While a presidential veto looms for the embryonic stem cell legislation that passed the U.S. House of Representatives last week, three groups of academics published the transformation of fibroblasts into pluripotent embryonic stem cells in mice. General media reports suggested that the finding could eventually take the controversial use of human embryos out of the equation. However, the researchers expect that additional research on human embryonic cells will be necessary to translate the technique from murine to human cells.

The papers build on a 2006 publication by researchers at Kyoto University in which genes for four transcription factors - Oct4, Sox2, c-myc and Klf4 - were used to reprogram a mouse fibroblast into a cell that had many - but not all - properties of pluripotent embryonic stem cells. The researchers transferred the transcription factor genes, which were systematically whittled down to four from 24, into fibroblast cells using a retroviral vector.