Injecting stem cells into the brain has serious risks. In the a case of patients who have experienced traumatic brain injury (TBI), intracranial injections of stem cells can cause intracranial hemorrhage. Also, the injected stem cells often fail to find their way to the injured parts of the brain. Therefore, you have a high-risk procedure that may yield few benefits.
However a new technique for getting stem cells into the brain has been designed and tested by Paul Yarowsky and his colleagues at the University of Maryland and the Veterans Administration Maryland Healthcare System.
Yarowsky and his coworkers labeled human neural progenitor cells with iron oxide “superparamagnetic nanoparticles” and directed team to the site of a brain injury by means of a magnetic field.
They tested this technique in rats that had suffered TBI and discovered that the delivery methods has no deleterious effects on the viability of the stem cells and not only increases stem cell homing to the site of injury, but also increased stem cell retention.
“Magnetic cell targeting is ideally suited to augmenting cell therapies. The external magnetic field and field gradient can guide cells to sites of injury and, using MRI, the iron-oxide superparamagnetic nanoparticles can be visualized as they travel to the site of injury. The goal when employing this method is not only guiding the particles to the site of injury, but also enhancing entry into the brain and the subsequent retention of the transplanted cells,” said Yarowsky.
The intensity of the magnetic field neither affects the viability of the cells in culture, nor their proliferation nor differentiation. This is also the case when the cells are loaded with iron oxide nanoparticles. These results suggest that this is indeed a promising technique for cell delivery in TBI patients and might also be useful for treating other neurological injuries and neurodegenerative diseases as well.
A critical question is, “what happens to the cells when the magnetic field is no longer present?”. Also, the patient must wear a magnetic hat in order to subject the cells to a magnetic field, but what is the minimum time the patient must wear it in order for the procedure to be successful? All of these questions must be addressed to some degree if they this technique is to be properly understood. For now, Yarowsky and his colleagues assume that the optimized magnetic intensity observed in experiments with rodents must be extrapolated to larger animals, which may or may not be a legitimate extrapolation. Until larger animal experiments are conducted, this will remain a speculation.
Even though a good deal of work remains to be done, Yarowsky and his colleagues are still optimistic that their ingenious iron oxide nanoparticle procedure has promise and might, some day, be translated to human clinical trials.
This work was published in the journal Cell Transplantation, 21 September 2015.