Umbilical cord blood from human newborns, and in particular a single protein contained in it, boosted old mice’s brain function and cognitive performance, new research from Stanford shows.

Human umbilical cord blood can rejuvenate learning and memory in older mice, according to a study by researchers at the Stanford University School of Medicine.

The researchers identified a protein, abundant in human cord blood but decreasingly so with advancing age, that had the same effect when injected into the animals.

The findings could lead to new treatments for age–associated declines in mental ability.

“Neuroscientists have ignored it and are still ignoring it, but to me it’s remarkable that something in your blood can influence the way you think,” said the study’s senior author, Tony Wyss–Coray, PhD, professor of neurology and neurological sciences and a senior research career scientist at the Veterans Affairs Palo Alto Health Care System. The lead author is former postdoctoral scholar Joseph Castellano, PhD, who is now an instructor of neurology and neurological sciences.

The study was published online April 19 in the journal Nature.

In a widely discussed earlier study, Wyss–Coray’s lab showed that direct infusion of young mice’s plasma, the cell–free portion of blood, benefited old mice. Those benefits extended beyond biochemistry and physiology to actual performance on tests of memory and learning, the researchers found.

The new study marks the first demonstration that human plasma can aid older mice’s memory and learning, which both Wyss–Coray and Castellano said would seem to increase the likelihood that it could have a similar beneficial effect in people. It’s also promising from a drug–development standpoint, they suggested, that a single protein appears largely capable of mimicking those benefits.

Comparing blood plasma from 19– to 24–year–olds, 61– to 82–year–olds and umbilical cords, researchers identified age–associated changes in a number of proteins.

These changes, the investigators suspected, might affect a brain structure called the hippocampus, which in both mice and humans is critical for converting experiences into long–term memories. In particular, the hippocampus is essential for helping you remember spatial information, such as how to find your way back to the car you parked in a multilevel structure several hours ago, and information about autobiographical events, such as what you ate for breakfast.

For largely unknown reasons, the hippocampus is especially vulnerable to normal aging, said Wyss–Coray. “With advancing age, the hippocampus degenerates, loses nerve cells and shrinks,” he said. The capacity to learn and remember falters in lockstep. Hippocampal deterioration is also an early manifestation of Alzheimer’s disease.

To distinguish the effects of old, young and “youngest” human blood on hippocampal function, the researchers used immune–deficient laboratory mice that could be given repeated injections of human plasma without experiencing negative immune reactions. Experiments undertaken before injecting human plasma into the mice showed that, like their immune–competent peers, these mice’s hippocampal activity, integrity and regenerative capacity dropped off in old age — indeed, a bit faster.