Blood brain barrier

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World first: blood-brain barrier opened non-invasively to deliver chemotherapy




Sunday, November 08, 2015
Sunnybrook scientists made history this week as they used focused ultrasound to non-invasively breach the blood-brain barrier and more effectively deliver chemotherapy into the brain tumour of a patient.

Each person has a protective barrier that normally restricts the passage of substances from the bloodstream into the brain protecting it from toxic chemicals.

“The blood-brain barrier (BBB) has been a persistent obstacle to delivering valuable therapies to treat disease such as tumours,” says Dr. Todd Mainprize, principal investigator of the study and Neurosurgeon in the Hurvitz Brain Sciences Program at Sunnybrook Health Sciences Centre.

“We are encouraged that we were able to temporarily open this barrier in a patient to deliver chemotherapy directly to the brain tumour.”

The research team infused a chemotherapy drug, then tiny, microscopic bubbles, into the bloodstream of a patient with a malignant brain tumour. The microbubbles are smaller than red blood cells and pass harmlessly through the circulation. The researchers then used state-of-the-art MRI-guided focused low-intensity ultrasound (sound waves) to target blood vessels in the BBB area near the tumour. The waves repeatedly compress and expand the microbubbles, causing them to vibrate and loosen tight junctions of the cells comprising the BBB. Once the barrier was opened, the chemotherapy flowed through and deposited into the targeted regions.

“Some of the most exciting and novel therapeutics for the treatment of malignant brain tumours are not able to reach the tumour cells because of the blood brain barrier. This technique will open up new opportunities to deliver potentially much more effective treatments to the targeted areas,” says Dr. Todd Mainprize, also an 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 almost two decades to develop the technology and bring it to a clinic-ready state. “The success of this case is gratifying,” he says. “My hope now is that many patients will eventually benefit from it.”