Inside the Korean Cloning Lab

The room is warm and still and nearly dark, bathed only in the light that leaks through its glass door. Refrigerator-size incubators, set to body temperature, line one wall. Along another wall, a young woman in a blue jumpsuit, mask and bonnet is peering through a microscope at half a dozen freshly harvested human eggs. With a glass pipette in one hand and a microneedle in the other, she braces one of the eggs against the tip of the pipette and, as if she were making a stitch, plucks at the membrane, creating a tiny opening. Resting the egg against the pipette, she uses the needle to gently squeeze the cell until the nucleus oozes out, like the center of a jelly doughnut. This is the sixth-floor lab in Building No. 85 at Seoul National University, the center of operations for Woo Suk Hwang, the South Korean scientist who made headlines last week when he announced that his team, using Dolly-the-sheep techniques, had created 11 human stem-cell lines perfectly matched to the DNA of human patients—a giant leap beyond anything any other lab has achieved. The eggs hollowed out in Building No. 85 were fused with skin cells taken from nearly a dozen patients—ages 2 to 56, suffering from a variety of injuries and disorders—and grown with unprecedented efficiency into early embryos lined with stem cells.

The development, published online by the journal Science, takes doctors an important step closer to creating custom stem-cell treatments for everything from Alzheimer's disease to severed spinal cords.

Hwang's methods are controversial, however—particularly in the U.S.—and the White House immediately criticized the experiment. The process is called somatic cell nuclear transfer (SCNT), but most people know it colloquially as therapeutic cloning. "I am very concerned about cloning," President Bush said in response to the news. "I worry about a world in which cloning becomes accepted." If Congress manages to pass a bill it is considering that would lift some of the restrictions on stem-cell research in the U.S., the President promised to veto it.

Scientists, for their part, were singing a different tune. "It's a tremendous advance," says Paul Berg, a Nobel laureate from Stanford University and a major backer of California's independent stem-cell initiative. "The Koreans' work is incredibly impressive," says Stephen Minger, director of the stem-cell biology laboratory at King's College, London. "It is fantastic—a major, major breakthrough."

The crux of that breakthrough is this: each of the newly created stem-cell lines is genetically identical to one of Hwang's patients.

That means any new tissue derived from that patient's cell line can be injected into that individual without triggering an immune reaction. If researchers can figure out how to fix the original defect, they may someday be able to generate replacement tissue that is custom designed to treat the patient's condition. Or at least that's the dream. No one knows yet whether those stem cells can be safely used in people.