Scientists from UK and Japan have discovered a major new player in maintaining the immortality of embryonic stem (ES) cells. This breakthrough might one day allow scientists to turn any cell into an immortal, pluripotent cell that can be used for therapeutic purposes.

Shinya Yamanaka and his colleagues, from the Nara Institute of Science and Technology, and Austin Smith's group, at the Institute for Stem Cell Research in Edinburgh, independently identified a gene that was expressed specifically in pluripotent, undifferentiated cells. They named the gene Nanog — after the mythological Celtic land of the ever-young, Tir nan Og.

In two papers in Cell, the scientists showed that overexpression of Nanog prevented ES cells from differentiating. What is exciting is that Nanog seems to be a key factor in the transcription-factor network that is known to be required for the ES cell phenotype.

“As we know more and more about pluripotency, it probably will be possible to reprogram cells to make stem cells out of any cell in the body,” said James Thomson, the University of Wisconsin scientist who first isolated human embryonic stem cells in 1998 (Washington Post, 30th May 2003).

Although most of their experiments involved using the mouse version of Nanog in mouse cells, some involved the human version, which was identified thanks to its structural similarity to mouse Nanog. “If Nanog has the same effect in humans as we have found in mice, this will be a key step in the developing embryonic stem cells for medical treatments,” said Austin Smith (New Scientist, 30th May 2003).