A new study has cast doubt on whether research using animal-human embryos will ever lead to medical treatments.
A team of scientists in Massachusetts tried to produce stem cells from embryos created from animal and human material.
But when they put the nuclei of human cells into animal eggs they found that the mechanism needed to generate the stem cells didn’t work.
“Instead of turning on the right genes, it turns out the animal eggs actually turn them off,” said senior researcher Dr Robert Lanza.
The team said their results “call into question” the ability of animal-human embryos to generate stem cells for the medical treatment of human beings.
They do, however, claim that using a similar process to clone human embryos would be more likely to produce embryonic stem cells.
But Alan Trouson, of the California Institute for Regenerative Medicine, says this is also impractical, because human eggs are in such short supply.
During debates last year over new embryology laws, research using animal-human embryos was held up as crucial to the development of new medical treatments.
Despite divisions in the scientific community over the potential of such research, and significant ethical concerns, it was eventually allowed by the Human Fertilisation and Embryology Act 2008.
Since then there have been several advances in research using adult stem cells, which can be produced without the destruction of embryos.
Last year a woman’s windpipe was successfully repaired using tissue that had been custom-made from her own stem cells.
A number of scientists have turned away from embryonic stem cell research altogether, turning to the adult stem cell route because they believe it is more likely to yield treatments.
Yet it has been argued that the Government, keen to see the UK at the forefront of embryonic stem cell technology, is failing to fund adult stem cell alternatives properly.
This led one scientist, Professor Colin McGuckin, to leave the University of Newcastle and take his adult stem cell research abroad.
Professor Anthony Hollander, one of the scientists responsible for last year’s wind-pipe transplant, commented on Prof McGuckin’s decision: “We desperately need more funding for adult stem-cell research, because with these cells we really can make a difference to patients’ lives, and we can do it now, not in ten years’ time as is promised for embryonic stem cells.”