Many medical, ethical questions
The Korean researchers still have to get rid of some of the animal components used in producing the stem cells. Although the stem cells spontaneously differentiated into different types of body cells in the lab, the researchers still have to figure out how to control the process. Moreover, the stem cells from diseased patients would still contain the genetic coding for that disease.

Then there is the tangle of ethical questions surrounding embryonic stem-cell research in general. Some religious groups and their political allies are opposed to such research, saying that extracting the stem cells is akin to abortion because human embryos are killed in the process. They say the same medical objectives could be largely achieved using stem cells extracted from adults — a procedure that raises no moral objections.

Other ethicists favor using embryonic stem cells for regenerative purposes but fear that the research could open the way for creating cloned babies. Virtually all researchers agree that reproductive human cloning is either impossible or extremely undesirable, based on their experience with cloned animals.

South Korea's laws allow embryonic stem-cell research aimed at developing new therapies, but ban all research aimed at reproductive human cloning.

Are they embryos?
During a teleconference with reporters, Hwang argued that the two-dimensional blastocysts created in his lab shouldn't even be called embryos: "As you know, an embryo can be said as spermatozoa and oocyte [sperm and egg] fertilization, but there is no path to fertilization in our process ... I can say this result is not an embryo, just a nuclear transfer construct."

David Magnus, director of the Stanford Center for Biomedical Ethics, agreed: "Whatever these things are, they're not people."

Such a view is unlikely to placate critics, however. The critics as well as the supporters of embryonic stem-cell research are gearing up for a congressional debate over a bill that could open the way for the federal government to fund more experiments in the field.

U.S. Rep. Dave Weldon, a Florida Republican and physician, said the new research may hurt the chances for the bill, designated as H.R. 810. “This development will erode support for H.R. 810 in that it makes clear that they want to go beyond using IVF embryos and plan to create cloned human embryos for research,” Weldon said in a statement reported by Reuters.

H.R. 810 would not allow federal funding of studies like the one conducted by the Korean group, because the legislation specifies that the embryos have to be leftovers from fertility clinics.

Who will benefit?
Magnus and the Stanford center's associate director, Mildred Cho, raised another ethical issue in a Science commentary accompanying Hwang's research. Although they cited no fault in the South Korean project, they warned that research donors could be misled into thinking that they or their family members would personally benefit from new stem-cell lines.

They said it was "extremely unlikely" that the early research would result in cures. "Also, it is nearly certain that the clinical benefits of the research are years or maybe decades away," they wrote. Moreover, the women who provided only eggs for such experiments stood no chance of personally benefiting, even though the procedure for procuring the eggs posed a slight risk of pain, infertility or even death.

Hwang and his colleagues emphasized their stringent procedures for identifying volunteer donors and obtaining informed-consent forms — and Science published the actual forms as a supplement to the paper itself. None of the donors requested or received any payment for their participation, Hwang said.

Why it's significant
Harvard University's Douglas Melton, who has developed new stem-cell lines using test-tube embryos as part of a privately funded research project, said the South Korean research was significant for several reasons.

Read the research The journal Science is making the papers on the cloning research and ethical concerns, as well as a news story about the research, available over the Internet with free registration. Further resources: • Read the research

"The efficiency is much higher than people would have predicted," Melton told MSNBC.com.

He also said the creation of stem-cell lines that reflect genetic diseases was "exciting" because that would give researchers a new way to study the disease-causing genes in the lab — and potentially come up with remedies tailored to individual patients.

Melton marveled at how the South Korean government has been able to move so much more quickly than the United States through the regulatory considerations surrounding stem-cell research.

"While this nation has been struggling through the thicket of political and ethical issues, the Koreans have done it," he said. "They are now, hands down, the world leaders in this area."

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