London:
Injecting a specific gene directly into the brain may offer a potential new therapy for halting the progress of Alzheimer's disease, especially when treatedat an early stage, a new study has claimed.
Scientists from Imperial College London in the UK used a type of modified virus to deliver a gene to brain cells in mice. Previous studies by the same team suggest this gene, called PGC1 alpha, may prevent the formation of a protein called amyloid-beta peptide in cells in the lab.
Amyloid-beta peptide is the main component of amyloid plaques, the sticky clumps of protein found in the brains of people with Alzheimer's disease. These plaques are thought to trigger the death of brain cells. Worldwide 47.5 million people are affected by dementia of which Alzheimer's is the most common form, researcher said.
There is no cure, although current drugs can help treat the symptoms of the disease. Magdalena Sastre, senior author of the research, hopes the new findings may one day provide a method of preventing the disease, or halting it in the early stages. "Although these findings are very early they suggest this gene therapy may have potential therapeutic use for patients," said Sastre.
"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," she said. The modified virus used in the experiments was called a lentivirus vector, and is commonly used in gene therapy, said Professor Nicholas Mazarakis, co-author of the study.
In the new study, the team injected the virus, containing the gene PGC-1 - alpha, into two areas of the brain in mice susceptible to Alzheimer's disease. The animals were treated at early stages of Alzheimer's, when they still had not developed amyloid plaques. After four months, the team found that mice who received the gene had very few amyloid plaques, compared with the untreated mice, who had multiple plaques in their brain.
The treated mice also performed as well in memory tasks as healthy mice. The tasks included challenges such as replacing a familiar object in the mouse's cage with a new one. If the mice had a healthy memory, they would explore the new object for longer. The team also discovered there was no loss of brain cells in the hippocampus of the mice who received the gene treatment.
The treated mice had a reduction in the number of glial cells, which in Alzheimer's disease can release toxic inflammatory substances that cause further cell damage. The team suggests injections of the gene would be most beneficial in the early stages of the disease, when the first symptoms appear. The finding was published in the journal Proceedings of the National Academy of Sciences.
