For the last decade, the lab of Tracey McIntosh, PhD, director of Penn's Head Injury Center and professor of neurosurgery, bioengineering, and pharmacology, has been investigating neural implants to one day correct brain injuries, which affect nearly two million people every year. For the most part, neuronal transplantation has concentrated on stroke, neurodegenerative disorders, and spinal-cord injuries. Last year, hNT cells -immortalized human nerve cells developed at Penn ten years ago - were successfully transplanted into a stroke patient in Pittsburgh. Recent articles in the Journal of Neurosurgery and Journal of Neurotrauma describe ongoing studies in which Penn researchers are studying how implanted hNT cells might improve brain function in an injured rat.
"We found that cells implanted directly adjacent to the injured site 24 hours after the initial trauma survive, appear healthy, and integrate into the host tissue," says Ramesh Raghupathi, PhD, assistant professor of neurosurgery and coauthor on both studies. In one study, 83 percent of the rats had healthy grafts two weeks after the injury. In the second study, 92 percent had healthy grafts at four weeks. Both studies also showed that there was not an enhanced response to the hNT cells by the rat immune system. Both studies, however, did not show an improvement in cognitive skills as measured by a water maze test or in tests of motor function. In hopes of improving rats' performance on these trials, the group's next steps will be to carry out parallel studies with stem cells, inject hNT cells into more than one spot around an injury, and infuse growth factors along with the transplanted cells.