Cloning 'threat' to egg supplies

To create a clone, a cell's nucleus is fused with an empty egg

By the BBC's David Concar

There is renewed debate over plans by the UK Government to allow limited research into human cloning.

Some fertility experts say it could trigger fierce competition for human egg donors - possibly threatening supplies of eggs to clinics where they are needed to treat infertile couples.

Dr Tony Rutherford of Leeds General Infirmary, UK, told the BBC that there is already a shortage of volunteers willing to donate eggs.

He is concerned that supplies will be reduced still further, if researchers are given the go-ahead to use human eggs for cloning work.

Dr Rutherford said: "They are going to need healthy volunteers just as we need healthy volunteers.

"We've seen an increase in demand for egg donors of 20-25%, year-on-year, over the last three to four years. At the moment, we've got a hundred couples on the waiting list."

'Stringent controls'

MPs are due to vote on whether to allow limited research into human cloning during the current session of Parliament.

The aim of this research is to reprogram cells so it's hoped, perhaps in the longer term, that the whole question of using eggs and embryos would simply not come up

Dr Sandy Thomas

Many scientists believe that such research is necessary to develop replacement tissues for transplant or to treat crippling diseases using stem cells extracted from embryo clones.

Stem cells have the unique capacity to replicate themselves and to generate more specialised cell types as they multiply.

But in order to carry out the work, scientists would need to use human eggs as well as early human embryos.

Dr Sandy Thomas, director of the Nuffield Council on Bioethics, told the BBC that although human eggs are in short supply, researchers wanting to use these eggs for cloning work would have to apply for permission.

"I don't think one should be too hasty to make a connection between eggs for IVF treatment and eggs that might be used in this kind of research," she said.

"The first step that one would foresee is that applications for this kind of research would have to be made on a case-by-case basis to the authority, which is the Human Fertilisation Embryology Authority, and each application would be looked at in terms of what it proposed to do.

"The aim of this research is to reprogram cells so it's hoped, perhaps in the longer term, that the whole question of using eggs and embryos would simply not come up. One would be able to reprogram cells directly to be able to make stem cells - that's the real objective," Dr Thomas added.

Cultured eggs

Scientists are trying to address the problem of a shortage of egg donors by developing ways of growing human eggs from ovarian tissue in the test tube.

Researchers in Leeds are carrying out tests on cow ovaries to see whether they can stimulate the hundreds of immature eggs found in an ovary to develop into mature ones suitable for fertilisation.

One of the scientists, Dr Helen Picton said: "If we can successfully develop the technology which will enable us to culture the very small eggs up to full size in the culture dish then we have the potential to harvest hundreds of eggs from a small piece of tissue for donation or for research."