Clinical magnetic resonance imaging (MRI) systems can be used to direct cancer-killing cells towards tumours and reduce their growth in mice, reports a study published in Nature Communications this week. The findings suggest that magnetic fields generated by MRI systems can target specific cells for therapeutic purposes.

MRI scanners, which are commonly used in hospitals, employ strong magnetic fields to create high-resolution anatomical images, which are useful for locating tumours in the body. Munnita Muthana, Aneurin Kennerley and colleagues take mouse immune cells carrying a virus that selectively infects and kills tumour cells and make them take up iron oxide nanoparticles. These magnetized immune cells are then injected into mice with prostate tumours. Using an MRI scanner to create pulsed magnetic field gradients, the team then steered the cancer-killing cells to a prostate cancer, or to cancer that had spread to the lung, with the overall effect of reduced prostate tumour growth.

Although existing clinical MRI scanners could potentially create such magnetic fields, it is currently unclear whether this approach might work in humans.