Beyond the mirage of cell science

Opponents of therapeutic cloning, which uses cells from human embryos, say it amounts to murder because the embryos are destroyed in the process.

These embryonic stem cells can grow into all types of cells and tissues found in the body. Scientists say if they learn how to direct their growth, stem cells could be used to combat a host of intractable diseases.

Those who see a bright future for stem cells don't look to gene therapy but to in vitro fertilization (IVF) as a possible model. On July 25, 1978, Louise Brown became the first baby born using the then-controversial technique, in which conception takes place outside the womb. Critics called IVF unnatural, dangerous, and a threat to family life. But in the following quarter century, IVF has become widely used and accepted and now is considered a relatively safe medical procedure.

Ironically, IVF produces excess human embryos that clinics routinely destroy. Yet there has been little public outcry "because that technology is so popular that it would be political suicide to try to close in vitro fertilization clinics," says Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania in Philadelphia. There may be some 400,000 such embryos in clinics around the world.

The IVF experience suggests that religious and moral opposition to embryonic stem-cell research might fade only after it produces a useful therapy.

However hard it is to gauge the probability of success, many people are already weighing the costs of research against potential benefits. Besides California voters deciding whether to invest in stem cells, venture capitalists are backing a number of biotech firms. The lure of finding a miraculous healing agent makes the investment attractive.

"I can find no example where over the long term we have not moved ahead for research for cures of major diseases," says Dr. Blendon at Harvard. When people are polled about stem cells, he says, if the question mentions that the research might produce cures for well-known diseases, the number of people who say they support it zooms to a strong majority.

The potential for stem cells "is enormous," but there are countless twists and turns left on the path to harnessing them, adds Ann Parson, author of the new book "The Proteus Effect: Stem Cells and Their Promise for Medicine." "The amount of biology that we have to learn to turn that embryonic stem cell into a cell of one's choosing is huge. I personally wonder if it's not going to take one or two life times to see."

"There's a sort of idea in science that if you search long enough and hard enough, you'll find a solution to everything, especially in medicine," bioethicist Johnston says. "But that doesn't always pan out." She sees some parallels between the promise of stem cells and the search for an AIDS vaccine that after two decades remains undiscovered.

• Embryonic stem cells form in the first days after conception and eventually turn into all the cells, tissues, and organs in the human body. Scientists hope to use these in the treatment of a wide range of ailments.

• Adult stem cells - donated by humans - are extracted from bone marrow or umbilical blood and have been used to fight disease for many years.

• By one count, 24 countries have flexible or permissive laws on embryonic stem cells, including China, Russia, Japan, France, and the United Kingdom.

• In November, voters in Switzerland and California will vote on measures to regulate or support such research.

Source: William Hoffman

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