PRESS RELEASE - 2 January 2002 - Immediate release
Cautious Welcome for "Knockout" Pigs but Ethical Doubts Remain
Dr Donald Bruce, Society Religion & Technology Project, Church of Scotland
Tel. 0131-240 2250, Fax 0131-240 2239,
Email: srtp@srtp.org.uk http://www.srtp.org.uk
or Church of Scotland Press Office 0131- 240 2243
The SRT Project gives a cautious welcome to today's announcement of the birth of 5 cloned "knockout" piglets PPL Therapeutics' US subsidiary company. This development was already prefigured in a report GM Animals, Humans and the Future of Genetics by the Society Religion & Technology Project at the May 2001 General Assembly of the Church of Scotland. The Assembly gave cautious approval of this area of research into using transgenic animal organs in humans, but also made important ethical caveats.
In general, to disable the normal function of an animal should not be done except under very special circumstances. This is because, as many Christians and others believe, animals have intrinsic value. This means that, while we may use animals for some purposes, they are not simply tools for our convenience. The more serious the intervention in an animal, the more serious must be the human need which it seeks to meet. The disabling of the gene which would otherwise cause the rejection of a pig organ by the human body might, potentially, be ethically acceptable in the context of xenotransplantation, but only provided a number of conditions were fulfilled. The prospect of using pig organs to save many human lives, or to improve substantially the quality of life of dialysis patients or diabetics, is attractive from the viewpoint of human medicine. But it raises serious ethical issues over the use of animals and a major question of safety.
1. Xenotransplantation raises ethical issues about animals.
Using live pig organs in humans would be a serious intervention in one of God's creatures with whom we share the planet. Pigs are highly intelligent animals for whom many humans have a special fondness. The fact that we already eat pigs already is not a sufficient moral argument. This would be an entirely new way of relating to animals. Eating a pig is at least doing no more than happens in nature. Switching organs across species represents a different way of using animals from anything humans have done before. For more about the ethical issues, see SRT's report on the Ethics of Xenotransplantation and our book Engineering Genesis.
2. Ethical justification only of it really worked well
Xenotransplantation would be justified only if it gave a long remission of terminal illness and a substantially improved quality of life which could not be achieved in other ways. To do this it needs to overcome a number of difficult technical and safety hurdles. PPL's announcement of knocking out of one rejection gene makes the case for stronger, but there are still many other problems to be overcome. For example, several other genetic changes are also required. Only if all the rejection mechanisms can be overcome sufficiently would the medical case be strong enough. "It is justified to conduct research while this remains a realistic prospect, but is not a foregone conclusion" says the Church of Scotland 2001 report GM Animals, Humans and the Future of Genetics.
3. Virus risk remains a serious concern.
In 1996 laboratory research into possible transmission of pig retroviruses to humans led the Department of Health to call for a moratorium on clinical trials while virus transmission to the human population was investigated further. The Human Xenotransplantation Interim Regulatory Authority has produced stringent guidelines for any clinical trials, to monitor patients, their families and all close contacts. Substantial data are needed to be sure that the risk of transferring pig viruses to the human population was extremely remote. Such an assurance is unlikely to be easily achieved. Xenotransplantation must take a "no, unless" approach on this point.
4. Is there a better alternative to Xenotransplantation?
Given these risks, some ask whether we actually need this xenotransplantation, when recent advances in human stem cells offer the prospect of replacement cells and possibly even replacement organs. This seems a premature claim. At the EC's major conference Stem Cells: Therapies for the Future? 18-19 December 2001, researchers and clinicians stressed that therapies based on human stem cells are mostly a long way off reality, and no one sees creating replacement organs as a serious prospect for the foreseeable future. Today, no one knows how effective either cell replacement or xenotransplantation would prove to be. Indeed there may be a synergy between the different routes, where gene deletion technology may help understand immune rejection in stem cell based therapies. See also SRT's paper Stem Cells and Cloning - Medical Potential and Ethical Dilemmas.
5. Other Gene Deletions
Gene deletion has been done in mice for many years, to test the function of genes identified in the human genome project and to study human diseases. This has used stem cell methods that remain unique to mice. PPL's work shows that gene deletion could, in theory, be extended to farm animals and any other animal that could be cloned. Knockout mice are ethically controversial, and the Church of Scotland has raised questions whether this has become too automatic a procedure because mice are still animals, not just items in a laboratory catalogue. The procedure would present greater ethical problems if extended to large animals without a very good reason.
A possibly ethically acceptable application is the proposal to replace a cow gene by a human one to make cow's milk more suitable for premature infants. If they are unable to be fed with their own mother's milk, premature babies may suffer some malnourishment because they lack certain important human proteins which the cow equivalent does not provide. The knockout method might therefore be used to delete the cow gene that "codes" for the particular milk protein, followed by adding the gene for the equivalent human milk protein instead. This is one step beyond existing methods which add a human gene without deleting the animal one, to which the
Church of Scotland has expressed ethical approval. One would need to be sure that the gene replacement did not compromise the animal in any way, but, with this proviso, the human benefit would seem to make this relatively acceptable. We would therefore urge a "no, unless" approach to gene deletion in farm animals, with a case-by-case examination of each potential application.
Further Information
SRT's report GM Animals, Humans and the Future of Genetics
SRT's pages on Ethics and Xenotransplantation
Press Release on Dolly's the Cloned Sheep's Arthritis
Our book Engineering Genesis on the ethics of animal and plant genetic modification
SRT's suite of pages on Human and Animal Cloning and Stem Cell issues
Dr Bruce is Director of the Society Religion and Technology Project of the Church of Scotland, assessing ethical issues in technology for Scotland's national church. He chaired an expert working group on the ethics of genetic engineering in animals and plants, which produced the acclaimed book "Engineering Genesis", which examined the ethics of both xenotransplantation and animal cloning. He is an external member of the ethical committee of PPL Therapeutics.
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