A few years ago, therapeutic cloning looked like the future of medicine. It promised to realise the dream of repairing damaged tissues and organs using a patient’s own cells. But it also had a dark side: producing its supply of stem cells required the creation of human embryos which were later destroyed.

IN THE world of TV soap operas, it’s a familiar storyline. A brilliant but troublesome character who was written out of the script years ago makes an unexpected comeback, sending ripples of excitement through the community but also reopening old wounds.

Ethical concerns led the US to severely restrict funding for therapeutic cloning research. Then, in 2006, the problem magically disappeared. First the technique’s leading researcher, Woo Suk Hwang, was exposed as a fraud. Then a team in Japan reported success using a very different technique that did not require donated human eggs or the creation of embryos.

This is what makes the return of therapeutic cloning such a gripping plot twist (see “Human stem cells made using Dolly cloning technique”). Though it renews hope that the enormous potential of stem cells can finally be fulfilled, it also reopens the ethical quagmire.

That, in essence, is what happened in stem cell research this week, with the return of a technique called therapeutic cloning. What comes next should make for compelling viewing.

This article appeared in print under the headline “Back to the future of stem cells”

Will we now see a revival of the stem cell culture wars in the US? Probably, but they should be less polarised this time round. The Bush-era laws were relaxed by President Obama in 2009 to no great hullabaloo. The fact that the breakthrough work was done in Oregon may also help: home-grown success has a way of changing hearts and minds. What is clear is that we have entered a new phase in the long-running stem cell soap opera. Expect drama aplenty.

For a while this new method, using so-called iPS cells, was hailed as the future of medicine. But a series of setbacks has taken the shine off, and many researchers now doubt it will ever live up to its early promise.

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