We celebrate the 2012 Nobel Prize for Medicine awarded to Sir John Gurdon and Shinya Yamanaka for their groundbreaking contributions to the field of cell reprogramming. In 1962, in a series of experiments inspired by Briggs and King (1), Gurdon demonstrated that the nucleus of a frog somatic cell could be reprogrammed to behave like the nucleus of a fertilized frog egg (2). By inserting the nuclei of intestinal epithelial cells into enucleated eggs, Gurdon was able to create healthy swimming tadpoles. These experiments were the first successful instances of somatic cell nuclear transfer (SCNT) using genetically normal cells. In 2006, Yamanaka made a further conceptual leap. With four defined transcription factors he induced intact mouse somatic cells to revert to a pluripotent state without an egg or embryo as intermediary (3). These cells, dubbed induced pluripotent stem (iPS) cells, have the capacity to turn into all of the cells of the adult mouse. This result, now replicated with human cells, has enormous implications for basic research, clinical medicine, and reproduction. In the 44-year-long gap between Gurdon and Yamanaka's respective discoveries, recombinant DNA technology emerged, SCNT was successfully performed in mammals, and embryonic stem (ES) cell research took flight.
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