Gene therapy hope for Alzheimer's

Injecting genetically modified (GM) skin cells into the brain appears to slow the effects of Alzheimer's disease, and could lead to a new treatment for this disorder, US researchers say. Scientists at the University of California, San Diego (UCSD) presented the results of a small, preliminary study at the American Academy of Neurology meeting, held in San Francisco last week. The results of the trial, initially designed to test the safety of the new gene therapy technique, suggest that it could halve the rate of mental decline in Alzheimer's disease patients.

Alzheimer's disease is caused by the gradual death of certain brain cells, especially in the areas involved in memory. Current drug treatments can help slow the progression of the disease, but only by around five per cent at best, says the UCSD team leader Mark Tuszynski. To test their new gene therapy treatment, he and his colleagues removed samples of skin from eight people in the early stages of Alzheimer's disease. They grew the skin cells in the laboratory, and genetically altered them so that they produced a protein called nerve growth factor (NGF), which prevents cell death in the brain. The team then injected millions of these 'GM' skin cells into ten different sites in the brain areas affected by the disease.

In two of the volunteers, the surgery was unsuccessful, but the other six participants showed a 50 per cent drop in the expected rate of mental decline. And one method of measuring mental ability showed a 65 per cent reduction in the rate of decline, in participants followed for more than 18 months after the operation. Tuszynski calls the results 'intriguing', adding that 'if these effects are borne out in larger, controlled trials, this could be a significant advance over existing therapies for Alzheimer's disease'.

The team plan to carry out a larger trial later this year - but this time, they will inject a modified virus directly into the brain to trigger NGF production, rather than using skin cells. The second trial will include 30-40 patients, and will have a control group who only receive surgery, and not the gene therapy. The results should be available in about a year and a half, says Tuszynski, and if everything goes well, the new treatment could be available in four years.