Powerful new imaging technology is a game-changer for stem cell therapies

Image generated by magnetic particle imaging, being developed by Steven Conolly of UC Berkeley

When you read the words “physics” and “engineering”, I bet the first thing that comes to mind is NOT stem cell research. But it turns out the fields of physics and engineering are making possible the development of magnetic particle imaging, or MPI, a new imaging technology that could be a game-changer in the advancement of stem cell therapies.

Steven Conolly, a CIRM grantee whose UC Berkeley lab is pioneering MPI, spoke to the CIRM governing board at its May 24th meeting (watch the video of his talk here). To introduce MPI, Conolly first spoke about a key challenge in the stem cell field:

We need to get cells into the affected organ, we need to create a niche where they can survive, and of course we want them to improve the function of that organ and we want them to stay stably, say in heart failure, for months and years. The role of imaging is to see this in vivo. Of course we start with small animals but it would be wonderful to do that in individual patients to figure out how the cells are improving function. You can imagine once you inject cells there’s a very difficult debugging problem: Were those cells removed by the liver? Were they removed by [the immune system]? Were they filtered out in the lungs? All these questions are difficult to answer if you can’t see through the body.

Knowing where stem cells go after they are injected into patients will be critical for convincing the FDA that the cells are both safe and effective. The problem is that currently available imaging technologies such as x-rays, ultrasound, bioluminescence, CT scans, and MRI aren’t adequate for the task. Some can’t see deep enough into tissue while others aren’t sensitive enough or require radiation.

That’s where MPI comes in, which is 200 times more sensitive than MRI. It’s something akin to those metal detectors you see beachcombers scanning along the sand. In this case, the “metal” is FDA-approved iron oxide nanoparticles that are mixed with the cells before they are injected into the body. The MPI scanner’s magnetic field detects the nanoparticles and produces an image of where the cells are in the body and how many of them there are.

With the help of a CIRM Tools and Technology grant, Conolly’s lab has been steadily building several prototype MPI scanners. He drew comparisons of his current research with his early career:

This is, in my opinion, similar to the late 1970’s in the field of MRI when we were just developing it. There weren’t any commercial scanners available and the physics, the biology, the methodology, the nanoparticles, everything is still up for grabs. It’s a very, very exciting area of research.

Conolly pointed out that this CIRM-supported research has led to additional funding for other applications of MPI:

I couldn’t have gotten a NIH grant without the seed funding from CIRM to get the technology up and running

In collaboration with his colleague David Shaffer (who also has a Tools & Technologies Award), Conolly is planning to use MPI to track cells in a mouse model of Parkinson’s disease. MPI imaging could be particularly useful for a future stem cell-based Parkinson’s therapy since the neurons that die off in the disease are located deep within the brain. The efforts of Dr. Conolly were not lost on Greg Wasson, a board member of the Parkinson’s Action Network who has lived with Parkinson’s for 17 years and also spoke to the CIRM governing board (watch his video here). He acknowledged:

the many research scientists like Dr. Conolly for their hard work and dedication in the fight to find new therapies for Parkinson’s. You have made the promise of Prop 71 a working reality that will continue to bring benefits to [my wife] AJ, me and patients around the world.

 T.D.