The Future of Stem Cells

Disease Research Hindered by Reproductive Cloning Threat, Experts Say

From the WebMD Archives

July 8, 2004 -- Stem cell research is one thing. Cloning human babies is another. Yet the two issues are so mixed up, we risk the worst of both worlds.

Research into stem cells may provide treatments for terrible medical ailments. The list includes Alzheimer's and Parkinson's diseases, cancer, and spinal paralysis. That's why Nancy Reagan, Michael J. Fox, and Christopher Reeve all are outspoken advocates.

There are all kinds of stem cells. But the ones from which we can learn the most are the cells that make up an early human embryo. They're formed in the first 14 days after a human egg is fertilized by sperm or when a human egg has its own DNA replaced by DNA from an adult cell.

Scientists call this latter technique somatic cell nuclear transfer or SCNT. It's also the first step in cloning. And there's the rub. If a SCNT-created embryo is implanted in a woman's womb, it might become a cloned baby genetically identical to the DNA donor. Does stem cell research necessarily put us on the slippery slope that leads to reproductive cloning?

No, argues Carol A. Tauer, PhD, of the Center for Bioethics at the University of Minnesota, Minneapolis. Writing in the July 10 issue of The Lancet, Tauer says that stem cell research and reproductive cloning are totally separate issues.

Mixing them up, she says, is a terrible mistake. On the one hand, fear of human cloning might shut the door on the promise of stem cell research. And on the other hand, the confusion makes it very hard to pass a law almost everybody wants: a ban on reproductive cloning.

"Although there is agreement that it is good to prohibit cloning for reproduction, there is no agreement on whether cloning should be prohibited for treatment research," Tauer tells WebMD. "When these two issues are put together, it makes it impossible to pass any laws."

Tauer advises the U.S. government -- and the U.N. -- to consider the issues separately.

"One thing should be done at a time," she says. "Congress should take cloning for reproduction -- on which there is wide agreement -- and get that passed. And then they should look separately on the issue of whether federal funding should be extended to stem cells and cloning for research. People on both sides may not want to agree with me. But I think if we agree on one thing, why not take care of that -- both in the U.S. and also at the level of the U.N. -- and then look at other issues."

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Deliberate Confusion

That's not likely to happen, says Arthur Caplan, PhD, director of the center for bioethics at the University of Pennsylvania, Philadelphia.

"Of course the issues should be separate," Caplan tells WebMD. "But as sensible as this seems to be, the critics of stem cell research see that to split the issues is to lose the debate. Many of those who support a total ban on cloning would back off if reproductive cloning were off the table. It is specifically mixed up by those who are critical of stem cell research. They want to fuzz the line because that is their best bet to ban everything."

Buried in the debate is an ethical issue. That's the question of whether the collection of human cells known as a blastocyte is a human being. If the blastocyte is healthy -- and many blastocytes formed by SCNT are flawed -- and if it is transferred into a human womb, it might grow into a fetus, though it's unlikely.

One argument advanced by some abortion opponents is that a woman's egg is a human being from the moment it is fertilized. Banning research on stem cells -- particularly on human blastocytes, even if they've never been placed in a woman's body -- might set a legal precedent for banning abortion.

"Opposition to abortion is the 900-pound monster hiding behind this confusion of stem cell research with reproductive cloning," Caplan says. "They think that if we're all frightened enough about cloning people, they can get legislation saying that embryos are human from the moment of conception. That would help them get a ban on abortion."

Cloning and Stem Cell Research

Can stem cell research proceed without cloning? Yes and no, says Alta Charo [SHARE-row], JD, professor of law and medical ethics at the University of Wisconsin, Madison.

"Cloning is something that is not essential to stem cell research," Charo tells WebMD. "Most research will go on with discarded embryos from reproduction assistance clinics."

But some important research will require the use of cloning techniques, although there might be less confusing ways to talk about it.

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"It might help to get away from the issue of cloning and talk about the deliberate creation of special embryos," Charo says. "There will be a small number of experiments that cannot be done with discarded embryos. Those are the experiments that look at the genetic mechanisms of the causes of disease."

If that seems vague, Charo has a specific example: breast cancer. Two genes, BRCA1 and BRCA2, give a woman a very, very high risk of breast and ovarian cancer.

"Their alternatives are awful: We can rip out their ovaries and throw them into early menopause. We can cut off their breasts. Or we can wait and watch to see whether they develop cancer," Charo says. "The better thing is to understand what is going on to make this mutation cause cancer."

Using SCNT, cells from a woman carrying the BRCA mutation could be used to create an embryo carrying the mutation. From this embryo, scientists could obtain stem cells. And from these stem cells it would be possible grow laboratory cultures of ovarian and breast tissues.

"Now you can find out why this is causing cancer," Charo says. "And this gives you an opportunity to disrupt this sequence of events. Now you are on the way to an intervention that doesn't require mutilation of women's bodies. This you cannot do with discarded embryos."

The Politics of Stem Cells

Federal laws regarding stem cells appear to be in a stalemate. But several states are seizing the initiative.

"Stem cell people are being successful," Caplan says. "They have swung opinion in California, New Jersey, and Massachusetts in favor of stem cell research. In those places, talk about cloning research has gone into the back seat."

Indeed, California is about to vote on Proposition 71, which would generate $3 billion for stem cell research.

Why? Money, say Caplan and Charo. With an eye to the future, states see the opportunity to attract biotechnology companies.

"States are beginning to recognize there is a tremendous economic opportunity in terms of an edge in the biotech sector," Charo says. "So I think people who are middling on abortion issues are being moved to support stem cell research on cells from embryos that are going to be discarded any way. They don't want to be left behind."

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Politics being what they are, there won't be any movement on stem cell legislation until after the November 2004 elections. But that doesn't mean nothing is happening.

Charo notes that the National Academy of Sciences and the Institute of Medicine are developing strict guidelines for stem cell research. The prestige of these institutions is such that their recommendations are very likely to influence the review boards that oversee medical research.

"These guidelines will go beyond the issue of [where stem cells come from] and go into what experiments you should do and not do," Charo says. "This gives the review boards the opportunity to say, can you do this with animals? If it has to be done with human embryos, can it be done with discarded embryos? You can make sure people do not leap to the most controversial method of using stem cells without exploring other issues. This does offer the public reassurance that scientists aren't doing something because it is fashionable, that science is not being done frivolously, but because there is no other way to do it."

WebMD Health News

Sources

SOURCES: Tauer, C.A. The Lancet, July 10, 2004; vol 364: pp 209-214. Carol Tauer, PhD, emeritus professor of philosophy, The College of St. Catherine; visiting professor, Center for Bioethics, University of Minnesota, Minneapolis. Arthur Caplan, PhD, director, Center for Bioethics, University of Pennsylvania, Philadelphia. Alta Charo, JD, professor of law and medical ethics, University of Wisconsin, Madison.
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