Dr. Elisa Konofagou, professor of biomedical engineering and
radiology at Columbia University, has shown for the first time that the
size of molecules crossing the blood brain barrier (BBB) can be manipulated
through acoustic pressure produced by an ultrasound beam.
Delivering drugs to the brain is extremely difficult as most
small molecules and all large molecules cannot cross.
Konofagou combined microbubbles, bubbles with lipid or
protein shells that are filled with gas, and adjustments of acoustic pressure
to examine the delivery of various sized sugar molecules (Dextran) to the
hippocampus, a major part of the brain that
is involved in memory forming, organizing, and storing
By choosing a specific pressure, Konofagou was able to cause
the microbubbles to oscillate and form openings in the BBB with minimal
microscopic damage. She discovered that lower pressures allow smaller molecules
to go through the barrier while higher pressures allow larger molecules to go
through the barrier.
"This is a significant breakthrough in getting drugs
delivered to specific parts of the brain precisely, non-invasively, and safely,
and may help in the treatment of central nervous system diseases like
Parkinson's and Alzheimer's," said Konofagou.
Her experiment included setting the left hippocampus of the
mouse model to be the area of interest and the right side of the hippocampus to
be the control. Using fluorescence imaging, Konofagou was able to ensure the
greater uptake of the molecules in the left hippocampus of the mouse model in
comparison to the right hippocampus.
The study was published in the Journal of Cerebral Blood
Flow & Metabolism