The locked door to transforming one type of cell into another may have opened a crack. In a development which could have manifold ethical, political and scientific implications, Austin Smith of the University of Edinburgh says in Nature that he has identified a gene which directs cell development. The discovery could eventually make it unnecessary to destroy embryos for their stem cells. "Until a couple of years ago I thought the idea of reprogramming was ridiculous because we had no scientific idea of how to achieve," says Smith. But after experiments with mouse embryos, he has changed his mind. It looks really encouraging. We could find a way to do this," he says.

The key gene in the process of cell transformation is called nanog. This appears to be the most important amongst a handful of reprogramming genes, although other proteins are also essential. If these new developments are verified, they could lead to the Holy Grail of regenerative medicine. Doctors might be able to take a simple biopsy of a patient's tissue, reprogram them into embryonic stem cells with one set of chemicals, and then direct these into new blood, pancreas, liver or other tissue. In the meantime, however, most scientists still insist that embryonic stem cells are needed for their research.