On July 22, 2010, at the 52nd annual meeting of the American Association of Physicists in Medicine (AAPM) in Philadelphia, PA, USA, investigators from Wake Forest University Baptist Medical Center (Winston-Salem, NC, USA) presented their findings on the latest development for this technology: iron-containing, multiwalled carbon nanotubes (MWCNTs), which are 10,000 times thinner than a human hair. In laboratory experiments, the team revealed that by using a magnetic resonance imaging (MRI) scanner, they could image these particles in living tissue, see as they approached a tumor, and target them with a laser, thereby destroying the tumor.

The research builds on an experimental technique for treating cancer called laser-induced thermal therapy (LITT), which uses energy from lasers to heat and destroy tumors. LITT works by virtue of the fact that certain nanoparticles such as MWCNTs can absorb the energy of a laser and then convert it into heat. If the nanoparticles are zapped while within a tumor, they will heat and kill the cancerous cells.

The problem with LITT, however, is that while a tumor may be distinctly visible in a medical scan, the particles are not. They cannot be tracked once injected, which could put a patient in peril if the nanoparticles were zapped away from the tumor because the aberrant heating could destroy healthy tissue.

Now the Wake Forest Baptist researchers have shown for the first time that it is possible to make the particles visible in the MRI scanner to allow imaging and heating at the same time. By loading the MWCNT particles with iron, they become visible in an MRI scanner. Using tissue containing mouse tumors, they showed that these iron-containing MWCNT particles could destroy the tumors when hit with a laser. "To find the exact location of the nanoparticle in the human body is very important to the treatment,” said Xuanfeng Ding, M.S., who presented the research at the meeting. "It is really exciting to watch the tumor labeled with the nanotubes begin to shrink after the treatment.”

An earlier study by the same group showed that laser-induced thermal therapy using a closely related nanoparticle actually increased the long-term survival of mice with tumors. The next step in this project, according to the investigators, is to see if the iron-loaded nanoparticles can do the same thing. If the work proves successful, it may one day help people with cancer, though the technology would have to prove safe and effective in clinical trials.

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Wake Forest University Baptist Medical Center