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New implantable capsule to fight Alzheimer’s

Friday, Mar 18, 2016,17:01 IST By Metrovaartha A A A

Geneva | Scientists have developed a tiny implantable capsule that can turn the patient’s immune system against the Alzheimer’s disease, by delivering a steady and safe flow of antibodies to the brain. One of the hypothesised causes of Alzheimer’s is the over-accumulation of the protein amyloid beta (Abeta) in different areas of the brain.

This results in the deposition of aggregated protein plaques, which are toxic to neurons. One of the most promising ways to fight the plaques is to tag the Abeta proteins with antibodies that signal the patient’s own immune system to attack and clear them.

To be most effective, this treatment has to be given as early as possible, before the first signs of cognitive decline. But this requires repeated vaccine injections, which can cause side effects. Scientists at Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland have now solved the problem with an implant that can deliver a steady and safe flow of antibodies to the patient’s brain to clear Abeta proteins. The capsule contains cells that have been genetically engineered to produce antibodies against Abeta.

It is implanted in the tissue under the skin, and over time the cells produce and release a steady flow of antibodies into the bloodstream, from where they cross over into the brain to target the Abeta plaques. It is made of two permeable membranes sealed together with a polypropylene frame.

The completed device is 27mm long, 12mm wide and 1.2mm thick, and contains a hydrogel that facilitates cell growth. The cells inside the capsule are important. Not only must they be able to produce antibodies, but they also have to be compatible with the patient, so as to not trigger the immune system against them, like a transplant can. This is where the capsule’s membranes come into play, shielding the cells from being identified and attacked by the immune system.

This protection also means that cells from a single donor can be used on multiple patients. Before going into capsule, the cells are first genetically engineered to produce antibodies that specifically recognise and target Abeta. The cells of choice are taken from muscle tissue, and the permeable membranes let them interact with the surrounding tissue to get all the nutrients and molecules they need. The researchers tested the device on mice with great success.

The mice – a genetic line that is commonly used to simulate Alzheimer’s disease – showed dramatic reduction of Abeta plaque load. Indeed, the constant flow of antibodies produced by the capsule over a course of 39 weeks prevented the formation of Abeta plaques in the brain. The treatment also reduced the phosphorylation of the protein tau, another sign of Alzheimer’s observed in these mice.