NOVEMBER was an astonishing month for embryonic stem cell research. First, Shoukhrat Mitalipov at the Oregon National Primate Research Center reported producing 鈥� the first from an adult primate. The decade-long dream of using cloned human stem cells to cure intractable diseases seemed on the verge of being fulfilled.
Just a week later, two research teams stunned the world by announcing they had generated genetically matched human pluripotent stem cells 鈥� which seem to be as versatile as embryonic stem cells 鈥� without cloning. Using viruses to introduce new genes into human skin cells, and , 鈥渞eprogrammed鈥� them to revert to an quasi-embryonic state.
鈥淐loning is not the only route to versatile stem cells that are a genetic match to adult donors鈥�
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So just as human therapeutic cloning seems achievable, a rival technique is challenging the idea that cloning is the only way to produce pluripotent stem cells that are genetically identical to their adult donors. , leader of the team that created , has said that he will abandon his efforts to clone human embryos and instead use reprogramming, which he sees as faster and more efficient.
Where does this leave the ethical debate around cloning? Is it right to use cloned embryos as a source of stem cells? Most discussion of this question has focused on the moral status of the human embryo. Little or no attention has been given to the risks that women face when donating the eggs needed for such research.
The process of egg donation inevitably involves some discomfort and pain: the woman is treated with hormones to stimulate her ovaries, and minor surgery is required to extract the resulting eggs. In the short term, she also risks : most donors suffer nausea, vomiting or abdominal pain, but severe cases can lead to .
The long-term health effects of these hormones are unknown. Some studies have found an increased risk of cancers of the reproductive system while others have not, and those who have received the highest doses are only now reaching the age at which cancer becomes common. So it is difficult for women to give fully informed consent.
A woman undergoing a similar procedure in order to become pregnant through IVF or to help another to do so knows there is a 10 to 40 per cent chance that her eggs will result in a baby. A donor for research, on the other hand, has no similar degree of certainty that her eggs will make any contribution to medical knowledge. Perhaps this is why recent attempts to recruit unpaid donors, such as in Massachusetts, have resulted in few if any volunteers.
Pressure has been building for the guidelines governing donation for stem cell research to be amended so as to allow women who donate eggs for research to be paid, just as women donating eggs for fertility treatment are in the US and some other countries. It is, however, scarcely ethical to offer young women large sums of money to undergo risky treatments of no direct benefit to themselves. We do not accept this with organs, so why with eggs?
One attempt to get round problem is 鈥渆gg-sharing鈥� schemes such as the one under way at Newcastle Fertility Centre in the UK. Women undergoing fertility treatment donate any extra eggs for research, in return for cut-price IVF. Proponents argue that as these women are receiving the drugs anyway, they incur no additional risks. But this approach is also morally dubious, as it presents doctors caring for the women concerned with an inevitable conflict of interest.
Cloning is a very inefficient use of eggs. Mitalipov needed 304 eggs from 14 monkeys to create just two stem-cell lines, and over the past decade his project alone has used a mind-boggling 15,000 eggs. The dilemma facing doctors who wish to harvest extra eggs from women undergoing IVF is that they will be tempted to maximise the number extracted from each donor by using high doses of hormones.
In any case, it may not be long before such treatments for the purposes of IVF will be considered outmoded and unsafe. Recent studies suggest that the risks of ovarian stimulation can be greatly reduced and even eliminated by using much lower levels of hormones, or none at all. These are also cheaper and less uncomfortable for the woman.
The potential scientific benefits of egg donation must be weighed up against the very real risks. Now that direct reprogramming offers a route to the same end that is equally if not more promising, there is no moral justification for asking women to give their eggs to cloning research. Some may argue that the cloning process 鈥� about which we understand very little 鈥� somehow generates cells of superior quality to reprogrammed ones. But this claim is as yet unproven, and unless and until it is, women should not be subjected to risky procedures that may very well not lead to better medical treatments.
