By Karl Ritter

and Malcolm Ritter

Associated Press

NEW YORK — Two scientists from different generations won the Nobel Prize in medicine Monday for the groundbreaking discovery that cells in the body can be reprogrammed into completely different kinds, work that reflects the mechanism behind cloning and offers an alternative to using embryonic stem cells.

The work of British researcher John Gurdon and Japanese scientist Shinya Yamanaka — who was born the year Gurdon made his discovery — holds hope for treating diseases like Parkinson’s and diabetes by growing customized tissue for transplant.

And it has spurred a new generation of laboratory studies into other illnesses, including schizophrenia, which may lead to new treatments.

Basically, Gurdon, 79, and Yamanaka, 50, showed how to make the equivalent of embryonic stem cells without the ethical questions those very versatile cells pose, a promise scientists are now scrambling to fulfill.

Once created, these “blank slate” cells can be nudged toward developing into other cell types. Skin cells can ultimately be transformed into brain cells, for example.

Just last week, scientists reported turning skin cells from mice into eggs that produced baby mice, a possible step toward new fertility treatments.

Gurdon and Yamanaka performed “courageous experiments” that challenged scientific opinion, said Doug Melton, co-director of the Harvard Stem Cell Institute.

“Their work shows … that while cells might be specialized to do one thing, they have the potential to do something else,” Melton said. It “really lays the groundwork for all the excitement about stem cell biology.”

Another Harvard stem cell researcher, Dr. George Daley said he didn’t think anybody was surprised by the award announcement. “The fact that these two share it together is inspired.”

In announcing the $1.2 million award, the Nobel committee at Stockholm’s Karolinska Institute said the work has “revolutionized our understanding of how cells and organisms develop.”

Gurdon showed in 1962 that DNA from specialized cells of tadpoles, like skin or intestinal cells, could be used to clone more tadpoles. In 1997, the same process led to the cloning of Dolly the sheep, showing it would also work in mammals.

Gurdon told reporters in London that at the time of his discovery, it had “no obvious therapeutic benefit at all. It was almost 50 years before the value — the potential value — of that basic scientific research came to light.”

Forty-four years after Gurdon’s discovery, in 2006, Yamanaka and his team moved beyond tadpoles. They showed that a surprisingly simple recipe could turn mouse skin cells back into primitive cells, which in turn could be prodded into different kinds of mature cells. The work was later repeated with human cells.

In theory those primitive cells are “blank slates” — like embryonic stem cells that can be turned into any cell in the body.

Turning a skin cell into a stem cell takes weeks in a lab. Scientists introduce two to four genes that turn the cell’s own genes on and off. It’s a little like rebooting a computer, changing the cell from running the collection of genes that make it a skin cell into using another set that make it a stem cell.

Gurdon, who said his ambitions to become a scientist were dismissed as “completely ridiculous” by his headmaster when he was in his teens, has served as a professor of cell biology at Cambridge University’s Magdalene College. He is currently at the Gurdon Institute in Cambridge, which he founded.

Yamanaka worked at the Gladstone Institute in San Francisco and Nara Institute of Science and Technology in Japan. He is currently at Kyoto University and also affiliated with the Gladstone Institute. Yamanaka is the first Japanese scientist to win the Nobel medicine award since 1987.

Asked how he planned to celebrate, Gurdon said he was invited to drinks at 6 o’clock. “I intend to attend those drinks,” he said dryly.

Yamanaka told Japanese broadcaster NHK that he was at home doing chores on Monday when he got the call from Stockholm.