Researchers may have found the fountain of youth — for mice

White mouse

Independent studies report blood from young mice rejuvenates older mice

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The fountain of youth may be within your reach — if you are a mouse, that is.

Researchers at Stanford, the University of California (San Francisco) and Harvard have all recently released studies reporting that injecting older mice with the blood of younger mice changes the genetic activity and the behavior of the older mice.

“All of this is just a little bit insane,” says Saul Villeda, a faculty fellow at the University of California, San Francisco, who is the lead author of a study reported in the journal Nature Medicine.

“These studies all came out at the same time from independent researchers,” Villeda says, with some amazement. “Our own study was initiated at Stanford in the lab of Dr. Tony Wyss-Coray and continued in my own lab when I started about two years ago. We were able to see the same effect in two independent places. Add to that now the Harvard groups and we have multiple institutions across the country all seeing similar rejuvenating effects. It's just wild.”

In 2011, Villeda, Wyss-Coray and their colleagues published a paper in the journal Nature showing that young blood reduced age related decline in the stem cells of older mice.

“We also looked at the converse,” Villeda says, “which was the effect of old blood on a young animal — and we saw impairments in learning and memory.”

So, he says, everyone started asking, ‘What about in an old organism, in an older mouse? Can the opposite be true? Can you actually rejuvenate things like learning and memory?’

In their recent paper, Villeda and his colleagues report changes in both the neural circuitry in the brains of older mice and their behavior. When they injected older mice with younger blood, the older mice performed better on learning and memory tests than older mice who had not received the infusion.

Simultaneously, researchers at Harvard were finding that a blood protein called GDF11 revived stem cells in the muscles of older mice, making the older mice stronger and increasing their endurance.

What is in the younger blood that is rejuvenating the older mice? Villeda thinks it’s probably a combination of factors.

“There's so much that's still unknown,” he says. “But we do know that there is something in plasma” — either one factor or some combination of factors — “that can definitely have some rejuvenating effects, at least on cognition.”

As we get older, he explains, our brains show either a decrease in genes or a decrease in the activation of certain genes. “All of a sudden,” he says, “you add young blood and it's like an 'on' switch. You increase the activity of these genes, and that leads to these incredible changes at a cellular level throughout this region [the hippocampus] of the brain and we get increased cognition.”

Now that the public has caught on to their research, Villeda is urging patience with translating these findings to humans. There is still a long list of unanswered questions.

“How many times do we need the exposure? How long-lasting are the effects? Are there any adverse effects? All of these are things that still need to be investigated,” Villeda says.

Besides: “These studies were done in mice. We were able to reverse some signs of aging in a mouse model. Many times before, there are great findings in mice that don't necessarily translate to humans. Humans are much more complex, so we may have to come up with different strategies.”

But, he says, his colleague Dr. Wyss-Coray has co-founded a biotech company called Alkahest, whose goal is to try to apply the idea of using young plasma in human therapeutic treatment.

“So we're definitely trying to go as fast as we can in terms of bridging these findings [to humans],” he says. “But we’re still saying, ‘Calm down. Don’t get too excited.’”

This story is based on an interview by our partner Science Friday, a weekly radio show and website covering science, technology and other cool stuff.

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