O Jun. 4, 2007, researchers from the Stanford University School of Medicine announced they had illuminated the path taken by human neural stem cells that were transplanted into the brains of rats and mice, and found that the cells successfully navigate toward areas damaged by stroke.

The research group placed miniscule particles of iron inside stem cells to act as cellular beacons detected by magnetic resonance imaging. With the ability to monitor where the human stem cells go in real time. The findings were published in the the Proceedings of the National Academy of Sciences could eventually make it possible to track human stem cells that are transplanted into the brains of patients.