Walczak and Janowski teamed with colleagues including Monica Pearl, M.D., an associate professor of radiology practicing in the Division of Interventional Neuroradiology, who specializes in intra-arterial procedures. Usually the procedure is performed using an X-ray image as a guide, but that approach ruled out watching injected stem cells’ movements and making adjustments in real time.

In their experiments, after placing the catheter under X-ray guidance, they transferred anesthetized dog and pig subjects to an MRI machine, where images were taken every few seconds throughout the procedure. Once the catheter was in the brain, Pearl pre-injected small amounts of a harmless contrast agent that included iron oxide and could be detected on the MRI. “By using MRI to see in real time where the contrast agent went, we could predict where injected stem cells would go and make adjustments to the catheter placement, if needed,” says Janowski. Adds Jeff Bulte, Ph.D., a professor of radiology who participated in the study, “It’s like having GPS guidance in your car to help you stay on the right route, instead of only finding out you’re lost when you arrive at the wrong place.”


The team then injected both small stem cells (glial progenitor cells from the brain) and large mesenchymal stem cells from bone marrow into the animals under MRI, and found that in both cases, the pre-injected contrast agent and MRI allowed them to accurately predict where the cells would end up. They could also tell whether clumps of cells were forming in arteries and, if so, possibly intervene to avoid letting the clumps grow large enough to cut off blood flow and pose a danger. “If further research confirms our progress, we think this procedure could be a big step forward in precision medicine, allowing doctors to deliver stem cells or medications exactly where they’re needed for each patient,” says Walczak. The research team is planning to test the procedure in animals as a treatment for stroke and cancer, delivering both medications and stem cells while the catheter is in place.

Other authors on the paper are Joanna Wojtkiewicz, Aleksandra Habich, Piotr Holak, Zbigniew Adamiak and Wojciech Maksymowicz of the University of Warmia and Mazury in Poland; Adam Nowakowski and Barbara Lukomska of the Mossakowski Medical Research Center in Poland; Jiadi Xu of the Kennedy Krieger Institute; and Moussa Chehade and Philippe Gailloud of Johns Hopkins University.

The study was funded by the National Institute of Neurological Disorders and Stroke (grant numbers NS076573, NS045062, NS081544), the Maryland Stem Cell Research Fund, the Department of Defense (grant number PT120368), the Polish National Science Centre (grant number NCN 2012/07/B/NZ4/01427), the National Centre for Research and Development, and a Mobility Plus Fellowship from the Polish Ministry of Science and Higher Education.

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