John B Gurdon and Shinya Yamanaka share 2012 Nobel Prize for Medicine

The 2012 Nobel Prize in Physiology or Medicine was awarded jointly to John B Gurdon and Shinya Yamanaka "for the discovery that mature cells can be reprogrammed to become pluripotent"

''The Nobel Prize recognises two scientists who discovered that mature, specialised cells can be reprogrammed to become immature cells capable of developing into all tissues of the body. Their findings have revolutionised our understanding of how cells and organisms develop,'' the Nobel Prize committee said in its release.

Prof Gurdon's work in frogs demonstrated that adult cells could be introduced into an egg and that it could still form into a fully functional tadpole and frog. This fundamental biology discovery overturned years of previous theory and laid the foundation for current exciting research in induced pluripotent stem cells.

John B. Gurdon discovered in 1962 that the specialisation of cells is reversible. In a classic experiment, he replaced the immature cell nucleus in an egg cell of a frog with the nucleus from a mature intestinal cell. This modified egg cell developed into a normal tadpole. The DNA of the mature cell still had all the information needed to develop all cells in the frog.

Shinya Yamanaka discovered more than 40 years later, in 2006, how intact mature cells in mice could be reprogrammed to become immature stem cells. Surprisingly, by introducing only a few genes, he could reprogram mature cells to become pluripotent stem cells, i.e. immature cells that are able to develop into all types of cells in the body.

These groundbreaking discoveries have completely changed our view of the development and cellular specialisation. We now understand that the mature cell does not have to be confined forever to its specialised state. Textbooks have been rewritten and new research fields have been established. By reprogramming human cells, scientists have created new opportunities to study diseases and develop methods for diagnosis and therapy.