Stem cells repair damaged memory in mice

Scientists from the University of California have announced findings that stem cell injections could restore memory lost through strokes or neurodegenerative diseases.

Publishing in the Journal of Neuroscience, the team hopes that in the future stem cells may be able to restore the memory of people suffering from Alzheimer's disease, or who have had their brains damaged by strokes.

Professor Frank LaFerla, of the University of California, said 'our research provides clear evidence that stem cells reverse memory loss'.

Mice genetically engineered with damaged cells in the hippocampus area of the brain were found to perform badly in a series of memory tests when compared with healthy mice. The mice were placed in boxes that contained two objects - when they had become used to this box they were removed, before one of the objects was moved to a different position. When they were returned to the boxes, the healthy mice spent more time sniffing the moved object, while the brain-damaged mice spent equal time sniffing both objects. This implied that the brain damaged mice had not registered that one of the objects had moved.

The team of scientists then injected stem cells from baby mice into the hippocampuses of the brain-damaged mice. Around three months later these mice began to show an improvement in their memories, with correspondingly improved scores on the memory tests. The mice that received the stem cells remembered their surroundings about 70 per cent of the time, which was the same as the healthy mice. The treated mice also showed elevated levels of synapsin, an enzyme that promotes connections between brain cells. Mathew Blutron-Jones, a member of the scientific team at the University of California, said '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'.

The team will conduct more work in animals, testing the stem cells on mice with an Alzheimer's-like disease, before moving to testing the procedure on humans. Michael Hunt from ReNeuron, a company hoping to win approval to use human neural stem cells on ten stroke patients before the end of 2007, welcomed the results stating 'this paper is encouraging, and certainly supportive, of endeavours in this field, including ours'.

Clive Ballard, director of research at the Alzheimer's Society welcomed the findings as a major advance, but warned that 'this study relies on a very specific approach using cells grown with animal 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'.