War on Brain Tumors Now Includes Magnets and Sound

Michelle Bryner

Date: 09 August 2010 Time: 09:44 AM ET

The sophisticated biological systems that protect our brains and keep them running also make it difficult for doctors to treat brain tumors. But a new three-pronged attack developed by researchers could help doctors get past our bodies' defenses.

The method involves ultrasound beams to open up the blood-brain barrier (essentially gates that guard the contents of our brains against toxic materials), magnetized nanoparticles coated with an anti-cancer drug, and a magnetic field to guide those tiny particles to the tumor.

So far, the researchers have tested the method on rats that have a genetic propensity to develop brain tumors. They found they could deliver a drug concentration approximately 15 times higher than through traditional in-vivo methods, and that the rats survived 66 percent longer than untreated rats.

[Read "3-D Brain Model Could Revolutionize Neurology."]

Breaking with tradition

The typical way to treat brain tumors today involves a craniotomy, in which the cranium is cut open so that the tumor can be surgically removed, said study co-author Kuo-Chen Wei, chief of the brain tumor division at the Chang Gung Memorial Hospital in Taiwan.

Because the tumor cannot be completely removed, the surgeon must administer radiation and anti-cancer drugs to the tumor region following the craniotomy. The problem is that not enough of the anti-cancer drugs can be delivered to the tumor without damaging healthy brain tissue. (Anti-cancer drugs are extremely toxic to human tissue, which is why they work to kill off the cancerous tumors.)

As a result, the treatment is short-term, and the tumors typically come back, Wei told TechNewsDaily.

This new approach could possibly get enough drugs to the tumor to zap it for good, Wei said.

1-2-3 punch

Breaking into the brain without cutting open the skull, and then delivering toxic materials to a tumor wedged inside it, was no easy task.

The researchers injected tiny air bubbles into a vein leading to the rats' brains, then applied focused sound waves, which expanded the air bubbles, causing them to push against the brain barrier to create tiny openings for the nanoparticles to enter, Wei explained.

Once the particles were in the brain, a magnetic force was applied to guide them to the tumor. The researchers watched the process and its outcome using a magnetic resonance imaging (MRI) scanner.

For this method to be ready to treat brain tumors in humans, the researchers will need to fine-tune each of the technologies, Wei said. This shouldn’t take long, he said – maybe four or five years before clinical trials.

Wei and his colleagues detailed their findings online Monday in the Proceedings of the National Academy of Sciences.