In May 2017, scientists at Sunnybrook Health Sciences
Centre in Toronto, Canada made history as the first in the world to use focused
ultrasound to temporarily break through the blood-brain barrier (BBB) in
patients with Alzheimer’s disease.
The BBB is composed of high-density cells around the smallest
blood vessels in the brain, known as the capillaries. While preventing toxic
substances in the bloodstream from reaching the brain, this barrier, however,
also prevents drug therapies from entering the brain to treat diseases. As Dr.
Sandra Black – internationally renowned Brill Chair of Neurology at Sunnybrook Health
Sciences Centre and University of Toronto – says, “There are many therapeutic
drug treatments that do not work or cannot be properly tested in Alzheimer’s
disease because they cannot pass the BBB.”
In November 2015, Sunnybrook researchers successfully
opened the BBB for the first time, testing the ability to deliver chemotherapy
directly into a patient’s brain tumour. Using MRI-guided focused ultrasound, this
recent phase 1 trial in May 2017 was the first time the BBB was opened in
patients with Alzheimer’s, although no drug treatments were given. If this
trial is successful, researchers will consider conducting another trial to test
introducing small amounts of drug therapies through the BBB. They may even
target the part of the brain that is most affected by dementia – the
hippocampus, which is responsible for creating new memories.
The ability to open up the BBB opens up new
possibilities of treating brain disorders. “By opening up the BBB using low
frequency ultrasound, we’ve taken a small but important step that opens up a
whole new vista of possibilities. The hope is there may be a way to eventually
open up multiple little windows, in a gentle way, in order to get large
molecules like drugs and even stem cells into the brain,” says Dr. Sandra
Black.
More information about Sunnybrook’s research on
opening the BBB in dementia patients can be found here: https://sunnybrook.ca/media/item.asp?c=&i=1562&page=33939&f=alzheimers-focused-ultrasound-blood-brain-barrier
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