What Comes Next?
Scientists are now grappling with a major setback to stem cell research
Snuppy turned out to be a real cloned Afghan hound. But the rest of the news out of South Korea last week was a bitter disappointment to people counting on cloning to advance stem cell research. Investigators probing Hwang Woo Suk's work at Seoul National University announced that his team had never extracted stem cells from a cloned human embryo, dashing hopes that medical researchers might be anywhere close to testing treatments--and sending scientists scrambling to figure out where the research really stands.
The promise held out by the breakthroughs Hwang reported, in two papers published in 2004 and 2005 in the journal Science, was that doctors might someday be able to heal people with spinal cord injuries or genetic diseases by inserting replacement cells perfectly matched to their own tissues. Embryonic stem cells, which Hwang announced he had harvested from cloned embryos in the 2004 paper, have the ability to turn into any cell type in the body. And when the stem cells come from embryos cloned from patients, as he claimed to have accomplished in the 2005 paper, they should be able to be transplanted safely. That research was discredited in December, although it appears he managed to clone some sickly human embryos. He apologized publicly late last week, claiming that junior researchers had misrepresented their progress to him and that, with six more months, he could create patient-matched stem cells. Snuppy, in the end, was Hwang's one real achievement of the past two years.
Next steps. The news, while a big setback for stem cell research, won't spell its demise. Already, scientists who thought they had been left in Hwang's dust are rethinking their next steps. Two years ago, scientists at Advanced Cell Technology, a biotech company in Worcester, Mass., were within months of getting stem cells from a cloned embryo, according to medical director Robert Lanza. When Hwang published his article, funding dried up and "we went into a financial nose dive,"he says. Now, Lanza is preparing to pick up where he left off. British researcher Alison Murdoch's team at Newcastle University had been focused on developing techniques to get stem cells from cloned embryos to patients; now they are emphasizing research on basic cloning. "We're going back to 'Will it actually work in humans?'"
And Hwang's team was working on only one way of getting stem cells; progress continues on other fronts. The South Korean researchers were trying to extract cells from embryos cloned to match a patient's DNA by replacing the nucleus in an egg with that from a patient's skin cell. Most researchers extract cells from embryos made the old-fashioned way. When couples go through in vitro fertilization, they routinely have extra embryos made. A few are transferred to the uterus, and the rest are frozen. They'll be used in later IVF cycles, given away, discarded--or donated for research.
Granted, Hwang's approach is the more medically promising. The disadvantage of stem cells from IVF embryos is that they aren't matched to any patient. Cloning allows researchers to make stem cells that, in theory, could be injected--to become neurons or heart muscle cells, for example--without fear of rejection. On the other hand, if enough stem cells were made from different IVF embryos, it might be possible to find matches for patients in the way bone marrow and organ recipients are matched to donors now. Another advantage of stem cells from cloned embryos: They could be used to model diseases. If a patient with Parkinson's donated skin to make embryonic stem cells, the resulting cell line could be used to study the disease and test drugs.
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