Ultrasound therapy helps Alzheimer's mice through maze
June 27, 2017
Signs of the therapeutic potential of ultrasound continue to increase as new, early stage research - so far with mice only - demonstrates its capabilities against the challenges of Alzheimer’s disease.
Safely penetrating the brain’s protective layer – the blood barrier – without damaging essential tissue has been a vexatious problem for scientists working on brain disorders. For the last decade, Toronto biophysicist Kullervo Hynynen has been exploring the use of ultrasound to open portals in the blood-brain barrier, to better deliver therapies to combat the memory loss associated with this prevalent form of dementia. Hynynen and colleagues have been experimenting with low-wave ultrasound combined with an injection of microscopic blood-borne bubbles to create leaks in the blood-brain barrier. One use for this technique could be to deliver antibodies through these minute breaches to boost the microglia cells in the brain. Microglia cells help the brain to dispose of unwanted proteins. Toxic build-up of proteins into amyloid plaques is a characteristic feature of Alzheimer’s disease.
A new study, reported across the media last week, builds on this work and suggests that ultrasound on its own can contribute to memory improvement in mice. A team at the Queensland Brain Institute, Australia led by neuroscientist Jürgen Götz began injecting mice, genetically engineered to have amyloid plaques, with a solution of microbubbles. The mice were then split into two groups, one of which went on to receive a series of weekly scans across the skull with an ultrasound beam, after which all the mice were retested. The mice receiving the scans showed a 50% reduction of plaques. Furthermore, those mice also showed “full restoration of memory” across the three memory tasks on which they were tested, including the ability to find their way through a maze. The treated mice appeared to be unharmed, with no obvious tissue damage.
Whilst exciting, the findings are being treated with caution, not least because human brains are a good deal more complex than those of mice. Furthermore, the mice in the study were genetically modified only to have the amyloid plaques present in Alzheimer’s; the two other clinical features – cell damage and loss of neural connections were not addressed. However, other work by Hynynen and colleagues also suggests that ultrasound therapy may well have a positive effect on the birth and growth of new neurons, and thus on memory improvement.
In the next phase of their study, Gotz and his team will test the approach on larger mammals such as sheep. Meanwhile, the combined ultrasound – microbubble approach will shortly be used in one of its first clinical trialsto augment the benefit of chemotherapy in treating brain cancer. It is hoped the trial will also provide more safety data.