Could gene therapy provide a means of busting the plaques that cause Alzheimer鈥檚 disease?
Alzheimer鈥檚 occurs when a protein called amyloid-beta (A脽) accumulates in the regions of the brain concerned with memory and thought. Existing therapies treat the symptoms of the disease but do nothing to target this underlying cause.
Now, Matthew Hemming and his colleagues at Harvard Medical School in Boston have used gene therapy to boost levels of an enzyme called neprilysin in mice with the equivalent of Alzheimer鈥檚. Neprilysin was already known to degrade the amyloid protein and its levels are reduced in people with Alzheimer鈥檚.
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Hemming鈥檚 team took fibroblast cells from the skin of the mice and engineered them to contain the gene for neprilysin. When they injected these cells into the hippocampus, nearby plaques disappeared. Crucially, plaques further away also diminished. This is because the gene had been altered to create a form of neprilysin that can travel through the body instead of remaining bound to cell membranes. 鈥淚t allows the enzyme to go to the sites of A脽 accumulation rather than just sitting on the cell,鈥� says Hemming (PLoS Medicine, ).
The researchers now plan to inject the cells into other parts of the body, to see if neprilysin can still reach the brain. The ultimate goal is to incorporate the cells into a small implant that could be placed anywhere under the skin, says Hemming.
