After outlandish claims, a few media circuses, and some near misses by legitimate researchers, a team of South Korean researchers reports the production of cloned human embryos. The findings, to be published today (February 12) in Science, were released Wednesday after a Korean newspaper broke an embargo (Science, DOI:10.1126/science.1094515, February 12, 2004).

Wook Suk Hwang and Shin Yong Moon of Seoul National University used somatic cell nuclear transfer to produce 30 human blastocysts and a single embryonic stem cell line; SCNT-hES-1. Using 242 oocytes and cumulus cells from 16 unpaid donors, the group achieved a cloning efficiency of 19 to 29%, on par with that seen in cattle (25%) and pigs (26%).

“They have obtained an efficiency that is really amazing,” said Hans Robert Scholer, a professor of reproductive medicine at the University of Pennsylvania. Although several groups have claimed to have grown cloned human embryos...

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