Half-Truths?: The science, politics and morality of hybrid embryos

The creation of human admixed or 'hybrid' embryos - which contain both human and animal material - is perhaps the most controversial aspect of the Human Fertilisation and Embryology (HFE) Bill, and is an issue on which UK Prime Minister Gordon Brown bowed to pressure for a free vote by MPs, following reported dissent in the Cabinet and a concerted mobilisation by the Catholic Church.

Human admixed embryos have long been used to test the viability of human sperm, the Human Fertilisation and Embryology Authority (HFEA) has granted licenses for the use of such embryos in disease research, and there has been preliminary news of embryos created from human skin cells and cow eggs at Newcastle University. But as campaigners mount a legal challenge to this work, supporters and detractors of the research accuse one another of wilfully misleading the public.

While in the Commons MPs voted on whether or not to allow human admixed embryos for research, a diverse audience of policy makers, journalists, patients, academics, clinicians, students and lay publics gathered to see the science, politics and morality of the issue debated at a public event organised by Progress Educational Trust at the Houses of Parliament on Monday 19 May.

The event was expertly chaired by Fiona Fox, Director of the Science Media Centre, who was pleased to welcome three expert speakers: John Burn, a scientist involved in stem cell research and Professor of Genetics at Newcastle University, Josephine Quintavalle, co-founder of the pressure group 'Comment On Reproductive Ethics' and Brenda Almond, Emeritus Professor of Moral and Social Philosophy at the University of Hull and member of the Human Genetics Commission.

John Burn opened the discussion with a basic overview of human admixed embryos for the benefit of non-expert audience members. He emphasised that such embryos - created by inserting the nuclei of human cells into animal eggs - are, in terms of their genetic makeup, 99.9 per cent human. He went on to highlight some of the most widespread uses of stem cells, such as the creation of 'disease-in-a-dish' models of human disease, the study of 'epigenetics' - environmental influences that change the way genes are expressed - and the development of revolutionary new treatments for diseases including Parkinson's, Alzheimer's, Cystic Fibrosis and Heart Disease.

Burn felt that the HFEA - the government regulatory body for embryo research - should be trusted to ensure that embryo research is both safe and ethical. While admitting that research on adult stem cells, where skin cells are genetically manipulated to revert back into an embryonic state, has begun to show some promise, Burn said that embryonic stem cells provide the gold standard necessary to advance all other avenues of stem cell research.

Josephine Quintavalle, who has many years experience of campaigning for the right to life of the embryo, felt that a number of 'myths' had been sold to the public surrounding the debate over human admixed embryos. She highlighted that although the so-called 'hamster test' - where human sperm are mixed with hamster eggs to test their viability - has been used by stem cell advocates to argue that human admixed embryos have been in use for decades, this application was never intended as a precursor for their use in the context of stem cell research.

Furthermore, Quintavalle felt that the principle that 'all roads must be kept open', seemingly upheld by the Bill, was not one on which good science should be based. She felt strongly that the public had been falsely lead to believe that the UK are world leaders in stem cell research, whereas in reality other countries such as South Korea, who she says have just opened up the largest cord blood stem cell bank in the world, are far more likely to bring scientific breakthroughs to this field. Given the huge sacrifice of human embryos to date in stem cell research, said Quintavalle, it was surprising that more scientific breakthroughs had not been forthcoming.

Brenda Almond, last to speak, felt that anxieties over hybrid embryo research had been fuelled by confusion over the definition of an embryo. Highlighting that for a long time the accepted definition of an embryo had been a 'fertilised egg' - the point at which a sperm and an egg fuse together - Almond said that it was understandable for there to be strong objections to what some see as their misuse. She explained that the development of cloning technology, which creates embryos without fertilisation, was responsible for triggering a shift in how embryos are defined. Given that our science has been updated in this way, Almond felt that there was an urgent need for our language to follow suit.

Almond's second point related to the need to distinguish more clearly between embryos created for scientific research and those created in fertility treatment. Although the Bill recognises the importance of maintaining this line by banning research on embryos older than 14 days, Almond suggested that a specialist group should be appointed in order to govern the very complex, sensitive and controversial area of research involving early-stage genetic material.

Following the talks, the 120 strong audience made for a lively debate. Several audience members questioned the need to pursue embryonic stem cell research when other more ethically acceptable avenues have yet to be exhausted. In response, Burn pointed out that many of the breakthroughs in adult stem cell research have happened in the US, where embryonic stem cell research is largely outlawed. Quintavalle highlighted that scientists now know more about embryos than ever, stating that in March 2008, 1987 clinical trials had taken place using adult stem cells and 106 using cord blood, while to her knowledge none had used embryonic stem cells. From the floor, another commentator highlighted that it takes time to build up the pre-clinical data needed to inform a clinical trial and, given that human embryonic stem cell research has only been permitted in the UK for about five years, he would be 'horrified' if anyone had launched a clinical trial within that time.

Another audience member commented that many stem cell researchers work on both adult and embryonic stem cells and that if one succeeds the other, the HFEA will adapt their decisions over which deserve licences. In defence, Quintavalle pointed out that the HFEA had already granted two licences for human admixed embryo research ahead of any legislation or debate, while Marcus Pembrey, Emeritus Professor of Clinical Genetics at the Institute of Child Health, said that until adult and embryonic stem cell research are equally advanced, both are needed for truly ethical clinical trials to take place.

Another popular theme was the moral status of the embryo. One audience member said that it is important not to discount our moral sentiments, as these help to guide reason. Almond emphasised that an embryo is evidently not 'just a ball of cells' as people would understandably be very upset to find out that they were being used in any frivolous way. But, conversely, she felt that using an embryo to achieve something very important could evoke very positive feelings, especially if that embryo was destined to be destroyed in the first place.

David King, Director of Human Genetics Alert, said that, given the relative size of a hollowed out animal egg compared to a human nuclei, it was nonsensical to judge the degree of humanity of an embryo by its genetic makeup alone. He felt that stem cell research based on admixed human embryos risked misleading scientists in the event that models for human disease were later found to be defective. Burn responded by emphasising that the only reason for pursuing this line of research would be to help solve the current problem of the lack of human eggs with which to generate embryos. He said that admixed human embryos would only be used to establish the basic principles of stem cell research, in order that these can later be tested using the very limited supply of human eggs that stem cell researchers have available to them.

During the course of this public debate, MPs voted down a bid to ban human admixed embryo research by 336 to 176 votes and another to ban true hybrids by 286 to 223 votes. Throughout the event, the periodic ringing of division bell calling MPs to vote on these issues was a reminder of the timeliness of this debate. Progress Educational Trust's next debate, 'Cousin Marriage: A cause for concern?' will take place in London on 28 May 2008 - see 'Recommends' for how to book a place at what promises to be another lively event.