Scientists turn skin cells into stem cells

Scientists have found a way to turn ordinary human skin cells into cells that behave like embryonic stem cells, without using embryos.

Two teams, one in Japan led by Shinya Yamanaka and one in the United States led by James Thomson, published their results on 20 November.

How it works

The researchers added four genes to skin cells taken from adults. The genes reprogrammed the cells, turning back their development clock so that they could become almost any type of cell in the body.

The reprogrammed cells, known as induced pluripotent stem cells, appear to share most of the properties of stem cells taken from embryos.

Yamanaka's team announced last year that it had achieved the same result with cells from mice.

Why it matters

Stem cells have huge potential for medicine. Scientists hope they could be used to repair damaged tissue and treat diseases such as Parkinson's, diabetes and heart disease, and to study how diseases develop.

Until now, the most versatile stem cells have come from human embryos, which are destroyed in the process. That has made the research highly controversial, with religious groups and many politicians opposed to it.

The new technique avoids that problem, and could also make it possible to create stem cells that are genetically matched to a patient, so that they would not be rejected by the body.

A political impact

In the United States, President George W Bush has restricted federal funding for research on embryonic stem cells. The White House has welcomed the new findings.

Ian Wilmut, the British scientist who led the team that created Dolly the sheep, has said he will now focus on the new method instead of cloning embryos.

Caution

Scientists have warned that there is still a long way to go. Some of the genes used to reprogramme the cells are linked to cancer, and the viruses used to deliver them could cause problems. The cells will need to be studied in detail before they could be used in patients.

Many researchers say work on embryonic stem cells should continue, so that the two approaches can be compared.

But the discovery is being hailed as one of the most important in the field, and could change the direction of stem cell research around the world.