Sir John B Gurdon, Gurdon Institute, Cambridge, United Kingdom and Shinya Yamanaka, Kyoto University have been earlier today declared the joint winners of this year’s Nobel prize for medicine. They were the pioneers in reprogramming mature cells back into pluoripotent stem cells. Such cells are termed induced pluoripotent cells.
John Gurdon was the first person to clone frogs by transferring nucleus from a somatic cell into an anucleate zygote. This proved that the differentiated cells have the ability to revert back and give rise to other tissues. Incidentally, he published his famous experiment in 1962, the year Shinya Yamanaka was born.
Stem cells are undifferentiated cell lines which differentiate to yield mature cell lines or more stem cells. They are of two types, embryonic and adult. Embryonic stem cells come from embryos while the adult ones can be extracted from bone marrow, adipose tissue or blood.
Embryonic stem cells have not yet been approved for any treatments, though adult cells have been used for years to treat leukemia by bone marrow transplantation. Use of embryonic stem cells also raises obvious ethical concerns. These concerns were bypassed by Yamanaka’s work.
Shinya Yamanaka came up with a solution in induced pluripotent stem cells. iPS cells are derived from mature cells by transferring into them certain genes characteristic of stem cells. Viral vectors, usually retroviruses are used for transfection.
His group achieved the reprogramming in mouse fibroblasts in 2006, followed by human fibroblasts a year later. The breakthrough has raised hopes for regenerative medicine. iPS cells have many limitations yet but promises are in plenty as well.
Picture credits: The Nobel Prize in Physiology or Medicine 2012, Nobelprize.org. 8 Oct 2012