As a result, any tissue grown from the new stem cell could, in theory, be transplanted into the donor without much risk that the tissue would be rejected, Eggan noted.
But before the technique is viable, researchers must clear a technical hurdle: how to remove excess genetic information from the existing embryonic stem cell.
"Although the embryonic stem cells that we made contain the patient's genes, they also contain the embryonic stem cell genes that we started with," Eggan said. "And for the time being that's going to interfere with the usefulness of this."
The research team, led by Chad Cowan, merged human skin cells called fibroblasts with laboratory-grown embryonic stem cells.
The resulting hybrid cells contained chromosomes from both the skin cells and the stem cells. But according to several test results, the hybrid cells had the appearance, growth rate, and some key genetic characteristics of human embryonic cells.
"Even more importantly, we then went on to do experiments which really showed that their state had really been transformed to an embryonic state," Eggan said.
If future research can clear remaining technical hurdles, the approach "may circumvent some of the logistical and societal concerns surrounding" stem cell research, the Harvard team concludes in Science.
While the new technique requires an existing embryonic stem cell, the researchers hope to learn how to reprogram adult cells without the use of an embryonic cell in the first place.
"The real payoff ten years down the road perhaps, is to be able to directly induce those activities or factors of the adult cells and transform them to an embryonic state without having to use" an egg, Eggan said.
Free E-Mail News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES