EARLY STAGES
The science of iPS cells is still in early stages. Among concerns is the fear that implanted cells could grow out of control and develop into tumors.
Some scientists say stem cells from embryos may prove more useful against disease than iPS cells, and the ethics of working with embryos should be defended.
Nevertheless, since Yamanaka published his findings the discoveries have already produced advances. The techniques are being used to grow cells in laboratories to study disease, the chairman of the awards committee, Urban Lendahl, told Reuters.
"You can't take out a large part of the heart or the brain or so to study this, but now you can take a cell from, for example, the skin of the patient, reprogramme it, return it to a pluripotent state, and then grow it in a laboratory," he said.
"The second thing is for further ahead. If you can grow different cell types from a cell from a human, you might - in theory for now but in future hopefully - be able to return cells where cells have been lost."
Thomas Perlmann, Nobel Committee member and professor of Molecular Development Biology at the Karolinska Institute said: "Thanks to these two scientists, we know now that development is not strictly a one-way street."
"There is lot of promise and excitement, and difficult disorders such as neurodegenerative disorders, like perhaps Alzheimer's and, more likely, Parkinson's disease, are very interesting targets."
For now, both men said their scientific work continues.
Asked why he still keeps his schoolteacher's discouraging report, Gurdon said: "When you're having problems, like when an experiment doesn't work - which often happens - it's nice to remind yourself that perhaps after all you're not so good at this job and the schoolmaster may have been right."
(Reporting by Patrick Lannin, Alistair Scrutton, Ben Hirschler, Kate Kelland, Kiyoshi Takenaka, Chris Wickham and Peter Graff; writing by Peter Graff; editing by Philippa Fletcher)
