Six patients taking part in a gene therapy trial for Alzheimer's disease are showing an improvement in their condition, a US team reports. Scientists at the University of California, San Diego (UCSD) have shown that injecting genetically modified (GM) skin cells into the brain appears to slow the effects of the disorder. Their results, reported in the journal Nature Medicine, suggest that the treatment could slow the rate of cognitive decline by as much as 50 per cent.
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, according to 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, during 2001 and 2002. 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.
The team reported preliminary results from the trial at a conference last April. In two of the volunteers, the surgery was unsuccessful, and one of these patients died five weeks after the treatment. However, the other six participants showed a drop of up to 50 per cent in the expected rate of mental decline. Now, the scientists report that brain scans and cognitive tests confirm these findings, and also show increased brain activity. In addition, they examined brain tissue from the participant who had died, and found that some of the brain tissue that had been dying off was regrowing, close to the injection site.
Tuszynski said that if validated in further clinical trials, the approach would represent 'a substantially more effective therapy than current treatments for Alzheimer's disease'. However, US neurologist Rudolf Tanzi cautioned that the treatment was 'not a cure but a way of treating the symptoms of the disease'. He said that the main problem was regulating the amount of NGF in the brain, and that carrying out a larger trial will be 'tricky', adding 'I am not sure the level of benefit will outweigh the risk'. Clive Ballard, director of research at the Alzheimer's Society, said that 'the findings are consistent with previous studies in animals, and offer an extremely exciting possibility of a novel therapy'.
Sources and References
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Alzheimer's gene therapy hailed
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New treatment for Alzheimer's
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