Magnetic resonance imaging (MRI) equipment has become a cornerstone technology of medical diagnosis. But Sylvain Martel, a professor of computer engineering at Polytechnique Montréal, is taking MRI research a step further by utilizing it as an equally valuable tool of active treatment.
Martel has spent much of the past decade reverse-engineering these complex devices so they can be used to guide nanoscale agents into the body’s many nooks and crannies. The latest milestone in this ongoing research effort has been a demonstration of how those agents could make their way past the impermeable zone that separates the brain from the bloodstream. This barrier effectively protects vital neural tissues from any kind of blood-borne infection but it also makes it nearly impossible to deliver drugs to these same tissues.
However, if those drugs are attached to iron oxide nanoparticles, they can be navigated close to the blood-brain barrier using an MRI-based control system. Then, once they are in position, a modulated magnetic field will exploit the Néel effect, putting the particles under mechanical stress and heating them up. This action opens up the barrier so they can pass through an opening that will close within hours without any side effects. “When you get very small, you have to keep it as simple as possible, so we gave the same components many functions,” says Martel, who points out that the nanoparticles provide propulsion, serve as a contrast agent for imaging and generate the access point to the brain.
Martel and his colleagues have successfully applied this technique in several different animal models and published their findings in the Journal of Controlled Release. Martel acknowledges that any kind of human trial will be a long way off but is pleased to continue demonstrating an ability to introduce new possibilities for MRI. “Right now we’re at the proof-of-concept stage,” he says.