Scientists have developed a brain implant that can turn the patient’s immune system against Alzheimer’s disease.
Alzheimer’s disease is a progressive disease that destroys memory and causes cognitive decline. One of the key signs of early Alzheimer’s is the loss of synapses, structures that connect neurons in the brain. Synapses allow information to flow between neurons. They are required for all brain functions, particularly for learning and forming memories. The loss of synapses occurs before the clinical symptoms of Alzheimer’s are apparent and long before the nerve cells die.
One of the two major hallmarks of Alzheimer’s is the presence of amyloid plaque deposits in the brain. Alzheimer’s causes certain proteins, produced normally by the body, to abnormally divide. This, in turn, causes the presence of amyloid plaques. These beta-amyloid (Abeta) plaques are toxic to neurons.
Ideally, one of the best ways to fight plaques would be to prevent them altogether by having the patient’s own immune system naturally attack and clear them. This method requires “tagging” the Abeta proteins with antibodies that would signal the body’s immune system to attack and clear Abeta. This method is most effective when the treatment is delivered as early as possible, before the first signs of cognitive decline.
A major flaw with this method has been that it requires repeated vaccine injections that can cause side effects. Now, researchers have solved the problem by developing a capsule implant that delivers a steady and safe flow of antibodies.
The capsule’s design was based on the a previous design developed by the lab of Patrick Aebischer at EPFL that was published in 2014. Aebischer worked on this study as well. The implant uses biocompatible materials and could be easily reproduced for large-scale manufacturing.
The researchers first worked on genetically engineering cells taken from muscle tissue to produce antibodies that would recognize and target Abeta. The researchers added these cells into the capsule, along with a hydrogel that facilitates cell growth.
An obstacle in producing the capsule was developing an implant that the body would accept. Similar to organ transplants, if the implant isn’t compatible with the patient, the patient’s immune system will reject it. The capsule membrane shields the cells from being identified and rejected. This allows a single patient’s cells to be used on multiple patients. The permeable membrane also allows the cells to interact with the surrounding tissues in order to get the necessary nutrients and molecules.
The scientists tested the implant using an Alzheimer’s disease mouse model. Over a period of 39 weeks, the capsule prevented the formation of Abeta. The mice displayed a dramatic reduction of Abeta plaque load.
The development proves that encapsulated cell implants can safely and effectively deliver antibodies to treat Alzheimer’s disease. The treatment could also be applied to other neurodegenerative disorders that feature defective proteins.
The research was published in March 2016 in the journal Brain
Sources: ECOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE press release via EurekAlert!
, study via Brain