Blood-brain barrier jiggled loose to deliver medicine

In its job protecting the brain from would-be invaders, the blood-brain barrier also blocks medicines from reaching the brain.  But on November 5, ultrasound zaps shook loose that tight barrier in a woman who has a brain tumor, potentially granting entry to a chemotherapy drug. The technique, which relies on tiny bubbles set jiggling by ultrasound beams, has shown promise in animal models (SN: 9/27/08, p. 20). This is the first time it has been tried on a person, says neurosurgeon Todd Mainprize of Sunnybrook Health Sciences Centre in Toronto, who led the procedure.

Mainprize and colleagues injected microbubbles, a chemotherapy drug and an imaging agent that could be visualized by a scanner into the blood of the woman. Then, targeted ultrasound beams passed through her brain, where they made the microbubbles in her blood vessels contract and expand. This jostling temporarily opened the blood-brain barrier, allowing the imaging agent — and presumably the drug — to enter the brain tissue near her tumor, Mainprize reported in a November 10 media briefing.

The unpublished results are preliminary; the researchers don’t how much of the drug made it into the tumor, or how the patient will fare long-term. Mainprize and colleagues plan to perform the procedure on other patients to test whether the procedure is safe and feasible. If so, the method might ultimately be used to deliver medicine to treat a wide range of brain maladies such as tumors and Alzheimer’s disease.