From Scientific American:
As Dolly matured, the cloning technology that created her—called somatic cell nuclear transfer (SCNT)—grew into a rich research enterprise. Scientists hoped to eventually be able to take a patient’s cell, place its nucleus into an unfertilized human egg and then harvest embryonic stem cells to treat intractable conditions such as Parkinson’s disease. But the first human clinical trial continues to seem remote, with embryonic cloning constrained by a federal funding ban, deeply controversial ethical issues and technical challenges. In mid-May safety concerns led the U.S. Food and Drug Administration to put on hold a bid by Geron Corporation in Menlo Park, Calif., to conduct trials on patients who have acute spinal cord injury.
Now the 64-year-old Wilmut is one of several high-profile scientists who remain loyal to SCNT in concept but are leading a wholesale charge out of the field and into an alternative technology. That other approach, first demonstrated in 2006 by Shinya Yamanaka of Kyoto University, restores adult cells back to an embryoniclike state called pluripotency, in which they regain the ability to develop into any kind of cell. Any well-appointed lab can apply the comparatively straightforward technique. “It’s really easy—a high school lab can do it,” says Mahendra Rao, who heads up the stem cell and regenerative medicine business at Invitrogen, a life sciences corporation based in Carlsbad, Calif. Yamanaka’s approach also enables scientists to leap over nuclear transfer’s egg supply problems and sidestep qualms about destroying human embryos.