WASHINGTON (Reuters) - James Thomson knew it the moment he learned that a sheep named Dolly had been cloned from an adult sheep in 1996 -- the process of cloning can re-program a cell, allowing it to be transformed into any other cell.
Two years later, Thomson became the first to isolate and grow human embryonic stem cells, the body’s ultimate master cells. And on Tuesday, he led one of two teams that figured out how to transform ordinary cells into valued stem cells without using cloning technology or a human embryo.
“Dolly shows that, theoretically, any cell in your body can form a human being,” Thomson, a cell biologist at the University of Wisconsin in Madison, told reporters in a telephone interview.
This is because inside the nucleus, every cell in the body has all the instructions to make any other cell, or a complete organism.
Scientists have been struggling to learn why, if all the DNA is there, a damaged heart cell cannot simply regenerate itself in the way a salamander can grow new limbs and lizards can sprout new tails.
Cloning offered a way to understand this. By scraping the nucleus out of an egg cell and replacing it with the nucleus from another cell, the egg could be programmed to start dividing as if it had been fertilized by sperm.
Dolly’s birth, announced in 1997, sparked both wonder and revulsion. When scientists began trying to use this “somatic cell nuclear transfer” method in people, some politicians raced to block it.
But scientists wanted to understand what was going on inside these cells.
“It was clear that something in the egg was doing this,” Thomson said. “Prior to cloning, no one thought it possible to reprogram (a cell).”
“We really needed the information in the embryonic stem cells and these guys are getting it,” said Dr. John Gearhart, a stem cell expert at Johns Hopkins University in Baltimore.
SEEKING SHORTCUTS
Cloning technology was needed to understand the process but Thomson said the goal was always to bypass a tricky, expensive and inefficient technique.
“We weren’t avoiding the ethical controversy -- we just thought this was an alternative approach that would work quicker,” he said.
The goal was not to grow whole new people but to figure out how to get cells to go back to their own infancy, that early embryonic state, so they could grow anew, fresh and healthy.
By studying the cloned cells of animals and embryonic cells left over from fertility clinics, Shinya Yamanaka of Kyoto University in Japan and the University of California San Francisco found four key genes that would do it.
Independently, so did Thomson and his team at the University of Wisconsin.
The method is much easier to do than cloning and Thomson and Gearhart agreed that any good molecular biology lab can replicate it.
“I believe that these new results, while they don’t end that controversy, are the beginning of the end of the controversy,” Thomson 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.”
Editing by Will Dunham and Bill Trott
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