Tumour cell toxicity of intracellular hyperthermia mediated by magnetic nanoparticles.

Intracellular hyperthermia is a process by which malignant cells can be selectively killed by heat generated by nanomediators located inside the cell. Here we show that maghemite anionic nanoparticles are efficiently captured by human prostatic tumor cells (PC3) and concentrate within intracellular vesicles. When submitted to an alternative magnetic field, maghemite nanocrystals generate heat from the cell inside, inducing a temperature elevation of eight degree in a loose pellet of 20 million magnetically labeled cells. We demonstrate that this heating modality was as lethal as external waterbath heating. A one hour AC magnetic field (700 kHz-31 mT) exposure of the magnetically labeled cells killed 44% of the cells. Interestingly, more than 80% of the cells were killed after being submitted twice to the magnetic field. Finally, when magnetic cells coexist with non magnetic ones, the same proportions of cells were damaged for both populations, after magnetic field exposure. These findings pave the way for an efficient cell killing mediated by intracellular magnetic hyperthermia.