore they are not entitled to any rights in this sense (as cited in Mukerjee6). Guzek9 also points to the relativity of the concept of ‘animal rights’. He emphasises that rights can only be awarded to members of communities which are able to comply with commonly recognised ethical norms, so animals are not eligible to have such rights. Guzek believes that extremist activists of ‘animal right movements’ expect that animal rights should be similar
to, or identical to, human rights. Yet, evidence derived from observations shows that, whenever there is a conflict between animal rights and human interests, the latter always win. In Guzek’s opinion, human and animal rights are not, and cannot be, equal.9 Mukerjee, however, points out that children and mentally ill individuals cannot assume any obligations, nor do they comply with any norms, and yet they are not deprived of rights.6
According to Kotowska,4 the protection awarded to animals by the legal system of a given community depends on the attitude generally adopted by its members toward animals. If animals are treated as objects by the majority, then they will also be treated as objects by the adopted customary law, because there would, of course, be no one in such community to protest in their defence.
Many contemporary philosophers are reluctant to admit that it is pointless to extend our system of morality to include animals, opposing the claim that animal research does not constitute a moral problem. They emphasise the fact that speciesism is the cause of cruelty committed by man toward laboratory animals. Other philosophers take a less radical approach, accepting only some methods of animal use, and expressing favourable opinions about the banning of the most abusive research methods.6 Frey, a philosopher, emphasised that he was not an antivivisectionist, but that he accepted only those experiments with animals which yielded significant benefits and could also be conducted with human subjects.10 Singer, author of Animal Liberation,11 recognised by publicists as “the bible of the animal liberation movement”, believes that animal experimentation is acceptable only in the case of trial tests for life-saving drugs.

A contradiction in definition

The contradiction in the fact that people use animals as experimental models to acquire information pertaining to humans, and yet they refuse to acknowledge that animals have qualities recognised as human, is noted by Pisula.12 According to Griffin,13 the belief that no animal is capable of suffering or worthy of sympathy cannot be supported by any contemporary scientific evidence, and Spaemann14 emphasises that animals are not able to give meaning to, or control, their suffering. They are, indeed, doomed to suffer, in that it is particularly hard to endure, if they cannot respond to it with aggression or by escape. As a result of scientific progress, it is more and more difficult to justify the claim about the uniqueness of our species. Birmelin and Arzt, in their book, entitled Haben Tiere ein Bewusstsein [Do Animals Have Consciousness?],15 wrote: “…in terms of their mentality and emotions animals are more similar to us than we used to believe…”. What differs between us and animals, however, is not these qualities per se, but their intensity. Animals use senses which have become blunted in human beings. After long-term observations of social behaviour in elephants, zoologists assume that certain forms of morality and selfawareness may occur in more-highly evolved animals.16 Today, we also know that primates are able to experience emotions such as anger, fear, boredom, longing and loneliness.6

Opinions at the laboratory bench

It was emphasised by Mukerjee that scientists often decide to use animals, only if they are convinced that this is the only way to help people, and that sympathy for animals frequently affects this deliberation. Researchers try to reconcile the dictates of science with a humane approach — in fact, many of them love animals and volunteer to work for their benefit.6 Szyszko believes, however, that the choice of research method does not depend on sympathy for animals, or the need to acquire knowledge necessary for saving human health and life. Instead, it is proposed that senior academic staff members might sometimes encourage younger researchers to conduct animal experimentation, in order to contribute to the scientific accomplishments of the given institution.
As a result, animal experimentation is conducted all too often, and its purpose is not always justified by the needs of science. According to Szyszko, many higher-order animals suffer and die needlessly, frequently only to fulfil the excessive ambitions of young academics.17 In addition, Bialocerkiewicz highlights the fact that, in order to advance their careers and scientific outputs, some researchers are ready to carry out even the cruellest experiments, and gives an example of Baltimore, a physiologist awarded the Nobel Prize, who does not believe that “animal testing poses any moral problems”.5 As a result of such explicit approval by high-profile individuals, animals used in research can become perceived to be merely instruments — i.e. objects which can be exposed to any manner of tests.18 We see this in the fact that animals are often referred to as “experimental models”, “bioreactors”, or “source of replacement parts”, and this inevitably reinforces that idea that they have no rights and that they can be readily exposed to suffering and extermination.19 Feinberg insists that animals should not be treated as objects, although undoubtedly, they cannot be perceived in the same category as humans.20


Mukerjee points out that we are all morally responsible for the appropriately humane treatment of animals.6 The choice of an individual to use animals in experiments is influenced by a wide range of social, religious and sometimes career-driven factors, rather than a lack of empathy on the part of the researcher. Indeed, it is commendable that sensitivity to human pain and suffering defines the course of action for people professionally involved in medicine. What must be emphasised is that this sensitivity should be manifested as empathy for beings which are weaker and subordinate to humans, and the right choices should be made accordingly.
We should not make people suffer for the sake of animal welfare, but we also should not sentence animals to terrible suffering which leads to questionable benefits for people, not least in terms of the scientific validity of the results obtained. Due to progress in science, it is more and more difficult to justify the claim about uniqueness of our species, and being human is not only a privilege, but also an obligation to the creatures with which we share the Earth.

Jolanta Zwolińska
Faculty of Medicine
University of Rzeszów
E-mail: jolantazwolinska@op.pl


1 Serpell, J. (1996). In the Company of Animals: A Study of Human–Animal Relationships, 2nd revised edition, 316pp. Cambridge, UK: Cambridge University Press.
2 Tatarkiewicz, W. (2004). History of Philosophy, 21st edn, 376pp. Warsaw, Poland: PWN.
3 Lejman, J. (2006). Animal ethics in the light of the idea of sustainable development. Problemy Ekorozwoju 1, 99–105.
4 Kotowska, M. (2011). Selected aspects of animal protection
according to criminal law. National and international perspectives. In Criminology of Contemporary Ecological Threats (ed. M. Kotowska & W.Pływaczewski), pp. 94–105. Olsztyn, Poland: Katedra Kryminologii i Polityki Kryminalnej, Uniwersytet Warmińsko-Mazurski.
5 Białocerkiewicz, J. (2005). Legal status of animals. Animal rights or legal protection of animals, 319pp. Toruń, Poland: Dom Organizatora.
6 Mukerjee, M. (1997). Trends in animal research. Świat Nauki 4, 68–76.
7 Krenzer, F. (2004). Morgen wird man wieder glauber. [You will believe again tomorrow. A Catholic faith information book.], 41st edn, 380pp. Limburg, Germany: Lahn-Verlag.
8 Kożuchowski, J. (2011). Ethical responsibilities of man toward the world of animals. Robert Spaemann’s Vision. Studia Ecologiae et Bioethicae UKSW 9, 29–48.
9 Guzek, J.W. (2005). Outline of Human Pathophysiology, 699pp. Warsaw, Poland: PZWL.
10 Frey, R.G. (1983). Vivisection, morals and medicine. Journal of Medical Ethics 9, 95–104.
11 Singer, P. (1995). Animal Liberation, 368pp. London, UK: Pimlico.
12 Pisula, W. (2001). Introduction to the monograph. In
Animal Minds
(ed. D.R. Griffin), pp. 16–17. Chicago, IL, USA: University of Chicago Press.
13 Griffin, D.R. (2004). Animal Minds, 320pp. Chicago, IL, USA: University of Chicago Press.
14 Spaemann, R. (2001). Grenzen: Zur Ethischen Dimension des Handelns [Borders: On the Ethical Dimension of Actions], 427pp. Stuttgart, Germany: Klett-Cotta.
15 Arzt, V. & Birmelin, I. (2001). Haben Tiere ein Bewusstsein [Do Animals Have Consciousness?], 279pp. Warsaw, Poland: Bertelsmann Media.
16 Vetulani, J. (2014). Bright prospects for thinking. Interview conducted by Rafał Romanowski, Żyjmydłużej 2, 10–13.
17 Szyszko, S. (2005). Epitaph for a dog (a few comments on ‘vivisection’). Przegląd Medyczny Uniwersytetu
1, 95–98.
18 Kornas, S. (2005). Animal experimentation. In Encyclopedia of Bioethics. Christian Personalism. The voice of the Church (ed. A. Muszal), pp. 128–132. Radom, Poland: Polskie Wydawnictwo Encyklopedyczne.
19 Żukow-Karczewski, M. (2013). Medical experiments and research involving animals. Polska: Wolnemedia.net. Available at: http://wolnemedia.net/historia/eksperymenty-i-doswiadczenia-medyczne-nazwierzetach/ (Accessed 21.05.13).
20 Feinberg, J. (1978). Human duties and animal rights. In On the Fifth Day: Animal Rights and Human Ethics (ed. R. Knowles Morris, R. & M.W. Fox), pp. 11–38. Lancaster, UK: Gazelle Book Services Ltd.

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Lost in Translation: The Need for Better Tools

Susanna Penco, Elena Venco and Alfredo Lio

Although for most pharmaceutical compounds
the final aim is improving human health,
almost all the methods used to identify and
pursue therapeutic targets and to obtain
new potential drugs have traditionally
focused on animal models

Recent studies on attrition rate in pharmacological research show that the pharmaceutical industry finds it difficult to turn new experimental compounds into safe and effective drugs. Although, for most pharmaceutical compounds, the final aim is improving human health, almost all the methods used to identify and pursue therapeutic targets and to obtain new potential drugs have traditionally been centered on animal models. The ability of such methods to predict efficacy and safety in humans needs to be carefully reviewed, in the light of more-predictive and more reliable human-based experimental tools.

The overall cost for the development and the marketing of a new pharmaceutical product ranges between one billion and 1.8 billion US dollars.1 It has been estimated that only one in 10,000 new chemical entities (NCEs), also referred to as new molecular entities (NMEs), discovered in the laboratory succeeds in obtaining marketing approval.2, 3 Recent studies have shown that 95% of experimental drugs fail in the clinical phase.4, 5 The main reasons for these poor results can be ascribed to the lack of therapeutic efficacy and safety.6, 7 Such findings point to the significant inadequacy of the current preclinical tests — mainly in vitro cellular assays and animal based disease models — in screening pharmacological compounds. Many in vitro tests are still performed in a two-dimensional format,8 despite the limitations of this approach,8, 9 and are based on animal cells, which complicates the potential extrapolation of the information they provide to humans.6, 10, 11 In spite of this, such preclinical methods are still considered the ‘gold standard’ in pharmaceutical R&D.

The relevance of animal models
Many animals, including mice, rats, dogs, cats, and non-human primates (NHPs), are used in biomedical and toxicological research as human disease surrogates, so they are defined as ‘animal models’. However, there are a number of important limitations that underlie the lack of successful use of these animal models in furthering the understanding of human disease.

Firstly, there are significant differences among species with regard to their anatomy, metabolism and physiology, which correspond to genetic differences, including differences in regulatory genes. This means that even slight molecular differences can be amplified in the extrapolation process from one species to another. For instance, mice (together with rats, which are the most commonly used species in biomedical research) share with humans slightly more than 90% of their gene sequences. Nevertheless, at least 67 major discrepancies have been found in the immunological functions of mice and humans. This fact is hardly surprising, since these two species separated approximately 65- to 75-million years ago, and have since followed different evolutionary path ways.

About 1% of human genes do not have a homologue in the mouse.14 Biochemistry provides many examples concerning similarities and differences between species. Some of the most significant differences are in the cytochrome P450 enzymes (CYPs), which seem to have evolved from a single ancestral gene over a period of 1.36 billion years. To date, at least 14 families of CYPs genes have been identified in mammals.15 Each member of this gene family has many highly conserved regions in its secondary amino acid structure. However, remarkable differences between species also exist in the primary amino acid sequences. Even small differences in amino acid sequence can imply wide differences in substrate specificity.16 Such variations can explain the divergences in drug response between animal models and humans. The scientific literature provides many examples of therapies that proved successful in animal models, but subsequently failed in clinical trials.17-20

A second important issue surrounding the failure of many animal models is the way in which the disease is induced. Diseases induced ‘artificially’ in animals cannot begin to accurately reproduce the very complex aspects and conditions clinically observed in human patients. This is thought to be one of the most crucial reasons for drug attrition.21, 22

In addition, there are relevant species-specific differences in absorption, distribution, metabolism, excretion and toxicity (ADMET) between animals and humans.23 These processes together make up the important concept of ‘pharmacokinetics’.

Pharmacokinetics is one of the main reasons for candidate compound failure in humans.24 A wide range of species-specific metabolic patterns strongly suggest that data can be hardly (at best) extrapolated from one species to another, both quantitatively and qualitatively — i.e. differences in the amino acid sequence of isozymes may influence both the rate of drug metabolism and the metabolite pattern. 25 An outstanding example of species-specific differences between rats and humans is in coumarin metabolism and toxicity, which appears to be mediated through two major phase I metabolic pathways. The first pathway, involving cytochrome CYP2A enzymes and leading to the conversion of coumarin into the non-toxic metabolite 7-hydroxycoumarin, is very efficient in humans and extremely inefficient in rats. The second pathway involves the detoxification of the epoxide intermediate, coumarin 3,4-epoxide, which spontaneously rearranges to o-hydroxyphenylacetaldehyde and is then oxidised to o-hydroxy – phenylacetic acid. In rats, the rate of conversion to o-hydroxyphenylacetic acid is 50 times lower than in humans. These metabolic discrepancies explain the differences in coumarin-mediated hepatotoxicity between the two species.26

There are many significant examples of drug attrition resulting from the limitations of the animal models used in pharmaceutical R&D:
— More than 150 experimental therapeutics for the treatment of sepsis have been successfully tested in animals. None of them proved useful in humans.27
— A total of 800 new drugs showed promising results in animal models for stroke, but only 97 were approved for the clinical phases. Unfortunately, only two showed some efficacy, with aspirin being one of the two.28, 29
— More than 85 different HIV vaccines have been tested in approximately 200 clinical studies,30 but to date no therapeutic or protective effects on humans have been found. The use of resources has been so extensive that, even if an effective HIV vaccine were found as a result of animal experimentation, animal models could not be considered a suitable predictive experimental method, since the PPV (positive predictive value) would be around 0.01.31

The list of failures gets longer with anti-cancer drugs, and there is also an endless list of failures in relation to neurodegenerative diseases. Indeed, anticancer drugs and treatments for neurological diseases have the highest attrition rate in the development process.32 Awareness of the limits of the predictivity of animal models is rapidly growing.33-39 Even the use of transgenic animals seems to have proved inconclusive in translational medicine.6, 34, 40-42 With regard to neurodegenerative diseases, the results obtained by testing new therapies on animals have been very poor.17, 43, 47

The study of bioavailability is a clear example of the differences in drug response occurring among species, as shown by many studies.48-51 Systematic reviews of the predictive accuracy of animal models in the field of teratogenesis52, 53 and carcinogenesis,54 also showed poor predictive power. In a recent analysis of the registration files of all therapeutic monoclonal antibodies (tmAbs) available in the EU, van Meer et al.55 discovered that the incidence of formation of anti-tmAb antibodies in NHPs and patients was comparable in only 59% of cases. In addition, the type of anti-tmAb antibody response was different in NHPs and humans in the same proportion of cases. The authors concluded that monoclonal antibody immunogenicity in NHPs and humans is significantly different.

In a recent review of the use of the dog model and other animal models in drug toxicology, the authors concluded that its predictive value in current toxicology was very poor.56, 57 The issues associated with extrapolating data from animals to humans are probably due to both inadequate testing procedures and to the failure of models to accurately reproduce human diseases, but evidence is growing that the core of the problem could only be resolved by giving up the use of animals as models.33 Therefore, in the light of controversial predictive value, it is not surprising that some scientists consider preclinical animal studies, “generally scarce, unreliable or nonpredictive”. 58-60

Considering the present stalemate of translational medical science, the development of new, reliable experimental approaches to assure efficiency, convenience and safety in clinical therapies is desperately needed. Long-term Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) studies, comprising a set of in vitro tests based on human biological materials, proved more predictive in testing compounds than did traditional animal-based acute toxicity studies.61
Recently, many important improvements have been made in studying acute toxicity, repeated toxicity62 and reproductive toxicology, as assessed by the ESNATS report.63-64 One particularly promising field is that of organs-on-chips, which are micro-engineered physiological systems aimed at reproducing the physiological properties of human tissues and organs and their interactions. Thanks to these biochips, it has been possible to create a model for acute pulmonary oedema that has permitted the evaluation of new clinical and therapeutic interventions.65 In addition to the lung-on-a-chip, other tools have been successfully developed to mimic the human gut66 and kidney.59 The final aim is clearly to develop a ‘human-on-a-chip’, to fully mimic the functions of and interactions between organs, thus getting closer to the human in vivo situation. Indeed, some already trust this approach as a valid alternative to traditional animal tests.67-70 In addition, the use of human pluripotent stem cells seems to be becoming more widely appreciated in pre-clinical toxicology.71-72

Since the available data show that their predictivity can no longer be assumed, there is an urgent need for reviews and meta-analyses of the animal models currently used in medical research. Moreover, science should focus on the development of more-advanced methods, as a result of the limitations of the current pre-clinical tools, the growing bioethical objections surrounding their use, and the ongoing development
of new in vitro and in silico techniques. These alternative methods should be used ideally in the experimental context of an Integrated Testing Strategy.

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