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Monday, 30 April, 2001, 23:25 GMT 00:25 UK
Stem cells 'improve rat memory'
rat in jar
The older rats performed better after the transplants
Aged rats with poor memory improved after human stem cells were implanted in their brains, report scientists.

The finding reinforces the belief that the cells could one day help people with problems such as Parkinson's and Alzheimer's Disease.

The research, at the University of Illinois at Chicago, tested rats on their ability to remember the way out of a "water maze".

Older rats tended not to perform as well at the task compared to younger rats.

However, after the laboratory-grown stem cells were implanted in their brains, their performance improved radically - in one case, the older, memory-impaired rat was able to exit the maze faster than the younger counterpart.

Foetal tissue

Stem cells are the body's master cells, having the ability to "differentiate" into a wide variety of different cells used for different purposes in the body.

If the way the cells differentiate could be controlled, scientists believe they could prove a potent way of replacing certain types of cell - such as brain cells - previously thought irreplaceable.

However, the idea of inserting new cells to replace old ones received a setback recently when transplanted neural foetal tissue failed to help Parkinson's patients in many cases.

Flexible cells

However, the latest research, along with dozens of other projects, uses stem cells which have not yet differentiated into a particular cell type.

Lead researcher Kiminobu Sugaya said that this "malleable" quality meant that it could be easier for them to migrate to the part of the brain where they were needed most, and change into the necessary cell types.

Examination of the rat's brains after death showed that the cells had differentiated and grown dramatically in areas associated with spatial memory.

The transplanted stem cells may have helped both directly and indirectly

Kiminobu Sugaya
lead researcher
Sugaya said: "The transplanted stem cells may have helped both directly and indirectly. Previous studies have failed to produce working brain cells from transplants of stem cells."

However, there remains widespread concern about the safety of stem cells transplantation in humans, although early human trials have so far revealed no direct cause for concern.

Dr Jack Price, from the department of neuroscience at the Institute of Psychiatry in London, said advanced laboratory techniques were producing bunches of stem cells which appeared to adapt better when implanted in the brain.

He said: "We are trying to understand the process by which this happens better - at that point we will start to feel more comfortable about using the technology in humans."

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