The successful cloning of human embryos by a South Korean team has alerted Western researchers to the pace of scientific and technological progress in East Asia, biologists say.

A team led by Woo Suk Hwang and Shin Yong Moon of Seoul National University last week revealed that they had grown the first embryonic stem-cell line derived from a cloned human embryo (W. S. Hwang et al. Science 10.1126/science.1094515).

Although the lead researchers are already renowned in their own country for their cloning and stem-cell work, the result has highlighted research in nations such as South Korea and Singapore. “Asian workers are likely to be major players in this field,” predicts stem-cell pioneer Roger Pedersen of the University of Cambridge, UK.

Hwang and Moon attribute their success to a supportive cultural environment, well-funded laboratories, and legislation that permits the cloning of human embryos for research.

Hwang adds that the rarity of organ donation in South Korea lends impetus to research that might create alternative sources of transplant tissue. The work ethic in the labs also helps, he says: “There is no Saturday, no Sunday and no holidays,” he told the annual meeting of the American Association for the Advancement of Science (AAAS) in Seattle on 16 February.

Critical to the researchers' success was their collection of 242 eggs from 16 female volunteers, with which they fine-tuned the tricky cloning method. They injected the nucleus from one of the cumulus cells that nestles around a woman's eggs into an egg that had been stripped of its genetic material. About a quarter of the embryos grew into blastocysts, and the team extracted and grew embryonic stem cells — which can generate many different tissues — from one of these.

While lauding the advance, some at the AAAS meeting said that the pace of human therapeutic cloning research in Asia and elsewhere threatens to leave US scientists stranded, as they cannot get federal funds to derive stem cells from human embryos.

But some US biologists say that they can contribute to the field by collaborating with researchers in South Korea, Britain and other countries where the work is supported. “We should behave in a complementary manner,” says Gerald Schatten, who studies primate cloning at the University of Pittsburgh. “We don't have to do everything in every country.”

The cloning breakthrough has revived public debate in the United States on whether such research should be taking place. There is no US legislation on human cloning because of a stalemate between those who want to outlaw all forms of human cloning and those who want to ban reproductive cloning but allow therapeutic cloning. Because the question is linked to abortion, it could well emerge as an issue in this year's presidential election campaign, specialists at the meeting said.