A British stem-cell discovery has brought scientists within sight of the medical revolution which could lead to spare body tissue being mass-produced in laboratories.

The first clinical steps towards this goal could now be just five years away, according to one leading scientist.

Stem cells produced from early-stage embryos are "pluripotent", having the potential to develop into almost any kind of body tissue, from brain to bone. The ability to grow different types of cells which can be used to treat a host of diseases, including currently incurable conditions such as type 1 diabetes, Parkinson's and motor neurone disease, is the "Holy Grail" of stem-cell research.

Today, two teams of scientists publish details of research which brings them closer to realising that ambition. A new type of cell has been found in the embryos of mice and rats which is virtually indistinguishable from a human embryonic stem cell. The Oxford and Cambridge scientists believe it will provide an invaluable model that is certain to accelerate research into basic stem-cell biology.

With the cells readily available from mice, researchers will also no longer have to rely on surplus human embryos from in-vitro fertilisation clinics, which are in very short supply. Ethical objections to experimenting with human embryos will cease to be relevant.

Embryonic stem cells (ESCs) have always previously been grown in the laboratory from tissue taken from the blastocyst, a pinhead-sized embryo, very early in its development which has not yet implanted into the womb.

But scientists found the mouse "epiblast stem cells" had many of the properties of human ESCs. They not only grew like human cells but displayed similar gene activity and produced the same kind of surface proteins.

"The epiblast stem cells', as they have been named, constitute the missing link between mouse and human embryonic stem cells," said Professor Roger Pedersen, who led the Medical Research Council-funded Cambridge team, working with both mice and rats.

Professor Pedersen said he was confident the research would speed up progress towards clinical trials of embryonic stem-cell treatments. "I think we're talking five years," he said. "Those would be very early studies that involve a human individual. I think we can envisage larger-scale clinical trials occurring within a decade, certainly."

Both scien-tific papers appear today in the journal Nature. The fact two independent teams made the same discovery at the same time adds considerable weight to the findings.

Professor Sir Richard Gardner, who led the Oxford scientists, said: "Having both studies reach the same conclusions at the same time allows other researchers to use this new information immediately in their research.

"We are reaching a critical mass of understanding about these cells, which should enable us to make the most of them in coming years."

Earlier this month, a team of scientists from University College London unveiled plans to use a stem-cell treatment to overcome age-related blindness.

However, they acknowledged major hurdles would have to be crossed first. One of the biggest obstacles is preventing ESCs producing tumours once they are injected into human tissue.