Thinking outside the egg
Scientists propose interspecies cloning
By Paul Elias
AP Biotechnology Writer
SAN FRANCISCO — It was nearly a decade ago that Jose Cibelli plugged his own DNA into a cow’s egg in a novel cloning attempt that was condemned as unethical by President Clinton and landed the Michigan State University researcher in a mess of controversy.
Even though Cibelli and his colleagues patented the so-called interspecies cloning technique, they soon abandoned the research as a failure and the uproar subsided.
Now the tempest is brewing all over again.
At least three respected teams of British scientists have reignited the moral debate over inserting human genes into animal eggs by proposing similar experiments to Cibelli’s.
Their goal is to eliminate the need for women to donate eggs for the cloning of human embryos, a research goal they say will enable them to better understand the genetic causes of many diseases, and design personalized medicines.
Currently, the few scientists actively pursuing human cloning are hobbled by a nearly nonexistent human egg supply. And each researcher will need thousands of them.
“Getting eggs from women is the bottleneck to cloning,” Cibelli said. “An alternative would be welcomed.”
All three U.K. teams aim to get around that bottleneck by taking DNA from patients sick with a disease like Alz-heimer’s and fuse it with cow eggs that have had all their genetic material removed. The hope is that the human DNA will trick the eggs into thinking they’re pregnant, beginning development.
After about five days of growth, the cloned embryos would be destroyed and the stem cells extracted. The stem cells would be grown in their labs and the researchers could look for the onset of diseases, study their development and test experimental drugs on the cells.
“You can model Alzheimer’s disease or Parkinson’s disease in a dish,” said Stephen Minger, director of the Stem Cell Laboratory at King’s College in London.
Minger’s request for a government license to use cow eggs instead of women’s eggs to generate human embryonic stem cells stirred significant controversy in the United Kingdom last year.
His application with the Human Fertilization and Embryology Authority — along with another from Lyle Armstrong of the North East England Stem Cell Institute — is expected to be ruled on later this year.
U.K. researchers are required to obtain government licenses to work with human embryonic stem cells. No such restrictions exist in the United States, though President Bush banned federal funding for most such research in this country.
Ian Wilmut, the U.K. researcher who cloned Dolly the sheep in 1997, said that if British government approves licenses for Minger and Armstrong, he’ll apply for a third.
“What has been overlooked in the cloning debate is the huge benefit it could have in drug discovery,” said Wilmut.
He and Minger were among the noted cloning experts who attended a research meeting earlier this month in San Francisco.
They and other scientists who have proposed doing such work argue it is an essential step in developing new sources for human embryonic stem cells and have vowed never to create a living animal through interspecies mixing.
But the work is still viewed as immoral by social conservatives.
“It is treating a human being at his or her earliest stages as a mere tool,” said Georgetown University philosophy professor Alfonso Gomez-Lobo, a member of the President’s Council on Bioethics.
“The destruction of such an organism does not change the moral wrongness of the initial action,” said Gomez-Lobo, who called the research “a violation of human dignity.”
Scientists say human cloning can help cure diseases, or at least help us better understand them. Extracting and observing the growth of stem cells from an embryo cloned from an ailing patient will give them unrivaled insight into how diseases develop.
The problem is how to obtain the eggs. Cloning is notoriously inefficient; only 3 percent to 4 percent of animal eggs used in cloning procedures result in live births, and no one has ever credibly reported cloning a human embryo. The field was thrown into turmoil in 2005 when Korean scientist Hwang Woo-Suk’s claim that he’d cloned a human embryo was exposed as a fraud.
And for a woman, donating eggs is a significant undertaking and requires taking hormone injections, which can be risky.
“You cannot in good faith justify women undergoing this procedure for no medical benefit,” Minger said. “These eggs for the most part are going to be wasted.”
Scientists have been successful in a handful of interspecies cloning projects involving closely related species, including creating a wild ox called a banteng in a cow’s egg.
But Cibelli, who will soon publish data in a scientific journal detailing his failure to clone monkey genes in a cow eggs, doubts the proposed experiments will work.
“It could be that we are doing something wrong,” Cibelli said. “But it looks like the farther apart the species are on the evolutionary tree, the harder it will be to clone.”
Copyright 2005 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
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