Turning blood cells into Trojan Horses

Scientists in Italy have found a way to boost the power of MRI tracer chemicals - by hiding them inside a patient's own cells.

A major problem with contrast agents like iron oxide nanoparticles, which are designed to enhance the signals scanners can pick up from certain tissues is that the agents are rapidly diluted out or picked up and excreted from the body.  Now University of Urbino researcher Mauro Magnani and his team, writing in the Journal of Nanoscience and Nanotechnology, has found a solution.

The researchers first incubate a sample of a patient's red blood cells in a solution containing the nanoparticle-contrast agent.  Crucially the concentration of the solution is adjusted to make it more dilute than blood plasma.  This makes the cells swell up as water moves into them due to the process of osmosis.  As this happens the cell membranes become leaky allowing the iron oxide nanoparticles to enter.  When the concentration is later returned to normal the cells shrink but the nanoparticles remain trapped inside.

The blood can then be re-infused into the patient where the red cells, carrying their contrast cargo, remain in circulation for the rest of their normal lifetime, which can be up to 120 days.  This should enable doctors to make repeated measurements on patients over time, but without needing to top up the contrast.  It could prove useful in spotting signs of internal bleeding, for instance post-surgery.

The italian team have signed a deal with Phillips research to pursue the work, which has not yet been tested on humans although the contrast agent itself has and is safe.