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Q&A: Using human-admixed embryos for stem cell research

This Q&A page provides the O&G perspective on using human-admixed embryos for stem cell research. It was published by the RCOG in May 2008 to accompany the passage of the Human Fertilisation and Embryology Bill through Parliament.

What are ‘human-admixed’ embryos?

Human-admixed embryos are also known as ‘cytoplasmic hybrid’ or ‘interspecies’ embryos. An egg cell from a cow (or rabbit) has its nucleus (DNA) removed so that all that remains is an egg sac and cell fluid (cytoplasm) that contains less than 1% of animal genetic material. Nucleus from human skin cells are then introduced into the egg and an electric current is passed through so that the nucleus and cell fluid fuses and the cell is jolted into beginning the process of division. These embryonic cells are 99% human.

What are human-admixed embryos used for?

As the embryo grows, it produces stem cells. Stem cells are the basic building blocks of life as they can transform into any other type of cells, e.g. blood cells, heart cells, liver cells.

Scientists believe they can study the development of these cells and develop cures in the future for debilitating diseases such as Parkinson’s, Alzheimer’s, diabetes, stroke and rheumatoid arthritis.

Why do scientists want to use cow eggs instead of human eggs?

Human eggs are in short supply. They are used in in vitro fertilisation (IVF) treatment to help childless couples become parents. Cow eggs, on the other hand, are in abundant supply.

Are there any safeguards regulating the use of human-admixed embryos in stem cell research?

Such research will come under the scrutiny of the Human Fertilisation and Embryology Authority (HFEA). Scientists will have to apply for licences and to have these approved before they are allowed to develop human-admixed embryos and undertake stem cell research.

There will be special conditions governing such research. Measures are in place to prevent these human-admixed from being implanted into the womb of a human or an animal. All embryos will be destroyed after 14 days.

So if the purpose of using human-admixed embryos is to advance our understanding of diseases and to cure them, what is all the fuss?

There are individuals and groups who believe that the combination of animal and human cells will create chimeras, or a new species of life that is part human, part animal. These groups are also against the idea of creating life and then destroying it.

Research is conducted in a laboratory and at these very early stages, the cells are still organising themselves. By researching the growth of cells up to the first week, scientists want to gain better insight into the early stages of cellular development, the purpose being to examine the process of cell renewal and tissue building. With this knowledge, it is hoped that scientists will be able to find cures for diseases. This process of observation and deduction has lead to the development of medicines and vaccines for a range of illnesses throughout the centuries.

Currently, the UK is one of the leading centres for stem cell research in the world. Other countries involved in such tightly-controlled research include Canada, China, Finland and Israel. In order for the UK to remain at the forefront of international scientific research, it must engage in this work.

What is the RCOG’s position on the use of human admixed embryos for scientific research?

The RCOG believes that stem cell research has a very promising future in the development of cures for diseases. However, at this very moment, because of the shortage of human eggs, the best and safest alternative is to resort to carefully chosen cow eggs which have had their DNA removed.

Can’t we just get more women to donate their eggs for scientific research?

The harvesting of human eggs is a potentially painful and difficult experience for some women. In extreme cases, it can be fatal. Some may have an adverse reaction to the fertility drugs used to collect their eggs and go on to have a condition known as ovarian hyperstimulation syndrome (OHSS). The symptoms range from mild where a woman feels bloated and nauseous; to the serious, where she has difficulty in breathing and has blood clots that could lead to death.

Can’t we use the ‘left-over’ eggs from IVF treatment for stem cell research?

Not all eggs collected are of a good quality and only the best eggs are selected for IVF. The success of IVF treatment differs from women to women. A mix of chance and biology sometimes results in a successful pregnancy after just one cycle of IVF treatment, while for other women, the process takes longer. For these women, they will need their eggs for later use. For women who have been successful, they sometimes donate their eggs to other women undergoing IVF. Some women may want to store their eggs for future use, should they decide to have another child at the later stage in life. The supply of good quality human eggs is therefore very small.

There has been much talk recently about new scientific developments whereby stem cells have been created from human skin cells and the separate suggestion that stem cells should be extracted from umbilical cord blood instead of embryos. Advocates of these two ideas suggest that stem cells should be derived from these sources and not through embryonic stem cell research. What is the RCOG’s view?

New scientific advancements mean that there is the potential to collect stem cells from new sources. The ability to derive stem cells from human skin cells is still very new and the opportunities to engage in such work are, at this moment, limited.

In terms of collecting stem cells from umbilical cord blood, this is not the same as studying the early cellular development of stem cells in embryos specially cultured for research. The advantages of this type of research means that scientists are able to study how diseases grow at molecular stage whereas stem cells from umbilical cord blood are already formed. Currently, the availability of umbilical cord banking is limited in the UK. There isn’t the infrastructure and resources to ensure that a steady supply of stem cells can be obtained from present cord blood stores.

The RCOG supports further research into deriving stem cells from existing human cells and an expansion of the public banking of umbilical cord blood but believes strongly that licences for embryonic stem cell research should be granted until new methods make this process obsolete.

Finally, what are the advantages of using human-admixed embryos and stem cell research in respect of their contribution to mankind?

The RCOG believes that public health benefits will be gained through carefully- controlled stem cell research using human-admixed embryos. Should such research be proven to be harmful at any stage, the RCOG will work with the Government and HFEA to ensure that research ceases immediately.


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