Stem Cells Entering Heart can be Tracked with Nano-‘Hitchhikers,’ Scientists Say

The technique is described in a study published March 20 in Science Translational Medicine. Testing the new imaging method in humans is probably three to five years off.

Human and animal trials in which stem cells were injected into cardiac tissue to treat severe heart attacks or substantial heart failure have largely yielded poor results, said Sam Gambhir, PhD, MD, senior author of the study and professor and chair of radiology. “We’re arguing that the failure is at least partly due to faulty initial placement,” he said. “You can use ultrasound to visualize the needle through which you deliver stem cells to the heart. But once those cells leave the needle, you’ve lost track of them.”

As a result, key questions go unanswered: Did the cells actually get to the heart wall? If they did, did they stay there, or did they diffuse away from the heart? If they got there and remained there, for how long did they stay alive? Did they replicate and develop into heart tissue?

“All stem cell researchers want to get the cells to the target site, but up until now they’ve had to shoot blindly,” said Gambhir, who is also the Virginia and D.K. Ludwig Professor in Cancer Research and director of the Molecular Imaging Program at Stanford. “With this new technology, they wouldn’t have to. For the first time, they would be able to observe in real time exactly where the stem cells they’ve injected are going and monitor them afterward. If you inject stem cells into a person and don’t see improvement, this technique could help you figure out why and tweak your approach to make the therapy better.”