Scientists in the United States have cloned an artificial embryo from monkey-skin cells in a process that could provide a near limitless supply of highly valuable stem cells.
Researchers hope that this first successful primate embryo clone achieved in a rhesus macaque monkey could be reproduced in humans, something that could provide embryonic stem cells without having to destroy fertilised human embryos.
More importantly, the method would produce patient-specific stem cells perfectly matched to the original donor.
There is a worldwide push to develop methods for producing embryonic stem cells because they can grow into any of the body's various cell types, from brain to bone to heart.
Although the therapies have yet to be proven, researchers believe stem cells could be used to repair the damage caused by heart attacks, reverse diseases such as Parkinson's and cure those with type 1 diabetes.
There are huge ethical concerns, however, because the best and most powerful stem cells become available through the destruction of days-old fertilised human embryos.
The work by US scientists led by Dr Shoukhrat Mitalipov, from Oregon Health and Science University in Beaverton, was released early by the journal Nature given the scientific and media excitement over the news.
They duplicated the cloning methods used in Scotland to produce the world's first large mammal clone, Dolly the sheep.
They removed the nucleus from a monkey-egg cell, replacing it with the nucleus from a skin cell. This was coaxed to grow into an early-stage embryo, known as a blastocyst, from which they recovered embryonic stem cells.
This has already been achieved in mice but this is the first success using cells from a primate.
The success rate was low - just 20 blastocysts from 304 egg cells taken from 14 rhesus macaque monkeys. But the 20 blastocysts delivered two stem cell lines that perpetuate to produce large numbers of stem cells.
Cells derived in this way from a human donor could be enormously valuable, not just because they are stem cells.
They would provide a perfect genetic match to the donor, something that should prevent the risk of cell rejection once transplanted into diseased tissues.
The scientist who led the group that cloned Dolly, Prof Ian Wilmut, yesterday welcomed the success of the US team.
"The ability to produce embryo stem cells from cloned human embryos would create entirely new opportunities to study inherited diseases," he said.