more ethically appealing than an alternative approach that requires cloning.
Two separate teams of researchers say they have sidestepped the
cloning method and reprogrammed mature human cells into a primordial,
embryonic-like state. Those cells were then transformed into other tissue types, such as heart cells. The long-term hope is that such freshly-created tissue may, for example, be used to heal a heart-attack patient. Unlike cloning, "the wonderful thing about this approach is that it's easy."
There are several limitations to the current approach. For now, both teams had to use dangerous viruses to effectively transport the genes into the cell, which could have deadly consequences if it was immediately applied to humans. Dr. Yamanaka and others say they are testing other viruses in the hopes of finding a non-harmful one.
And before the reprogramming technique can be applied to human patients, it needs to be tested on large animal models to ensure that it's safe and effective.
Still, the latest results are a big step up from similar breakthroughs in mice, separately reported this summer by Dr. Yamanaka's group and two other research teams in the U.S. The Kyoto team reported that embryonic-like cells developed with the new technique could even help form a new mouse -- a gold-standard test for the viability of the created tissue.
UPDATE: "I believe that these new results, while they don't end that controversy, are the beginning of the end of the controversy," James Thomson Thomson, a cell biologist at the University of Wisconsin in Madison (on one of two teams that did the work), said.
One first step may be to grow tissue transplants to repair a damaged heart, replace the brain cells destroyed by Parkinson's disease, or perhaps even to grow another whole organ.
But the ultimate goal is even more ambitious. "From a heart cell we don't have to go back to an embryonic stem cell," Gearhart said in a telephone interview.
"We could go back to a cardiac progenitor cell. If we knew the right combination of things ... we could be instructing our own cells to get them to do what we want them to do."