Scientists last night dismissed fears of a "Brave New World" of cloned superhumans, after reports that a lamb has been cloned from one cell taken from the udder of an adult sheep.
In this week's issue of the science journal Nature, Ian Wilmut of the Roslin Institute near Edinburgh will reveal details of how he took a cell from the mammary gland of an adult sheep, treated it to "forget" it was a specialised cell, and fused it into an unfertilised egg from which all DNA had been removed.
He and colleagues then implanted the test-tube embryo in a surrogate mother. The result was a clone.
"Apart from showing the biological principle that it is possible to get a cell to begin development again in this way – which has fascinating implications for studies of cancer and suchlike – the initial importance is that we will be able to use this for research in biology and also to make new health care products," said Dr Wilmut.
Dolly, the lamb born from the test-tube embryo, is an identical twin of the "parent" ewe that donated the cell.
The birth is a world first: biologists have been cloning plants from cells for decades, and from frogs for years. Last year Dr Wilmut and colleagues made history by cloning two lambs from a cell line preserved in a laboratory. But that was done from embryo cells. Embryo cells divide, and for a while each new cell is identical with its parent. But then cells are mysteriously "instructed" to become bone, or skin, or brain or blood or nerve cells, and remain forever different from the cells of conception. What Dr Wilmut showed was that cells contained a "clock" that could be reset.
He said: "It will enable us to study genetic diseases for which there is now no cure and track down the mechanisms involved. The next step is to use the cells in culture in the lab and target genetic changes into that culture."
If sheep can be cloned, so in theory can humans. But even identical twins – clones from the same cell – do not behave identically. Dr Wilmut yesterday dismissed the idea of human clones, and other scientists said attempting to clone humans would be unlikely and pointless – as well as being illegal in Britain.
"It's a pretty risky technique with lots of abnormalities," said embryologist Lewis Wolpert of University College, London, who is chairman of the Committee for the Public Understanding of Science. "As I remember the stuff from amphibians, the embryos are sterile. You can't breed from cloned sheep."
Tim Radford
