Gene therapy halts early Alzheimer's disease in mice

A new gene therapy has slowed the progress of early Alzheimer's disease in mice.

Researchers at Imperial College London used a modified virus to insert a gene called PGC-1 alpha into transgenic mice. The mice had been genetically altered to develop amyloid plaques in their brains, a key feature of the disease. However, mice receiving this treatment developed fewer plaques and performed normally on memory tests.

Dr Magdalena Sastre, senior author of the study, said: 'There are many hurdles to overcome, and at the moment the only way to deliver the gene is via an injection directly into the brain. However, this proof of concept study shows this approach warrants further investigation.'

Amyloid plaques are clumps of protein that develop in the brains of people with Alzheimer's disease, where they cause brain cells die. This leads to symptoms including loss of memory, confusion, and change in personality.

The researchers had previously shown that the PGC-1 alpha gene could prevent the formation of a key protein found in the plaques. The PGC-1 alpha protein is an enzyme involved in metabolism of sugar and fat in the body. It is found at decreased levels in brains affected by Alzheimer's disease.

They inserted the gene inside a harmless virus vector and injected it into the hippocampus and cortex, regions of the brain that are susceptible to Alzheimer's disease.

After four months, the mice that had received the gene therapy had very few plaques compared with mice that had not received the therapy. There was no loss of brain cells in the hippocampus, and they also performed as well as healthy mice in memory tasks. They also had a reduction in their number of glial cells, a type of brain cell which in Alzheimer's disease can release toxic inflammatory substances and cause further cell damage.

Currently there are no treatments that target the progression of the disease; the team believes this gene therapy would be most beneficial in its early stages.

'We are still years from using this in the clinic,' cautioned Dr Sastre. 'However, in a disease that urgently needs new options for patients, this work provides hope for future therapies.'

Rob Howard, professor of old age psychiatry at University College London, who was not involved in the study, called the research 'promising' but said it was important to remember that the mice used in the study do not have actual Alzheimer's disease. They have been modified to over-produce beta-amyloid protein in their brains, and people with the disease show additional clinical symptoms.

'This work should best be viewed as demonstrating proof of concept in blocking the development of one aspect of the brain pathology seen in Alzheimer's disease, within a genetically modified animal model,' said Professor Howard. 'This may or may not translate into benefits when applied to humans.'

The study was published in the PNAS journal.