Can four little genes (or maybe six) really make the whole bitter debate about human embryonic stem cells go away?

Two separate tems of scientists are announcing this morning that they can create the precious cells, which have the potential to turn into any of the 200-plus kinds of cells in the human body, without producing, let alone destroying, human embryos, which until now have been the only source of embryonic stem cells. If they're right, and if the recipe works reliably, then stem cells could be created from cells no more ethically problematic than human skin.

Every cell of the human body contains the exact same DNA (sperm, eggs and red blood cells being the only exceptions)—that is, the complete human genome. But neither skin cells nor muscle cells nor liver cells nor any other specialized cell follows the whole program. Only fertilized eggs—the union of egg and sperm—do that, using all the genes to produce a complete individual. Because the vast majority of genes in adult cells are silent, no one has been able to take, say, skin cells and make them turn into any chosen kind of cell, such as neurons to treat patients with Parkinson’s disease. Only the cells in very early embryos—stem cells—can transform into whatever cell you want, and you all know the ethical problems that research on stem cells raises in some quarters.

If only it were possible to take one of those specialized, or differentiated, cells and roll back the clock, back to when that skin or kidney or liver or other cell was a stem cell and had that unlimited potential. According to this morning announcement, it is possible, and scientists in the U.S. and Japan have done it.