With great fanfare a South Korean team announced last week that it had used therapeutic cloning to create human embryonic stem cells that were genetically matched to specific people. But their technique could already be obsolete.

Another team headed by Yuri Verlinsky of the Reproductive Genetics Institute, based in Chicago, claims to have produced patient-matched embryonic stem cells without resorting to therapeutic cloning. “It would be a much better approach,” he says.

Verlinsky says he has already created 10 embryonic stem cell (ESC) lines using his new “stembrid” technique. Unlike therapeutic cloning, it uses existing ESCs instead of human eggs, and so would be much cheaper and easier. What’s more, because no embryos are destroyed, it would bypass many ethical issues.

By Michael Le Page and Rowan Hooper

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