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Welcome to the age of cloning

International | BIOETHICS: After the South Korean breakthrough on human cloning, will the ethics be able to catch up with the science?

Issue: "Mel Gibson's passion," Feb. 28, 2004

It was bound to happen sooner or later. A team of South Korean scientists announced a breakthrough this month, one that takes human cloning beyond the realm of theory-and deep into the realm of controversy. For the first time, they successfully cloned human embryos to the blastocyst stage, the point at which they could have been successfully implanted into a womb. Then, instead of creating a baby, they destroyed the embryos to harvest their scientifically valuable stem cells.

Cloning has been controversial for years, but the science has generally lagged behind the debate. In previous cloning attempts, the embryos died after multiplying into eight or 10 cells. That level of development is far too early either to implant into a womb or to develop stem cells, those basic building blocks that turn into the multiplicity of human organs. Some scientists have even argued that there was a natural block in cloning humans beyond a handful of cells.

In their laboratories at Seoul National University, however, Woo Suk Hwang, Shin Yong Moon, and an American scientist, Jose Cibelli, found a way around that theoretical roadblock. They used very fresh eggs-and lots of them-from young volunteers, handled the eggs more carefully, and altered the timing of their cellular manipulations compared to earlier experiments. The result: 30 human embryos, each consisting of 100-150 multiplying cells.

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Fertility clinics routinely plant embryos of that size into the wombs of barren women, with a better than 60 percent chance of producing a child. But the Korean researchers were interested in producing something else: the stem cells that first appear at the blastocyst stage. Because they can be coaxed into producing many different types of body tissue, stem cells are seen as a sort of microscopic fountain of youth. In theory, they could produce perfect copies of worn or damaged cells to be transplanted without risk of rejection.

Some scientists tout such therapies as the cure for diseases ranging from diabetes to Alzheimer's. But their enthusiasm is far from universal. Leon Kass, chairman of the President's Council on Bioethics and an opponent of cloning, was dismayed by the Korean experiments. "The age of human cloning has apparently arrived," he said. "Today, cloned blastocysts for research, tomorrow cloned blastocysts for baby-making."

The Koreans insisted that was not the point. "We call for ... every nation to have a ban on reproductive cloning," said Dr. Moon at a Feb. 12 press conference in Seattle, where he discussed his experiment with a throng of reporters from around the world.

Thanks to Democrats in the Senate, the United States currently has no such ban. The House has twice passed a cloning ban, but the bill has bogged down in the Senate, where liberals want to forbid reproductive cloning but allow for so-called therapeutic cloning like that performed in South Korea.

Reproductive cloning vs. therapeutic cloning: It's a distinction that allows many people to reconcile their queasiness over creating life in a laboratory with their enthusiasm for ridding the world of death and disease. It would be wrong to make new life, the logic goes, but improving the life of others justifies whatever experimentation on a lump of cells may be necessary.

Pro-life ethicists strongly disagree. "To create a new human being with the intention of mutilating and destroying it can never be justified," said Patrick Cusworth of Life, a British pro-life group.

"Reproductive cloning is bad," agreed Dr. Helen Watt of England's Linacre Centre for Health Care Ethics, "but it does not have a 100 percent mortality rate, whereas in therapeutic cloning all the embryos die."

Indeed, despite the international scientific acclaim, the Korean breakthrough showed the high cost of therapeutic cloning. In their experiment, 16 women donated 242 eggs. The nucleus of each egg was removed and replaced by a nucleus from each woman's cumulus cells, which are cells that surround the egg. The cumulus cells apparently share something of the egg's replicating ability and so are the cells of choice for nucleus transfer in animal cloning.

Of the 242 eggs donated, the Korean scientists performed a nucleus exchange with 176. Of these, just 30 survived and grew into blastocysts. Out of 30 blastocysts, the scientists were successful in rendering only one stem cell line, suggesting that the others were genetically damaged. After harvesting the single line of stem cells, the researchers destroyed all 30 blastocysts -the fate of embryos that can never be transplanted into a human womb.

The breakthrough in South Korea is certain to ratchet up political pressure in the United States. Many pundits are attacking the limitations placed by President Bush on stem-cell research, mandating only that already-existing lines can be studied and that no more stem cells can be harvested from the embryos stored in the freezers of fertility clinics. Critics charge the strict research limitations put America's medical and technological leadership at risk.

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