University of Maryland (UMD) researchers working with Bethesda-based Weinberg Medical Physics LLC
have developed a new technique to magnetically deliver drug-carrying
particles to cancer tumors or other hard-to-reach targets deep in the
body. The method has the potential to transform the way deep-tissue
tumors and diseases are treated.
UMD Professor Benjamin Shapiro, Fischell Department of Bioengineering (BioE) and the Institute for Systems Research,
and UMD alum Aleksandar Nacev (Aerospace B.S. ’09, BioE Ph.D. ’13)
teamed up with Weinberg Medical Physics to exploit fast pulsed magnetic
fields to focus nano-therapeutic magnetic particles to deep targets.
Their advances in this area were recently published in the journal Nano Letters.
For years, researchers have worked with magnetic nano-particles
loaded with therapies – such as drugs or genes – to develop noninvasive
techniques to direct therapies and diagnostics to targets in the body.
Magnetic nanoparticle research garnered media attention in October, when
Google X (Google’s innovation lab dedicated to furthering major
technological advancements) announced its interest in the use of
magnetic nano-particles for diagnostic applications.
Instead of surgery or systemically administered treatments, such as
chemotherapy, the use of magnetic particles as drug carriers could
potentially allow clinicians to use external electromagnets to focus
therapy to the precise locations of a disease within a patient. However,
until now, particles could only be attracted to a magnet, and thus
could not be concentrated to points away from the magnet face. As a
result, in prior clinical trials magnets held outside the body had only
been able to concentrate treatment to targets at or just below the skin
surface.
"What we have shown experimentally is that by exploiting the physics
of nanorods we can use fast pulsed magnetic fields to focus the
particles to a deep target between the magnets," Shapiro said.
These pulsed magnetic fields allowed the team to reverse the usual
behavior of magnetic nano-particles. Instead of a magnet attracting the
particles, they showed that an initial magnetic pulse can orient the
rod-shaped particles without pulling them, and then a subsequent pulse
can push the particles before the particles can reorient. By repeating
the pulses in sequence, the particles were focused to locations deep
between the electromagnets.
"The Holy Grail of magnetic drug targeting is the dream of using
magnets outside the body to minimally-invasively direct drug therapy to
anywhere inside the body, for example, to inoperable deep tumors or to
sections of the brain that have been damaged by trauma, vascular or
degenerative diseases,” said Dr. Irving Weinberg, a practicing physician
and president of Weinberg Medical Physics. “We have shown that fast
pulsing of external electromagnetic fields may be able to achieve this
goal."
Their study in Nano Letters, “Dynamic Inversion Enables External Magnets to Concentrate Ferromagnetic Rods to a Central Target,”
shows that, with appropriate external magnetic pulses, ferromagnetic
particles carrying drugs or molecules could be concentrated to arbitrary
deep locations between magnets. Nacev, Weinberg, Shapiro and their
fellow researchers are now working to demonstrate the therapeutic
potential of this method in a project funded by the National Cancer Institute (NCI) Small Business Innovation Research
program and featured at the NCI-sponsored Investor Conference in San
Francisco. Additionally, the research team recently launched IronFocus Medical, Inc., a startup company established to commercialize their invention. A video showing the magnetic focusing can be seen at http://ter.ps/magnetic.
"This technology could enable a new therapeutic modality that
combines the spatial precision of traditional image-guided radiation
with the biochemical specificity of molecular medicine," said Dr. John R. Adler, Vice President and Chief of New Clinical Applications for Varian Medical Systems.
Support for the Research
In addition to Nacev, Weinberg,
and Shapiro, research team members and co-authors include: Pavel Y.
Stepanov, Lamar Mair, Mario Urdaneta, and Mika Shimoji of Weinberg
Medical Physics LLC; and Dr. Stanley Fricke of Children’s National
Medical Center. Sam Kupfer, a summer student intern at Weinberg Medical
Physics, built the electromagnetic apparatus used in the experiment. The
fast magnetic fields were developed with funding from Small Business
Innovation Research grants awarded by the National Cancer Institute,
National Heart, Lung and Blood Institute, and the National Institute for
Neurological Disorders and Stroke. Funding to develop the correct
sequence of magnetic pulses was provided by the National Science
Foundation.