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.