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John B. Gurdon (left) and Shinya Yamanaka will share the prize, worth about $1.2 million.

The two scientists who won this year's Nobel Prize in Physiology or Medicine discovered that cells in our body have the remarkable ability to reinvent themselves. They found that every cell in the human body, from our skin and bones to our heart and brain, can be coaxed into forming any other cell.

The process is called reprogramming, and its potential for new drugs and therapies is vast. If neurons or heart cells are damaged by disease or aging, then cells from the skin or blood potentially could be induced to reprogram themselves and repair the damaged tissue.

The winners — John Gurdon of the Gurdon Institute in Cambridge, England, and Shinya Yamanaka of Kyoto University in Japan and the Gladstone Institute in San Francisco — made their discoveries more than 40 years apart.

In 1962, Gurdon proved that a cell from a frog's stomach contained the entire blueprint to make a whole frog. When he took the cell's nucleus and popped it into a frog egg, the egg developed into a normal frog.

This method eventually was used to clone all sorts of animals, including cats, dogs, horses and, most famously, Dolly the sheep — the first mammal cloned from an adult cell. Gurdon, 79, continues to study reprogramming and was working in his lab when he received the call from the Nobel committee.

But a major obstacle stood in the way of further development of these stem cells: Getting the frog's stomach cell to strip away its specialization and turn into one of the 200 or so cell types known to exist in animals always required the use of an egg.

A question hung over the field for decades: Could a specialized cell reprogram itself all on its own?

Mattias Karlen/Courtesy of The Nobel Committee for Physiology or Medicine

Shinya Yamanaka discovered a simple recipe for converting skin from a patient into many different cell types, including nerve and heart cells.

In 2006, Yamanaka and graduate student Kazutoshi Takahashi found the answer, and it sent shockwaves through biology and medicine. They demonstrated that any cell could be reset and induced to develop into another cell type. And, even more remarkably, that it took little to get the job done.

Yamanaka and Takahashi took some cells from the skin of a mouse and then switched on four specific genes. After a few weeks, the cells stopped looking like skin cells and starting looking more like embryonic stem cells. That meant the cells could then be manipulated to develop into just about any cell Yamanaka wanted. He could even get the cells to form heart muscle that beat inside a Petri dish.

Yamanaka, 50, had essentially unlocked a cellular genie in the bottle. The discovery meant that a cell wasn't necessarily trapped in its fate to be, say, a skin, liver or heart cell. Rather, with the right instructions, a cell had the ability to strip away its specialization and become whatever cell the scientists chose. They called these new cells "induced pluripotent stem cells."

The landmark finding triggered thousands of studies. Researchers quickly wanted to learn how these new stem cells could be used to treat a vast array of diseases, such as Alzheimer's, muscular dystrophy and diabetes.

Although stem cell treatments for these diseases are still quite far away, the induced pluriopotent stem cells are turning out to be invaluable tools for studying hundreds of diseases. They can serve as a platform for screening drugs or for even simply testing how a patient will respond to a particular medicine.

The discoveries by Gurdon and Yamanaka have opened up a new era in personalized medicine, where each person's own cells may one day serve not only as a reservoir for fixing damaged tissue, but also as research tools for deciphering how diseases work inside each person's unique body.

Induced pluripotent stem cells also offer a possible alternative to human embryonic stem cells, which are controversial because they are obtained from embryos.

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[NPR 특집/쥐의 줄기세포에서 수정란 생성] Scientists Create Fertile Eggs From Mouse Stem Cells

 

Katsuhiko Hayashi

 

Each of these mouse pups was born from an egg scientists created using embryonic stem cells. It's possible the technology could change future treatment for human infertility.

Scientists in Japan report they have created eggs from stem cells in a mammal for the first time. And the researchers went on to breed healthy offspring from the eggs they created.

While the experiments involved mice, the work is being met with excitement — and questions — about doing the same thing for humans someday.

"Wow. That's my general reaction," said Hank Greely, a bioethicist at Stanford University who studies stem-cell science. "Repairing hearts, repairing brains, repairing kidneys, that's all good and important, and we'd all love to be able to do that. But this involves making the next generation."

Scientists obtain the versatile cells from embryos. Embryonic stem cells are controversial because researchers destroy the embryos to get them.

But because these stem cells can morph into any cell in the body, there's always been the possibility they could do something especially profound. They could offer a way to create eggs from anyone at any age. That could change how humans reproduce.

In this week's issue of the journal Science, Mitinori Saitou and colleagues at Kyoto University in Japan report they finally achieved that elusive goal.

"This is actually the first time to make eggs from embryonic stem cells and then produce eggs [that] become healthy offspring," Saitou said.

Moreover, Saitou's team did something potentially even more astonishing: They bred healthy mice from eggs made from another type of stem cell known as induced pluripotent stem cells.

These are cells that look essentially identical to embryonic stem cells. But instead of coming from embryos, they can be made from adult cells, such as skin or blood cells. So they don't have any of the ethical baggage of embryonic cells.

"They're gotten to what was our Holy Grail, which is making eggs," said George Daly, a leading stem-cell scientist at Harvard. "It's like cellular alchemy. I mean, they can turn lead into gold here. They can turn skin cells or blood cells into eggs."

The big question, of course, is whether anyone could do the same thing for people. No one knows for sure. And it would surely take a ton of work.

But John Gearhart, a stem-cell pioneer at the University of Pennsylvania, says mice are close enough to humans to think it's probably doable. "I think this will be worked out in time. I don't have any doubt about it," Gearhart said.

And if he's right, then, at the very least, it would be a huge advance for women who are infertile for medical reasons or who have postponed having babies too long.

"If we can make eggs from stem cells, then the biological clock isn't ticking so much for women," Stanford's Greely said.

But that could be just the beginning. The same team previously made sperm from stem cells. So, for example, the power to create sperm or eggs for anyone would be big news to many gay men and lesbians.

And Greely goes even further into territory charted by the book Brave New World. Combined with other techniques, eggs from stem cells could some day make it much easier for parents to pick babies with blue eyes or blond hair, or a talent for sports or music.

Speculation about the possibilities get even more sci-fi. "Any skin cell that you can find on the edge of a coffee cup theoretically could be induced back to being an egg, and a baby could be produced," said Ronald Green, a bioethicist at Dartmouth University.

"When you think about the commercial possibilities of people selling to infertile people babies produced from George Clooney or Jennifer Aniston, or whatever, you have to worry about it," Green said.

Now, it's important to remember that this may end up being nothing more than speculation. And even if it does prove possible, choices like these are probably decades away.

Even so, David Prentice of the Family Research Council says such research "cheapens all life in a way, not just embryonic or fetal life, but babies and the rest of us when we starting treating life as a manufacturing proposition."

But just the possibility is already stirring intense debate about where the power to use stem cells to make eggs might take us. "It's like any other technology," said Daniel Sulmasy, a professor of medicine and ethics at the University of Chicago. "Whatever we've done in human kind — whether it's discovering fire or creating the wheel — you can use these things to do lots of good and you can use them immoral ways," he says.