The British Heart Foundation (BHF) funds animal research into heart disease. Yet the results from animal experiments cannot be reliably applied to humans, and this means they are unlikely to result in medical progress. Below are just some of the reasons for this:
1. There are fundamental differences between humans and animals. Dogs, for example, cannot be made to develop heart disease by being fed an artificially fatty diet. Rodents have a resting heart rate five times higher than humans, with different electrical impulses and muscle composition.[i] Zebrafish, who are often used in heart disease research, have a two-chambered heart, whereas human hearts are four-chambered.
2. For research into heart attacks and heart failure, healthy animals are often grievously injured, but the disease produced is markedly different from those found in human patients. For example, researchers have resorted to gradually destroying the hearts of dogs by injecting polystyrene beads into their coronary arteries.[ii] This clearly bears little relation to the development of heart disease in humans, which may occur over several years and result from a complex web of factors.
3. Animals are also genetically engineered in an effort to mimic human heart disease, but this does not remove the fundamental differences between species that prevent the results of animal experiments from being reliably translated to humans. For instance, mice have been genetically engineered to overproduce a chemical suspected to worsen heart failure (TNF-alpha), and suffer enlarged, baggy hearts and premature death. Some of them showed improvements in heart function when treated with a drug that blocked TNF-alpha receptors, but a human drug trial using the same substance failed.[iii]
4. Whether the animals have been subjected to surgery or genetic modification, these misleading ‘models’ have led to a catalogue of research failures. For example, stem cell trials on animals generated a great deal of ‘positive’ data, but human trials that involved injecting stem cells into patients’ hearts during bypass surgery had to be stopped when they experienced life-threatening irregular heart rhythms. Extensive animal experiments had given no indication that this would happen. [iv]
5. Animals have certainly been used during the development of therapies for heart disease, but this does not mean that their use was either necessary or helpful. In fact, it is possible that potentially useful treatments have been lost as a result of misleading animal data. Statins (cholesterol-lowering drugs) are a case in point. Many human clinical trials of mevastatin, one of the first statins to be researched, were suspended in mid-1980 when the drug was found to produce toxic effects in some dogs at higher doses in a long-term toxicity study. It was only the beneficial effects observed in humans that caused researchers to persevere.
6. It is true that some animal experiments into heart disease cannot be replicated without the use of animals. But given the failure of such experiments to deliver benefits for human medicine, it is time they were abandoned anyway. In contrast, there are numerous non-animal methods of conducting research into heart disease that are directly relevant to humans. These include the use of human-derived raw materials (such as tissues, cells and DNA), computer modelling, microfluidics and high resolution scanning. There is also a range of important traditional methods such as autopsies and clinical studies. A good example of a human-based discovery is the angioplasty procedure. It was first discovered when a doctor used a piece of tubing made from Teflon to treat a blocked artery in a patient’s leg. Now, the procedure is used extensively to treat narrowed arteries and blockages in the heart – as well as in other areas of the body – without the need for invasive surgery. [v]
Victims of Charity: a detailed but accessible report into the failure of animal research into major diseases and the role played by medical research charities.
Briefing on non-animal research methods: inspiring case studies showing what can be achieved without animal suffering.
Animal Aid’s response to the BHF: a detailed response to a BHF leaflet entitled Animals and Heart Research.
[i] Klocke R, Tian W, Kuhlmann MT et al (2007). Surgical animal models of heart failure related to coronary heart disease. Cardiovascular Research. 74:29–38
[iii] Patten RD, Hall-Porter MR (2009). Small Animal Models of Heart Failure: Development of Novel Therapies, Past and Present. Circ Heart Fail. 2:138-144
[iv] Dimmeler S, Zeiher AM, Schneider MD (2005). Unchain my heart: the scientific foundations of cardiac repair. J. Clin. Invest. 115:572-583