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 Saturday, 28 December, 2002, 11:13 GMT
Stem cell debate rages on
Stem cell
Stem cells have so far failed to deliver miracle cures
One of the most controversial issues in medical science in 2002 was the development of stem cell technologies.

The debate looks set to continue in 2003, with researchers keen to start full clinical trials.

This new field of biological research promises to provide long-sought cures for diseases such as Parkinson's and Alzheimer's.

It could allow doctors to grow tissues, and possibly even whole organs, for transplants.

But practical therapies may be many years away - whatever the hype says.

Recent announcements suggest that more clinical trials should start in the New Year.

However, just as the pace of research seems to be speeding up, the problems that scientists need to overcome are also mounting.

Repairing damage

Stem cells could change the way diseases are treated. Scientists hope they will one day be used to replace cells which have died or stopped working, in diseases like Alzheimer's, multiple sclerosis and diabetes.

Until recently it was thought that the most versatile and useful types of stem cells came from embryos or foetuses, as these can develop into any kind of cell in the body. But their use presents a minefield of ethical dilemmas.

Human embryonic stem cells are taken from embryos that are just a few days old, destroying the embryo; while foetal stem cells are taken from aborted material.

In many countries, the debate about what type of research should be allowed and what should not rages on.

Ethical alternative

Ethical considerations are not the only obstacle facing researchers, however. Another problem is that embryonic stem cell treatments may not work.
Faults can accumulate as cells divide....

Professor Tom Kirkwood
Professor Tom Kirkwood from the University of Newcastle upon Tyne is one of Britain's leading researchers into ageing.

He believes the process of growing stem cells in the laboratory may limit their medical use.

"Setting aside the huge ethical questions that arise from using cells grown from a very early embryo, before we can use these cells in any kind of therapy we have to make them go through a large number of divisions in cell culture procedures," he said.

"And these are exactly the types of processes where faults can accumulate as cells divide and divide and divide - they have to copy and copy and copy their DNA - and we know that this is how some of the damage to DNA arises."

Pros and cons

Embryos and foetuses are not the only sources of stem cells, as they are also found in adults.

Adult stem cells were once considered not to be as versatile as the embryonic variety, as they cannot develop into any type of cell.

But over the last year, evidence has been accumulating that they may be much more useful than scientists previously believed.

Blood stem cells, we now know, can develop into muscles and nerves; muscle stem cells can develop into brain cells.

There are other advantages to using adult stem cells. If doctors use embryonic or foetal cells there is a danger that the patients' body may reject the new cells.

But if adult stem cells are used from the patients themselves, then there is little danger of them being rejected and any future treatments would be more likely to work.

Ageing effects

Again there are possible problems with adult stem cells. Professor Kirkwood said that they could turn out to be unusable in medical treatments.

"Stem cells that are taken from the adult body have been affected by the ageing process and may be damaged by that process and may not work as well," he said.

There has been a lot of hype over the past few years about the potential of stem cell therapies.

Companies have invested millions in the hope they will bring about a revolution in medicine.

It may yet prove to be a wise investment, but as scientists like Tom Kirkwood are proving, there is no guarantee.

See also:

20 Dec 02 | Science/Nature
11 Nov 02 | Science/Nature
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27 Feb 02 | Science/Nature
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