Cloning Gets Closer

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k when it was no more than a cheesy science-fiction plot device, human cloning seemed like something that would eventually be revealed to a horrified world full-blown and fully grown — a monstrous carnival apparition ("The Amazing Cloned Boy!") out of a medical freak show.

It hasn't quite turned out that way. Cloning has been emerging gradually, over the past decade, in small increments. Each advance has been startling enough, prompting ethical debates, cautionary references to Aldous Huxley's brave new world and calls for restrictive legislation. But there have been so many milestones, starting even before the birth of Dolly the sheep in 1996, that each one seems a little less startling than the one before. Sometimes an advance is so subtle that it sounds just like the breakthrough that made headlines the year before.

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That's how a report in the journal Science sounded last week — at least at first blush. Woo Suk Hwang and Dr. Shin Yong Moon, from Korea's Seoul National University, announced that they had created more than 200 embryos by cloning mature human cells and had grown 30 of them to the blastocyst stage of development, each more than 100 cells strong. This isn't the first time cloned human embryos have been produced: in 2001 the Massachusetts biotech firm Advanced Cell Technology made several. They all died quickly, but in a sense the first cloned human cells are actually old news.

Still, two things make the Korean experiment more than a little noteworthy. The first is simply that their embryos didn't die. That's a very big deal; many experts were convinced that human clones would be impossibly fragile. Second, the scientists extracted embryonic stem cells from the blastocysts and coaxed some of them into a self-perpetuating colony.

That could ultimately prove to be an even bigger deal. Embryonic stem cells are the unspecialized raw material that give rise to every cell type in the body — in fact, some of Moon and Hwang's stem cells evidently turned into bone, muscle and immature brain cells. If scientists can learn to control their development, stem cells could in theory supply replacement tissues to treat any ailment involving cell damage — and there are plenty, including heart disease, diabetes, spinal-cord injury, Parkinson's and Alzheimer's. "Our goal," said Hwang during a press conference at a meeting of the American Association for the Advancement of Science in Seattle last week, "is not to clone humans, but to understand the causes of diseases."

That disclaimer didn't satisfy critics. Indeed, the Korean breakthrough adds fuel to two different ethical debates at once. The first — whether cloning for reproduction should be allowed — is pretty well settled. Only a handful of loose-cannon scientists and members of the Raelian sect, who believe humans were created by aliens, openly favor human cloning. It is explicitly banned in many countries, including Korea.

But the debate over stem-cell research, whether those cells come from cloning or from conventional in-vitro fertilization, is far from over, at least in the U.S. Right-to-life and religious groups, including the Roman Catholic Church, believe that human life begins at conception and thus that harvesting stem cells is tantamount to murder. With views like that on one side and high-profile advocates like Christopher Reeve and Michael J. Fox touting the benefits of therapeutic cloning on the other, the Bush Administration has tried to split the difference. In August 2001 the President declared that the U.S. government would fund stem-cell research — but only using stem-cell lines that had already been isolated.

Only a dozen or so such lines have proved useful, which most American scientists consider far too few to work with. They can still tap a much more limited pool of private funding, but a bill introduced in the Senate last year would have hamstrung them further by banning human cloning even for therapeutic purposes. If that law had passed and the Koreans had done their work in the U.S., said Donald Kennedy, editor in chief of Science and a participant in last week's press conference, "they would have been jailed."

By rejecting a watered-down bill that would have banned reproductive cloning only, conservatives have ensured that the U.S is, bizarrely, one of few developed countries that doesn't forbid human cloning. Responsible scientists wouldn't try it, but an unethical researcher could read the Science paper and attempt to use the technique to bring a clone to term. "I'm afraid that some nitwit is going to try," says Larry Goldstein, a cellular and molecular biologist at the University of California at San Diego. But given the high rate of spontaneous abortions and genetic defects seen in other species, it's not likely to work. The Science paper is a recipe for cloning, said Kennedy, "only in the sense that 'catch a turtle' is the recipe for turtle soup." Said Hwang: "In my humble opinion, it's not so easy to mimic our technology."