Mice with the kind of brain damage caused by strokes or cerebral palsy received implants of stem cells that resulted in the spontaneous replacement of many of the missing cells, according to Evan Snyder, a neurologist at the Harvard Medical School, who led the research. In other experiments, stem cells unexpectedly rescued the injured nerve cells of aged mice whose brains were compromised by the equivalent of Parkinson’s disease and normal aging in humans. “If the experiments had been done in humans, it is difficult to know if we would have gotten the same results,” Snyder admits. “But I think there’s a possibility that stem cells might help re-form some of the lost connections between cells sufficiently to promote restoration of function.” Snyder was surprised to see that stem cells not only replaced missing brain tissue, but provided protection for cells disabled by age and diseases. “It’s not unreasonable to think that in humans the early implantation of stem cells – because of partnerships they form with host cells – might forestall or even pre-empt degenerative diseases such as Parkinson’s and Alzheimer’s,” Snyder says. “Perhaps, attacks by such diseases could be made less ferocious and mild enough for patients to adapt.”