Genetic alchemy: Skin cells ‘converted’ to stem cells

In fact, the new work could have great impact on Capitol Hill, where the Senate is poised to vote on legislation—already passed by the House—that would loosen President Bush’s restrictions on human embryonic research. Earlier this month, Senate Majority Leader Bill Frist, surprised many of his colleagues by announcing he would break with the president and support the Senate bill, which Bush has promised to veto.

Embryonic stem cells are capable of becoming virtually any kind of cell or tissue. Intensely studied around the world as the core of a newly emerging field of regenerative medicine, stem cells, it is hoped, can be used to grow new tissues to revitalise ailing organs.

In the Harvard researchers’ technique, the new stem cells are essentially rejuvenated versions of a person’s own skin cells, which means that the DNA in the new stem cells matches the DNA of the person who provided the skin cells. In theory, at least, any tissues grown from the new stem cells could be transplanted into the person to treat a disease without much risk that they would be rejected.

Although human embryonic stem cells have never been tested in humans, some researchers expect human clinical trials to begin within a year or so. Researchers caution, however, that like many other nascent therapies, stem cells might never live up to their promise.

The researchers also emphasise in their report that the technique is still far from finding an application in medicine because it involves a hybrid cell created from the fusion of a stem cell and an ordinary skin cell. While that cell has all the characteristics of a new embryonic stem cell, it contains the DNA of the person who donated the skin cell and also the DNA that was in the initial embryonic stem cell.

At some point before these hybrid cells are coaxed to grow into replacement parts to be transplanted into a person, that extra DNA must be extracted, the researchers write. The team describes this task as a ‘‘substantial technical barrier’’ to the clinical use of stem cells made by the new technique.

It is not clear whether the genetic reprogramming imposed upon the skin cells by the fused stem cells requires the initial presence of the stem cells’ DNA, or whether fluids in the initial stem cells can do the job themselves.

Still, it is fascinating, says John Gearhart, a stem cell researcher at Johns Hopkins Medical Institution, to see such good evidence that something in embryonic stem cells is able to turn an ordinary skin cell into the equivalent of an embryonic stem cell.

Even if the work does not lead directly to clinical applications, he and the Harvard researchers said, it is likely to boost the amount and quality of research into what stem cells really are and how they work. —LAT-WP