A "fountain of youth" that sustains the production of new neurons in the brains of rodents is also believed to be present in the human brain, a new study has found.
The finding by researchers at the Duke University Medical Centre explains why stem cells by themselves can't generate neurons in a lab dish, a major roadblock in using these stem cells for injury repair.
"We believe these findings will have important implications for human therapy," Chay Kuo, M.D., Ph.D., George Brumley Jr. assistant professor of Cell Biology, Pediatrics and Neurobiology, and senior author of the study, said.
The scientists found that neighbouring "epithelial-like" ependymal cells - not stem cells themselves - maintain a special structure that keeps neural stem cells "neurogenic," able to make new neurons.
Currently, when neural stem cells are harvested for growth in culture, however, the ependymal cells are not removed along with them.
In a series of experiments, the researchers found that the generation of new neurons depended on what Kuo calls the "ugly sibling" of the stem cells, the ependymal cell that has long, moving, hair-like cilia that cover its surface.
Kuo decided to study these cells because the lateral ventricles in the brain, where adult neural stem cells reside, are also the last area of a developing brain that grows ependymal cells.
"There is this fountain of youth inside the adult brain that actively makes new neurons," Kuo said.
"Yet we don't know how this fountain is constructed or maintained," he added.
The study was published in the July issue of Neuron.