A team of nanoscientists has used a new type of magnetic nanoparticle to “cook” tumor cells in laboratory mice, successfully eradicating all traces of the cancer, and with no apparent side-effects.
The treatment of tumors and cancer cells via nanomedicine has had a few, promising successes in recent years, but with some drawbacks including large dosage size and allergic reactions in some patients. But now, a team of nanomedical researchers has devised a new method for “cooking” tumor cells using specially designed, magnetic nanoparticles.
Using heat to cook tumor cells — known as hyperthermia — is not a new idea (all cells die at around 43°C), but the challenge has been to control the “cooking” of the cancer cells without damaging nearby healthy cells. Also, in previous nanotech experiments, doses of injected, magnetic nanoparticles had been relatively large — risking moderate to severe allergic reactions in patients. Further, earlier iron-oxide particle experiments produced “poor conversion efficiencies” and have hindered practical applications.
The new technique relies on a “core-shell” configuration of the magnetic particles in which a softer, magnetic shell, composed of one magnetic compound, encapsulates a harder, magnetic core composed o f a different magnetic compound (see top/bottom diagrams). This design takes advantage of a molecular phenomenon called exchange coupling which causes the particles to interact far more strongly under a magnetic field than conventional magnetic nanoparticles.
In the experiments, mice with grafted brain tumor cells in their abdomens were injected with the core-shell particles and then placed within a induction coil device that produces a magnetic field of sufficient strength. Healthy cells are not impacted by the external magnetic field, but the tumor cells containing the core-shell nanoparticles are; the particles responded to the alternating field by generating up to ten time the amount of heat previously generated by conventional particles.
Biopsies of the mouse tissue showed that all traces of the cancer had disappeared and no side-effects were observed.
What’s more, the dosage of nanoparticles used in the treatment was only 10% of that used in previous magnetic nanoparticle experiments. This lower dosage may also minimize immune responses to the particles.
For comparison, the researchers also treated a group of mice with a conventional anti-cancer drug called doxorubicin. Initially, this drug treatment was able to shrink the tumors, but they grew back up to four times their original size by the end of the trial. Further tests with conventional (non core-shell type) iron-oxide nanoparticles showed no significant change in tumor size.
The breakthrough experiments were conducted by nanoscientists Jae-Hyun Lee, Jinwoo Cheon and colleagues of Yonsei University in Seoul, and reported in the June 26 issue of Nature Nanotechnology under the title: ‘Exchange-coupled magnetic nanoparticles for efficient heat induction‘
Previous experiments with specially coated nanoparticles on cancerous tissue — specifically prostate cancer — have showed real promise. With this most recent success, nanotech applications in cancer treatments are becoming leading contenders in the fight against cancer — with potentially greater results than gene therapy. But as always, such experimental results will need to be duplicated by others and the method further refined before it becomes an available treatment option.
Other applications of nanoparticle technology include drug release and remote control of single cell functions.
Images/diagrams: (from the published paper by Jae-Hyun Lee et al, press contact: Jinwoo Cheon – Yonsei Univ., Seoul, and, Korea Basic Science Institute, Daejeon.