Scientists from the Sunnybrook Health Sciences Centre in Canada have made history by, for the very first time, using focussed 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.
Principal investigator Dr Todd Mainprize said: “The blood-brain barrier has been a persistent obstacle to delivering valuable therapies to treat disease such as tumours. 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.
Dr Mainprize added: “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.”
Less than 24 hours after breaching the blood brain barrier, the tumour and some surrounding tissues were surgically removed and sent to pathology to measure differences in the concentration of chemotherapy that deposited in the area treated by the focused ultrasound and the area not treated.
Dr Neal Kassell, chairman of the Focused Ultrasound Foundation, commented: “Breaching this barrier opens up a new frontier in treating brain disorders. We are encouraged by the momentum building for the use of focused ultrasound to non-invasively deliver therapies for a number of brain disorders.”