Neurons Implanted In Stroke-Damaged Brain Tissue Show Function, Say University Of Pittsburgh Researchers

Positron Emission Tomography (PET) scans taken six months after surgery to implant LBS-neurons showed a greater than 10 percent increase in metabolic activity in the damaged parts of some patients' brains compared to scans taken just a week prior to surgery. The increased metabolism corresponds with better performance on standardized stroke tests for behavioral and motor function.

While PET scans taken at 12 months post-surgery showed that metabolism in the implanted area itself had lessened to baseline, the surrounding area in some patients showed maintained or even improved function - perhaps evidence that the LBS-neurons were becoming integrated into the brain.

Results of the study from the first human neuroimplantation trial for chronic stroke appear in the September issue of Neurosurgery.

"These changes in glucose metabolism in the stroke and surrounding brain tissue may represent cellular activity or grafting of the implanted neurons," said Carolyn Cidis Meltzer, M.D., associate professor of radiology and psychiatry and medical director of the University of Pittsburgh Medical Center's PET facility and principal author of the study. "Although this is not direct evidence of synapse formation, it does suggest that the new neurons are being wired into the brain."

Dr. Meltzer and her colleagues performed PET imaging on 11 patients who suffered strokes resulting in persistent motor deficits at least a week before, then six months after implantation surgery. Nine of the original group went through the scans again at 12 months. Metabolism was measured by the uptake of a glucose analog called fluorodeoxyglucose (FDG) by the cells.

After six months, increases of FDG greater than 10 percent were observed in seven of 11 patients. After 12 months, the increase was sustained by three of the 11. In the areas surrounding the stroke, only two of 11 patients showed a greater than 10 percent increase in metabolism at six months, but after a year, five of 11 patients had at least one scan demonstrating a rise in relative metabolism over baseline.

The increased metabolism correlated with positive changes in neurological evaluations (National Institutes of Health stroke scale, European stroke scale) given to the patients during a 52-week period following transplant.

Patients are all part of the first human trial of the effectiveness of neuroimplantation to rep