Thanks to advances in stem cell therapy, it is now possible to use engineered white blood cells to fight diseases such as HIV within the human body. When such treatments are being developed, however, it can be difficult to track where the introduced cells travel within a patient’s system, and how many of them make it to their target. Now, thanks to research being carried out at the University of Edinburgh's Centre for Cardiovascular Science, those cells can be magnetically labeled.

Vascular surgeon Jennifer Richards led a team that introduced tiny magnetic iron oxide particles into white blood cells (also known as immune cells). Six test subjects were then given separate thigh muscle injections of the magnetically labeled cells, unlabeled white blood cells, and just the magnetic material. Up to seven days later, the labeled cells still showed up on MRI (magnetic resonance imaging) scans of the subjects. By contrast, other methods of cell-labeling only allow the cells to be tracked for a maximum of a few hours, or expose the patient to radiation – which MRI does not.

The magnetically-labeled cells so far appear to be harmless to the recipients, as two test subjects were given increasingly large doses of the cells through a vein, and showed no adverse effects.

Additionally, the cells are still able to serve their immune function. When the labeled cells were injected into a subject with an inflamed area on their thigh, they moved to that area as they normally would. Nonetheless, Richards has stated that more human tests will be required before the magnetic labeling of blood cells is able to be widely practiced.

A paper on the research was recently published in the journal Circulation: Cardiovascular Imaging.