Embryo Research

A number of recent consultations have considered the issue of creating embryos for research that contain both human and animal genes (sometimes called interspecies embryos).

The Human Fertilisation and Embryology Authority decided on 5 September 2007 to consider licence applications for research on human-animal cytoplasmic hybrid embryos. The government brought its Human Fertilisation and Embryology Bill to parliament (November 2007), and agreed that all interspecies embryos, including true hybrids, should be permitted under this Bill for research purposes, leaving the regulator to decide each individual research application on its merits.

The purpose of some embryo research is to produce stem cells: unspecialised cells which can develop into any of the body's 200 or so different specialised cell types.

In this policy briefing on a fast-evolving area of biology, we discuss:

• Why do scientists want to do this research?
• What sorts of embryos might be created?
• What do we say about the regulation of this research?
• Can scientists influence legislation?
• Recent consultations on interspecies embryos for research
• Where to get more information

Why do scientists want to do this research?
Stem cells from interspecies embryos could be used to understand a number of intractable human diseases, including Parkinson's, Alzheimer's and motor neurone disease, which are difficult to study in other biological systems. They might also be used to screen for potential treatments for such diseases.
Human eggs for could in principle be used for this research, but they are in very short supply and often of poor quality.

Good quality animal eggs are plentiful, for example from abattoirs (where they would otherwise be discarded). Using animal eggs avoids potentially harmful and invasive procedures on human donors, and might also reduce the need for research on live animals.

At the moment, alternative methods for studying neurological diseases do not show the full range of human symptoms and may not offer much hope of developing new treatments for these debilitating diseases. Proposed UK research using cell lines from human-animal interspecies embryos offers new tools for both basic science and drug screening.

While not offering treatments in the short term (nor any guarantee of future therapies or cures), the new method should accelerate the pace of research since the cell lines would be deposited in the UK stem cell bank (as required by the licensing procedure) and would therefore be freely available to scientists in universities and companies around the world.

What sort of embryos might be created?

Cytoplasmic hybrid embryos are formed by removing the nucleus from the egg of one species (eg a cow), and fusing the emptied egg with an intact cell from another species (eg a human). Cells in the resulting embryo will contain a human nucleus, and both human and cow mitochondria. As the cells divide, the cow mitochondria decrease in number since the nuclear genes required for forming cow mitochondria are lost when the cow nucleus is removed. Once the resulting embryo is about five or six days old (and is still the size of a grain of sand), cells can be removed to be grown as embryonic stem cells and the embryo itself is destroyed. The stem cells can then be grown in the lab and used for a range of further studies, for example into human diseases.

Chimeras are made by combining intact embryonic or other cells from two different species. Making chimeras by injecting embryonic stem cells into embryos is presently the only way of establishing conclusively whether they are normal, and are therefore safe to transplant into patients. Since it would be ethically unacceptable and illegal to produce such chimaeras in humans, testing the normality of human embryonic stem cells may depend on injecting them into blastocysts of other species, unless other reliable assays can be devised.

True hybrid embryos are created by fertilising the egg of one species with sperm from another. Researchers in the UK do not currently see any reason for creating human-animal hybrid embryos.

What do we say about the regulation of this research?
We believe that research on interspecies embryos in the lab should be allowed, provided that it is regulated and licensed in the same way as research on human embryos, and is subject to the same stringent scrutiny and controls.

The broad limits and purposes of human and interspecies human-animal embryo research should be defined by law with specific guidance provided by the regulator (taking advice from its science and ethics specialists, lay members and committees).

It is important that research is regulated and carried out in a manner that earns public confidence and support. We recognise that there are legitimate ethical concerns about research on embryos which contain both human and animal material, and believe that policy makers should seek and consider diverse views when developing legislation in this area.

Public support for this type of research requires scientists to act ethically, to be willing to understand and address people's concerns and aspirations, and to explain the reasons, benefits and alternatives to this research.

As this fast moving field develops, the regulator should continue to seek and consider informed public opinion on the acceptability and benefits of new areas of research, along with professional advice on the science and ethics, when updating its guidelines.

Individual research applications should continue to be considered case by case by the regulator.

Can scientists influence legislation?

For an example of the impact of proactive engagement with the public, the media and parliament, you can do no better than reading Hype, hope and hybrids: science, policy and media perspectives of the Human Fertilisation and Embryology Bill, edited by Geoff Watts. This is a fascinating account of how scientists – by taking the initiative to explain why they believed that their research was important and necessary – persuaded the government to permit research using human-animal hybrid embryos.

Recent consultations on interspecies embryos for research

We responded to the following consultations:

18 Jan 2007
Hybrid and chimera embryos
Response to the House of Commons Science and Technology Select Committee

15 June 2007
Draft human tissue and embryos bill
Response to the Joint Select Committee

10 July 2007
Hybrids and chimeras
Response to the Human Fertilisation and Embryology Authority

1 Aug 2007
Draft human tissue and embryos bill
IoB comment on the Joint Select Committee report

Where to get more information
The Human Fertilisation and Embryology Authority consultation papers on Hybrids and Chimeras gives useful background information on this research and its ethical and social implications. More detailed discussions are in the report of the House of Commons science and technology select committee. The Government response to the joint select committee, on 8 Oct 2007, accepted some of our key recommendations. The Human Fertilisation and Embryology Bill was introduced to parliament in November 2007.