Much like the sinister Nazgûl in the Lord of the Rings, the spectre of fraudster Hwang Woo-suk hovers over stem cell research. This time his chilling shadow fell on its most recent star, Japanese researcher Shinya Yamanaka. Yamanaka become a key player almost overnight with a series of stunning papers showing that it was possible to create embryonic-like stem cells without destroying embryos. His work may make embryonic stem cell research a dead end, say its opponents. And enthusiasm for his induced pluripotent stem cells (iPS cells) is growing by the day in laboratories around the world.

However, it seems that in his haste to publish results, Yamanaka made a couple of small mistakes in his latest paper, published online on February 14 in the journal Science. Two weeks later, an anonymous email was sent to journal editors, science journalists and scientists pointing out the errors. Someone called “Reprogrammer Yamanaka” pointed out “embarrassing inconsistencies” and insisted that his team “either retract their paper or provide meticulous and thorough new analysis”.

Had the Nazgûl stabbed Frodo? It seems not, says Nature in a recent editorial. “Happily, he has since given plausible explanations for the mistakes, and has effectively argued that they do not affect the article’s central conclusion -- thus heading off worries (and one unsubstantiated accusation) that the errors signalled deeper problems with the article.”

In fact, the cold breath of the Korean ringwraith might have cheered scientists threatened by Yamanaka’s technique. If it succeeds, they may not be to muster the PR power to convince a sceptical public to authorise and fund therapeutic cloning. Stem cell scientist Alan Trounson, wrote in Nature Reports Stem Cells that many journalists were already asking: "Isn't the California Institute of Regenerative Medicine (CIRM) out of business now that the Yamanaka and Thomson papers show human fibroblasts can be induced to pluripotency?" He responded cheerily that embryonic stem cells remain the “gold standard” in all stem cell research. And the president of the International Society for Stem Cell Research, George Daley, recently declared, “There will never be a time when we don’t need human embryo research.”

However, not all of his colleagues feel the same way. In a Nature article which was aimed at stripping iPS cells of their glamour, the scientist who first isolated human embryonic stem cells, James Thomson, of the University of Wisconsin, foresees the end of an era. “If you can’t tell the difference between iPS cells and embryonic stem cells, the embryonic stem cells will turn out to be an historical anomaly,” he says. ~ Nature, Mar 27; Nature Reports Stem Cells, Jan 24; Alameda Times Star, Mar 20