An interdisciplinary team of Stanford researchers has discovered a new mechanism for tracking stem cells after transplantation, in a breakthrough that may have broad implications for the future of effective stem cell therapy.

While stem cell transplants offer a more permanent and natural solution than traditional artificial implants, doctors have historically been unable to track the cells to see if they had taken hold successfully or instead died or migrated away.

After marking stem cells with the anemia treatment ferumoxytol, however, the researchers found that they were able to monitor the cells’ progress through the body for over four weeks through non-invasive MRI scans.

“Metallic implants are much more prone to cause deadly allergies and discomfort than stem cell transplants, so I’m very excited [by our discovery and its implications],” said Fanny Chapelin, a research associate and the paper’s co-author.

Chapelin noted that marking the cells outside the body also eliminates risks posed by manipulating the stem cells between harvesting and transplantation.

However, the tracking mechanism still faces several limitations – such as diminished contrast when applied to larger areas of tissue or to darker body parts like the lungs – and, while testing on new markers may resolve those issues, widespread application to human subjects may still be over a decade away.