Scientists at the University of California in Irvine have for the first time used stem cells to reverse memory problems associated with strokes, Alzheimer's, and degenerative brain disease in mice. The researchers say that the cells repaired damaged parts of the brain and restored lost memory. They believe that their technique may also work on humans.

The researchers damaged the brains of mice and put them and some healthy animals through memory tests during the study, published in the Journal of Neuroscience. All the subjects were placed in boxes containing two objects. After the mice had become accustomed to their surroundings, they were taken out and one of the objects was moved.

When the mice were placed in the boxes again, the healthy mice spent much more time sniffing around the object that had been moved. The mice with their brains damaged spent equal time investigating both objects, indicating that they had not registered that one object had moved.

Upon being injected with nerve stem cells from newborn mice, the memories of the brain-damaged mice showed improvement. It also increased the mice’s levels of synapsin, a chemical which stimulates connections between brain cells. Dr Mathew Blurton-Jones, a member of the research team, said that in previous studies, stem cells injected into the brains of animals had survived and become part of the brain circuitry.

"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 Daily Mail quoted him as telling New Scientist magazine. "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 added.