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Human skin ‘reprogrammed’ to form stem cells

At last, a milestone in stem-cell technology has been reached that could enable patients to be treated with new tissues made from their own cells.

Crucially, the tissues can be generated without having to extract cells from human embryos, a major ethical objection that has obstructed stem cell research until now.

One team in Japan, and another in the US, have independently shown it is possible to produce embryonic-like stem cells directly from a patient’s own skin cells without having to create and destroy a cloned human embryo first. Dolly, the most famous sheep in the world, was created using the embryonic method.

Instead, they simply exposed human skin cells to four natural gene switches, called transcription factors. Both teams successfully used these to reprogramme skin cells in a lab dish into cells resembling embryonic stem cells, which have the ability to turn into any tissue of the human body.

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Both teams used viruses to insert four genes comprising the transcription factors into skin cells, and demonstrated that brain, heart and other tissues could be created from cells created this way.

Virus hurdle

“We are now in a position to be able to generate patient- and disease-specific stem cells, without using human eggs or embryos,” says Shinya Yamanaka of the University of Kyoto, who led the Japanese team. “These cells should be useful in understanding disease mechanisms, searching for effective and safe drugs, and treating patients with cell therapy.”

For these cells to be as useful as embryonic stem cells, “we have to find a way to avoid retroviruses before application in cell therapy”, Yamanaka says, as they could result in tumours.

The US team, led by James Thomson of the Genome Center of Wisconsin in Madison, reported their breakthrough in the journal Science.

‘Scientific milestone’

“This work represents a tremendous scientific milestone,” says Bob Lanza, chief scientist at Advanced Cell Technologies in Massachusetts, US. “But this isn’t over by a long shot. It’s extremely important to temper the excitement with caution.”

Lanza says success will depend on be finding alternative ways to create such cells&colon; “The FDA would never allow us to use these virally modified cells in patients.”

“Having two ways to re-programme might help us understand how reprogramming works,” adds Robin Lovell-Badge of the National Institute of Medical Research in London. “But we should be careful not to abandon embryo research altogether. It’s always best to keep all avenues of research open to maximise chances of success.”