Stem cells 'may reverse Alzheimer's symptoms'

In a breakthrough bringing hope to millions, the cells repaired damaged parts of the brain and restored lost memory.

It is the first time that stem cells have been shown to reverse the type of memory problems associated with strokes, Alzheimer's and degenerative brain diseases.

Although the experiments were carried out on animals, the scientists say the technique could work on people.

British Alzheimer's campaigners called the experiments a "major advance".

More than 500,000 people suffer from Alzheimer's in Britain.

Although some drugs can slow its onset, there is no cure. Many doctors believe the best hope lies in stem cells - the body's potent "master cells" which can turn into different types of tissue.

In the study, published in the Journal of Neuroscience, researchers damaged the brains of mice and put them and some healthy animals through memory tests.

The animals were placed in boxes containing two objects. After the mice had grown accustomed to their surroundings, they were taken out and one of the objects was moved.

After they returned to the box, the healthy mice spent much more time sniffing around the object which had been moved.

The brain-damaged mice spent equal time investigating both - showing that they had not registered that one object had moved. When researchers injected nerve stem cells from newborn mice into the brains of the damaged mice, their memories improved.

They also had higher levels of synapsin, a chemical which stimulates connections between brain cells.

Dr Mathew Blurton-Jones, a member of the team at the University of California in Irvine, said that in past studies, stem cells injected into the brains of animals had survived and become part of the brain circuitry,

He told New Scientist: "We've now gone one stage further in showing that, once integrated, these new neurons are able to reverse cognitive deficits associated with neurodegeneration or neuronal loss.

"This study shows stem cells might benefit memory in stroke or traumatic brain injury - and potentially Alzheimer's disease. This has a huge potential but we have to be cautious not to rush into the clinic too early."

He stressed that much more animal work was needed before they can move on to humans.

The next step is to test stem cells in mice with an Alzheimer's-like disease.

Clive Ballard, director of research at the Alzheimer's Society, said: "This study is a major advance which demonstrates the potential of stem cell therapies. However, the race is on to develop treatments as effective in practice as in the laboratory.

"This study relies on a very specific approach using cells grown with animal growth factors. These cells are not suitable for human treatment and major obstacles still exist in applying this to people. But we anticipate a solution over the next few years."

Dr Paul Sanberg, director of the Centre of Excellence for Ageing and Brain Repair at the University of South Florida College of Medicine, said: "There is clearly a therapeutic potential to this. But it has to work with older brains."