Stem cell treatments hold great promise for treating a range of medical conditions that afflict the human body, but delivering them to the precise location of disease, damage, or injury has been challenging. Now, a team of scientists has succeeded in delivering stem cells to the brain through a catheter threaded into an artery with remarkable precision using real-time guidance with MRI.
Published in the Journal of Cerebral Blood Flow and Metabolism, the work describes tests conducted on anesthetized pigs and dogs. The hope is that this will pave the way for human trials of a technique that could prove useful in treating stroke, Parkinson’s and other disorders of the central nervous system.
Despite the promise of many stem cell therapies, many clinical trials fail, likely because we lack the tools to precisely deliver the stem cells to the target tissue, explains Piotr Walczak, M.D., Ph.D., of the Institute for Cell Engineering at Johns Hopkins University School of Medicine. Human stem cells hold great therapeutic promise on account of their ability to metamorphose into any kind of cell. Theoretically, stem cells can be used to regenerate any damaged or diseased tissue in the body, from insulin-producing islet cells in the pancreas to dopamine-making brain cells in patients with Parkinson’s disease.
A decade ago, Japanese Nobel Prize winner Shinya Yamanaka’s research group gave a huge boost to stem cell treatments with their discovery of a technique that could be used to reset mature cells into pluripotent stem cells. This provided an alternative to embryonic stem cells and put to rest the ethical debate about using human embryos. The technique also allowed scientists to create therapeutic stem cells with a matching genetic makeup to the patient, thereby reducing the chances of rejection after infusion or transplantation.
Although many advances have been made in stem cell therapy, some barriers remain, one of which is placing the cells exactly where they are needed. Puncturing a patient’s skull is unpleasant and is a limited approach. Intravenous injection of stem cells scatters them all over the body, with very few making it to the precise location where they are needed.
The scientists at Johns Hopkins have developed this new technique to overcome these hurdles. Using a catheter threaded into the patient’s artery, usually through a leg, the scientists will be able to follow the path of the blood vessel and reach an otherwise inaccessible area of the patient’s brain. This technique is already used to repair vessels in the brain under guidance by X-ray.
To monitor catheter placement and watch the movement of the injected stem cells, Walczak and his colleagues Miroslaw Janowski, M.D., Ph.D. and Monica Pearl, M.D. placed the animal (dog or pig) in an MRI machine and captured images every few seconds. The passage of a harmless contrast agent was then viewed in real-time, indicating to the scientists that stem cells could be similarly monitored. “It’s like having GPS on your car guiding you to the correct route,” says Jeff Bulte, Ph.D., another participating scientist on the study.
The technique also allowed the scientists to break up any clumps of cells that might be forming and posing a danger to cutting off blood flow. With further progress, this procedure could be a giant step forward in precision medicine. As the next step, the team plans to continue tests in animals by delivering treatments for cancer and stroke as well as stem cells through the catheter.