In Alzheimer's mouse models, the implantable capsule significantly reduced levels of beta-amyloid protein and plaques in mice.
Image credit: Patrick Aebischer (EPFL)
In the journal Brain, researchers from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland reveal how, when implanted under the skin, the capsule releases antibodies that travel to the brain and trigger the patient's immune system to clear beta-amyloid protein.
Beta-amyloid protein is believed to be a key player in the development of Alzheimer's disease. The protein clumps together in the brain, forming plaques that accumulate in the spaces between nerve cells, which researchers suggest interfere with the processes these cells need to survive.
Scientists have been searching for ways to tackle these plaques, and one idea has been to "tag" beta-amyloid proteins with antibodies that call on the immune system to attack and destroy them, before they can form plaques.
However, the researchers of this latest study - including Patrick Aebischer of the Brain Mind Institute at EPFL - note that such a treatment has to be administered in the early stages of cognitive decline to be most effective. This requires repeat injections, which can lead to adverse side effects.
But Aebischer and colleagues say their implantable capsule could offer a safer and highly effective alternative.
How does the implantable capsule work?
The capsule, described as a "macroencapsulation device," is 27 mm in length, 12 mm wide and 1.2 mm thick.
It consists of cells taken from muscle tissue that have been genetically engineered to produce high levels of antibodies that have the ability to recognize and target beta-amyloid proteins in the brain.
When implanted in tissue under the skin, the capsule gradually releases the antibodies into the bloodstream. From here, they cross from the blood to the brain to seek out and tag beta-amyloid protein, which triggers an immune system attack.
The following video from EPFL further explains how the implantable capsule works:
The team notes that not only must these genetically engineered cells release antibodies, but in order to avoid rejection from the immune system, they must be compatible with the patient.
As such, the cells are surrounded by two permeable membranes - fixed together by polypropylene frame - that not only protect them against immune system attack, but enable cells from a single donor to be used on multiple patients.
Furthermore, the permeable membranes allow the cells to soak up all the nutrients and molecules they need from surrounding tissue.
Alzheimer's mice showed reduction in beta-amyloid plaques
For their study, Aebischer and colleagues tested the capsule on mouse models of early Alzheimer's disease and assessed them for around 39 weeks.
On looking at the brains of the mice, the researchers found they showed a significant reduction in levels of beta-amyloid protein and plaques, suggesting that the continuous flow of antibodies produced by the capsule over the 39-week period prevented the plaques from forming.
Additionally, the team found that the mice demonstrated lower phosphorylation of a protein called tau, which is also believed to play a role in Alzheimer's development by forming "tangles" that build up inside nerve cells.
The authors believe that their findings provide proof-of-concept that an implantable, antibody-releasing capsule is an effective preventive option for Alzheimer's and other neurodegenerative diseases in which protein build-up plays a role, such as Parkinson's disease.
Medical News Today recently reported on a study in which researchers suggest it may one day be possible to retrieve 'lost' memories in patients with early Alzheimer's.