Image: Differentiated
This array of photomicrographs shows a variety of tissues that were produced from customized human embryonic stem cells. The stem-cell lines were isolated during a cloning process known as somatic-cell nuclear transfer.
By Alan Boyle Science editor

Information that came to light after publication of this study has led the researchers to request a retraction. Check MSNBC's Stem Cell Research section for updates.

Researchers in South Korea say they have created the first human embryonic stem-cell lines using DNA from injured or sick donors who could theoretically benefit from such cells.

The new cloning experiment, detailed in a paper published Thursday on the journal Science's Web site, builds on groundbreaking research that was published last year by the same group.

"This report brings science a giant step forward toward the day when some of humankind's most devastating diseases and injuries can be effectively treated through the use of embryonic stem cells," said the research team's leader, Woo Suk Hwang of Seoul National University.

However, the experiment also raises fresh ethical and regulatory questions about embryonic stem-cell research, just as Congress is preparing to take up the subject.

What stem cells do
Throughout the life of an organism, stem cells replenish the tissues that make up the body, ranging from bones and blood to brain cells. Embryonic stem cells show the most versatility, and scientists hope that such cells can someday be harnessed to repair severed spinal cords, heal damaged hearts, boost brain cells in Parkinson's disease patients and work other medical wonders.

An essential part of the dream is being able to tailor stem cells to reflect the genetic makeup of the patients themselves. Otherwise the new tissue might face rejection by the body into which it is transplanted. The new research represents a significant step in that direction — and also improves dramatically on the production process that has been pioneered by the Korean group.

Embryonic stem cells are extracted during the blastocyst stage — when the embryo is about the size of a grain of sand, comprising 100 to 200 cells in all. Typically, researchers take the stem cells from embryos that are left over from test-tube fertilization procedures, destroying the embryo in the process.

Hwang and his colleagues do not use surplus test-tube embryos to create their stem-cell lines. Instead, they employ a cloning technique known as somatic-cell nuclear transfer. In this process, the nucleus from an unfertilized donor egg cell is replaced with nuclear material from a different kind of cell. Then the egg is processed with electricity and chemicals, coaxing it to grow to the blastocyst stage.

Last year, the Korean group announced a single success: the creation of one stem-cell line after 242 tries. In that case, the same woman donated the egg as well as surrounding cells, known as cumulus cells, which were the source of the inserted nuclear material.

For the newly reported research, 18 women donated 185 eggs. Meanwhile, 11 donors, ranging in age from 2 to 56, donated abdominal skin biopsies that were cultured to provide the nuclear material for injection into the eggs. Nine of the skin donors had suffered spinal-cord injuries; one had juvenile diabetes; and one had congenital hypogamma-globulinemia, a type of immune-deficiency disease.

Video: Stem cell advance In 10 cases, the egg donors were not biologically related to the skin donors, while in the 11th case, a woman donated the egg as well as the skin. Eleven new stem-cell lines were created, based on genetic material from nine of the skin donors.

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"A year ago, the world was stunned when Professor Hwang announced that out of 242 eggs, they were able to establish one stem-cell line. Now the great news is that 16 times fewer women would be called upon to donate for this type of research," said Gerald Schatten, a co-author of the Science study and director of the Pittsburgh Development Center at the Magee-Womens Research Institute.

What's more, lab-culture tests indicated that the stem cells would be immunologically compatible with the skin donors. If the process could be perfected, the healthy cells could be transplanted safely into the spinal-cord patients. But that's a big "if."

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.

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

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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