A scientific milestone: Stem cells from skin

Scientists have made ordinary skin cells take on the chameleon-like powers of embryonic...

Scientists have made ordinary skin cells take on the chameleon-like powers of embryonic stem cells, a startling breakthrough that might someday deliver the medical payoffs of embryo cloning without the controversy.

Laboratory teams on two continents have reported success in a pair of landmark papers to be released on Tuesday. It’s a neck-and-neck finish to a race that made headlines five months ago, when scientists announced that the feat had been accomplished in mice.

The “direct reprogramming” technique avoids the swarm of ethical, political and practical obstacles that have stymied attempts to produce human stem cells by cloning embryos.

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Scientists familiar with the work said scientific questions remain and that it’s still important to pursue the cloning strategy, but that the new work is a major coup. “This work represents a tremendous scientific milestone — the biological equivalent of the Wright Brothers’ first airplane,” said Dr Robert Lanza, chief science officer of Advanced Cell Technology, which has been trying to extract stem cells from cloned human embryos.

There is a catch. At this point, the technique requires disrupting the DNA of the skin cells, which creates the potential for developing cancer. So it would be unacceptable for the most touted use of embryonic cells: creating transplant tissue that in theory could be used to treat diseases like diabetes and Parkinson’s or spinal cord injury.

But the DNA disruption is just a byproduct of the technique, and experts said they believe it can be avoided.

The new work is being published online by two journals — Cell and Science. The Cell paper is from a team led by Dr Shinya Yamanaka of Kyoto University; the Science paper is from a team led by Junying Yu, working in the lab of stem-cell pioneer James Thomson of the University of Wisconsin-Madison. Both reported creating cells that behaved like stem cells in a series of lab tests.

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Thomson, 48, made headlines in 1998 when he announced that his team had isolated human embryonic stem cells. Yamanaka gained scientific notice in 2006 by reporting that direct reprogramming in mice had produced cells resembling embryonic stem cells, although with significant differences.

The new work shows that the direct reprogramming technique can also produce versatile cells that are genetically matched to a person. But it avoids several problems that have bedeviled the cloning approach. It doesn’t require a supply of unfertilised human eggs, which are hard to obtain for research and require the women donating them to undergo a surgical procedure.

Using eggs also raises the ethical questions of whether women should be paid for them. In cloning, those eggs are used to make embryos from which stem cells are harvested. But that destroys the embryos, which has led to political opposition from President George W Bush, the Roman Catholic Church and others.