Radio-controlled nanobots open the blood-brain barrier just the right amount in murine studies.

Magnetic nanoparticles can open the blood-brain barrier and deliver molecules directly to the brain, state researchers from the University of Montreal, Polytechnique Montréal, and CHU Sainte-Justine. This barrier runs inside almost all vessels in the brain and protects it from elements circulating in the blood that may be toxic to the brain. The research is important as currently, 98% of therapeutic molecules are also unable to cross the blood-brain barrier.

The team state that they successfully opened the barrier temporarily at the desired location for approximately 2 hours by a small elevation of the temperature generated by the nanoparticles which were exposed to a radio-frequency field.  The study is published in the Journal of Controlled Release.

The current study showed that this technique is not associated with any inflammation of the brain. This new result could lead to a breakthrough in the way nanoparticles are used in the treatment and diagnosis of brain diseases.  The team adds that at the present time, surgery is the only way to treat patients with brain disorders. Moreover, while surgeons are able to operate to remove certain kinds of tumors, some disorders are located in the brain stem, amongst nerves, making surgery impossible.

Although the technology was developed using murine models and has not yet been tested in humans, the researchers are confident that future research will enable its use in people.  Building on earlier findings and drawing on the global effort of an interdisciplinary team of researchers, this technology proposes a modern version of the vision described almost 40 years ago in the movie Fantastic Voyage, where a miniature submarine navigated in the vascular network to reach a specific region of the brain state the team.

In previous studies, the researchers have managed to manipulate the movement of nanoparticles through the body using the magnetic forces generated by magnetic resonance imaging (MRI) machines.  To open the blood-brain barrier, the magnetic nanoparticles are sent to the surface of the blood-brain barrier at a desired location in the brain. Although it was not the technique used in the current study, the placement could be achieved by using the MRI technology.

Building on this the researchers generated a radio-frequency field. The nanoparticles reacted to the radio-frequency field by dissipating heat thereby creating mechanical stress on the barrier. This allows a temporary and localized opening of the barrier for diffusion of therapeutics into the brain.

The team explains that the technique is unique in many ways.  The result is quite significant since they have shown in previous experiments that the same nanoparticles can also be used to navigate therapeutic agents in the vascular network using a clinical MRI scanner.  Linking the navigation capability with these new results would allow therapeutics to be delivered directly to a specific site of the brain, potentially improving significantly the efficacy of the treatment while avoiding the systemic circulation of toxic agents that affect healthy tissues and organs the team adds.

While other techniques have been developed for delivering drugs to the blood-brain barrier, they either open it too wide, exposing the brain to great risks, or they are not precise enough, leading to scattering of the drugs and possible unwanted side effect, this is not the case in the current animal study.

Although there are many hurdles to overcome before the technology can be used to treat humans, the research team is optimistic and state that they’re on the way to achieving the goal of developing a local drug delivery mechanism that will be able to treat oncologic, psychiatric, neurological and neurodegenerative disorders, amongst others.

Source:  University of Montreal