Scientists create nanoparticles that home in on brain tumor, increasing accuracy of surgical removal
In a study published online April 15 in Nature Medicine, a team led by
Sam Gambhir, MD,
PhD, professor and chair of radiology, showed that the minuscule nanoparticles
engineered in his lab homed in on and highlighted brain tumors, precisely
delineating their boundaries and greatly easing their complete removal.
The nanoparticles used in the study are essentially tiny gold balls coated
with imaging reagents. Each nanoparticle measures less than five one-millionths
of an inch in diameter — about one-sixtieth that of a human red blood cell. “We hypothesized that these particles, injected intravenously, would
preferentially home in on tumors but not healthy brain tissue,” said Gambhir. “The tiny blood vessels that feed a brain tumor are leaky,
so we hoped that the spheres would bleed out of these vessels and lodge in
nearby tumor material.” The particles’ gold cores, enhanced as they are by
specialized coatings, would then render the particles simultaneously visible to
three distinct methods of imaging (MRI, Photoacoustic and Raman imaging,), each contributing uniquely to an improved
surgical outcome.
Neither MRI nor photoacoustic imaging by themselves can distinguish healthy
from cancerous tissue at a sufficiently minute level to identify every last bit
of a tumor. Here Raman imaging, proved crucial. In the study, Raman signals emanated only from
tumor-ensconced nanoparticles, never from nanoparticle-free healthy tissue. So,
after the bulk of an animal’s tumor had been cleared, the highly sensitive
Raman-imaging technique was extremely accurate in flagging residual
micrometastases and tiny fingerlike tumor projections still holed up in adjacent
normal tissue that had been missed on visual inspection. This, in turn, enabled
these dangerous remnants’ removal...
The new technique could someday help improve the prognosis of patients with deadly brain cancers.
