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Anti-cloning protest: environmental groups hit out against the Kyunghee human cloning experiments. Credit: AP/AHN YOUNG-JOON

A South Korean research team, which announced last week that it had cloned a human embryo, has been criticized by other researchers for refusing to disclose the evidence to back up its claim.

Indeed, many doubt whether the cloning experiment, claimed to be the first to have produced an embryo from a human somatic cell, has produced promising results.

Researchers from Kyunghee University Hospital in Seoul announced at a press conference that they had cultivated an early-stage embryo using an unfertilized egg and a somatic cell from a female patient who had been receiving infertility treatment there.

The team, led by Kim Seoung Bo and Lee Po Yon, professor and associate professor in obstetrics and gynaecology at Kyunghee University, injected nuclei from granulosa cells (differentiated cells that surround the oocyte) into enucleated oocytes.

Of six fertilized eggs, one divided to the four-cell stage. Researchers say they then destroyed this ‘embryo’ without implanting it into a human body. They say they adapted the technique used by researchers from the University of Hawaii, who have cloned several generations of mice using granulosa cells (see Nature 394, 369–373; 1998).

“The experiment was carried out purely for the purpose of medical research, and not for clinical purposes. The fertilized egg was not implanted in the uterus of the donor, as we have no intention of creating a cloned baby,” said Lee at the press conference.

Lee says the experiment was conducted according to ethical rules on artificial fertilization laid down by the South Korean Medical Association in 1993, which prohibit the implantation of genetically engineered human embryos. The government is compiling a draft bill on the regulation of human cloning research, which is expected to pass the congress early next year.

Although the research team has no plans for any further experiments until the new legislation is ready, it hopes to use the technique to develop cells and tissues for replacement therapy and to treat infertility.

But there is widespread concern among the public, even though the experiment stopped short of producing a full human clone. The Korean Federation for the Environment Movement, for example, says human cloning research, if misused, could result in a “great mishap to all mankind”.

There was a more muted response from the scientific community in South Korea, with some doubting its success, as no evidence has been released.

“The lack of a scientific presentation leads us to think that their results are not ‘hair raising’ in terms of a scientific breakthrough,” says Dae-Young Uhm, associate professor in physiology at Sungkyunkwan University. “The only notable social response was from the civil rights groups.”

Kim refuses to release evidence of the experiment's success to avoid further controversy. “We have strong evidence, including photos, but we will not release it now as we believe our reputation has been damaged enough,” he says.