Over the last decade, scientists have persuasively shown that brain cells replicate, a notion that was, at first, controversial. They are now exploring how the cells replicate, a process called neurogenesis, and seeking ways to improve the process when it appears to slow or stop altogether, for example, in older people or those with Alzheimer's disease.
Duke researchers recently showed for the first time that putting two specific types of neural cells directly into an aging brain can kick-start creation of brain cells linked to learning and memory. The group harvested two types of cells from the spinal cords of rats and implanted them in the hippocampi of aging rats. The hippocampus, an area of the brain linked to memory formation and storage, as well as depression and neurodegenerative diseases such as Alzheimer's, is where neuron-forming stem cells perform much of the cell replication found in humans.
After three weeks, researchers saw an increase in neurogenesis in the rats that received the cell implants, compared with rats that did not receive any treatment and rats that received implantation surgery but not stem cells.
The researchers view the finding as an important step in working toward therapies for humans. In older people and people with Alzheimer's disease, "neural stem cells are sitting there but not dividing, so they are not making new neurons," says Ashok K. Shetty, professor of neurosurgery at Duke and a medical research scientist at the Durham Veterans Affairs Medical Center. "We hope that by making more neurons, we can improve learning and memory" in patients.
The results of their work appear in the journal Stem Cells.