Aging cells

Clumps of protein associated with such neurodegenerative diseases as Alzheimer’s are present in stem cells in young mouse brains, a finding that could help Stanford scientists figure out how to reboot aging neural stem cells to maintain brain health.

The clumps, called aggregates, form when damaged or diseased proteins in neural stem cells bunch together. They collect in cellular trash bins known as lysosomes, which “digest” and eliminate them. As cells age, however, they are less able to dispose of aggregates, which impedes their ability to make new neurons.

Anne Brunet, PhD, professor of genetics and senior author of a paper describing the research published March 15 in Science, said researchers were surprised by the finding because resting young cells were understood to be “a really pristine cell type just waiting for activation.”

“But now we’ve learned that they have more protein aggregates than activated stem cells, and that these aggregates continue to accumulate as the cells age,” she said. “If we remove these aggregates, we can improve the cells’ ability to activate and make new neurons,” bringing aging neural stem cells “back to life,” and, perhaps, turning back the clock on such aging effects as memory loss and difficulty discerning smells.