Stem cells: Back to basics 24/08/07. By the Wellcome Trust A simple switch can reprogram mouse fibroblasts to form embryonic cells capable of making any tissue.

Embryonic stem cells are able to grow into all of the body's different cell types and could potentially have a wide range of therapeutic uses. But so far the only way of obtaining them has been by destroying embryos, a procedure fraught with ethical difficulties. Now scientists have found a remarkably simple way to wind back the clock inside fibroblasts and re-create this youthful 'pluripotent' state, bypassing the need for embryos or eggs in stem cell research.

Research teams led by Shinya Yamanaka (Kyoto University) and Rudolf Jaenisch (Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology) took mouse fibroblasts and used a virus to transfer four genes – Oct4, Sox-2, c-Myc and Klf-4 – into the cells. Using a selection technique that picked out cells that had activated Nanog, a gene unique to embryonic stem cells, they managed to isolate the tiny proportion of reprogrammed cells. These cells were indistinguishable from normal embryonic stem cells and, when injected into an early-stage mouse embryo, contributed to a wide range of different cell types. The research was an advance over a 2006 study by the Kyoto group that showed the technique was feasible (see Stem cells: Reprogramming pluripotency , 'Wellcome Science').

Such a surprisingly simple technique could be very powerful if it were to prove successful for human cells. For example, researchers could produce these pluripotent cells from people with particular diseases and use a 'disease in a dish' approach to study the changes in the cells as they develop or to test the effectiveness of drugs. In the long term, stem cells could be used to generate particular cell types to replace those damaged by disease.UK researchers have identified variants in three genes that predispose people to type 2 diabetes.

Image credit: Jorgos Nikas

References

Okita K et al. Generation of germline-competent induced pluripotent stem cells. Nature 2007;448(7151):313-7. Abstract

Wernig M et al. In vitro reprogramming of fibroblasts into a pluripotent ES-cell-like state. Nature 2007;448(7151):318-24. Abstract