It is now common knowledge that brain has no blood stream and no sensors of pain, making it easy to open-brain surgeries but at the same time the blood-brain barrier (BBB) prevents delivery of crucial therapies to treat brain tumours.
However, in a first of its kind, Sunnybrook scientists made history when they used ultrasound to non-invasively breach the blood-brain barrier and deliver chemotherapy into the brain tumour of a patient. Essentially they poked holes in the “saran wrap” and allowed the chemicals to pass through and get delivered inside the brain.
“The blood-brain barrier has been a persistent obstacle to delivering valuable therapies to treat disease such as tumours,” said Dr. Todd Mainprize, Neurosurgeon in the Hurvitz Brain Sciences Program at Sunnybrook Health Sciences Centre.
The team was able to temporarily open the BBB barrier in a patient and delivered minute deposits of chemotherapy directly to the brain tumour. First they infused a chemotherapy drug, then tiny, microscopic bubbles, into the bloodstream of a patient with a malignant brain tumour.
Since the microbubbles are smaller than red blood cells, they could pass harmlessly through the circulation. Later, using an MRI-guided low-intensity ultrasound waves near the tumour were repeatedly compressed and expanded the microbubbles, causing them to vibrate and loosen tight junctions of the BBB area cells. Once the barrier was opened, the chemotherapy flowed through and deposited itself in the targeted region.
“This technique will open up new opportunities to deliver potentially much more effective treatments,” says Dr. Todd Mainprize, Assistant Professor in the Division of Neurosurgery at University of Toronto.
Dr. Kullervo Hynynen, Director of Physical Sciences at Sunnybrook Research Institute, worked with industry partner Insightec for about two decades developing the new technology, which is in a clinic-ready stage. To understand the mechyanism, in less than 24 hours after breaching the blood brain barrier, the tumour and some surrounding tissues were surgically removed for pathological examination.
The new breakthrough will help in treating brain-cancer patients with drug therapies to parts of the brain protected by the blood brain barrier, including researching treatments for patients with various kinds of brain tumours, Alzheimer’s disease, and some psychiatric conditions.
Apart from this case, 9 more participants will be given similar BBB therapy to test its feasibility and efficacy, said researchers. All those enrolled are actually scheduled for traditional neurosurgery to remove parts of their brain tumour.