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Wednesday, 20 September, 2000, 00:28 GMT 01:28 UK
Stem cell advance fuels embryo debate
Stem cells BBC
Scientists have high hopes for stem cell research
A study in which cells from the adult brain were turned into muscle is likely to fuel the debate over research using human embryos.

Many believe so-called stem cells extracted from embryo clones hold the key to future treatments for devastating conditions such as stroke, Alzheimer's disease or multiple sclerosis.

Common sense dictates that it is not possible to decide which approach is more promising until both have been explored.

Charles Jennings, Editor, Nature Neuroscience
Stem cells are the "master cells" which could, in theory, be used to produce virtually any type of replacement tissue for a damaged body.

But the Italian research supports the view that adult stem cells are far more flexible than previously realised.

The study adds weight to the argument that the use of embryos to generate stem cells may not be necessary.

Number of cells

Many scientists are keen to extract embryonic stem cells in a cloning procedure similar to the one that produced Dolly the sheep.

They believe the use of cells harvested from embryos offers the greatest potential to treat degenerative diseases - more so than for stem cells taken from adults which they argue are less easy to handle and control.

The cloning aspect of the work is also necessary, they argue, in order to provide tissue that is a perfect match for a patient.

An influential UK Government-commissioned report recently backed this view by recommending that scientists should be allowed to pursue such research - to the dismay of "pro-life" campaigners.

These groups believe that all life is sacred, even an embryo a few days old composed of a small number of cells.

'Weak evidence'

Now a study from Angelo Vescovi and Giulio Cossu, from the Institute for Stem Cell Research in Milan, is likely to stoke up the debate.

They took some undeveloped brain stem cells, naturally occurring in tiny quantities in adult mice, and managed to "re-programme" them to start behaving like muscle cells.

They also managed to do the same using neuronal stem cells taken from an adult human volunteer.

Although similar "re-programming" has been successfully completed before, this is some of the clearest proof yet of the future potential of cells harvested from adults rather than from embryos.

But Charles Jennings, the editor of Nature Neuroscience, which published the research, said that the argument that adult stem cells could render the production of embryos unnecessary was "based on weak evidence".

Injected into muscle

He said: "Common sense dictates that it is not possible to decide which approach is more promising until both have been explored.

"Given that the field is still so young, it is far too early to make that call."

Embryo BBC
Scientists want to create embryos for research
The Italian team produced clones of neuronal stem cells, which are cells with the potential to become any number of different types of brain cell.

These were then placed in a culture of muscle cells, and some mouse neuronal stem cells were also injected into developing mouse muscles.

In both cases, there was clear evidence that the brain cells were able to divide and develop into muscle cells.

'No guarantee'

The scientists believe it was the proximity to the mature muscle cells which triggered the change in the neuronal stem cells.

Where the neuronal stem cells were clustered together, and not all exposed to contact with the muscle cells, they were far more resistant to change.

Professor Richard Gardner chaired an influential Royal Society working party on the future of stem cell research and treatments. He agrees some measure of embryo research is needed now, despite the potential future ability to harvest and transform adult stem cells.

There was no guarantee, he said, that adult stem cells would prove the answer, despite promising research findings. He told BBC News Online: "It's really a matter of not closing any doors.

"Researchers need access to embryos to find out what can be done."

Although there was "growing evidence" that adult stem cells might be useful, there were still doubts, he said, both over the longevity of any cells created, the ability to harvest them from older patients, and the number of different types of cell that could be created from them.

"The use of adult stem cells involves overcoming some great difficulties."

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