Stem cells could lessen need for lab mice

Researchers in the US have for the first time genetically modifed human embryonic stem cells, the root from which all tissue grows, potentially opening the door to a powerful tool for medical research.

Scientists at the University of Wisconsin laboratory that first created a continuously replicating line of human stem cells have worked out how to silence individual genes in the cells.

The method is similar to that of creating so-called "knockout mice", lab mice with particular genes inactive, that are used by the tens of thousands to "model" human diseases. "It allows us to manipulate every part of the human genome [complete gene set] we want," said Thomas Zwaka, who did the research, published today in the journal Nature Biotechnology.

The human knockout cells have three potential uses. One is to supplement knockout mice; in Britain, the government has moved to placate animal rights activists by funding more research to lessen use of laboratory animals.

Another use is to help scientists trying to make embryonic stem cells grow into cells for transplant - brain cells for Parkinson's sufferers, pancreatic cells for diabetics - by suppressing certain genes out of the full set within the cells.

A third use could be to avoid tissues for transplant having to be cloned from the patient's own cells to prevent rejection; the genes that cause rejection could simply be switched off.