"It’s about healthy living, not longer living,”

Ian Sample asks at The Guardian,

Can we reverse the aging process by putting young blood into older people?

...Neurons in ageing brains lose their connections and start to die off; ultimately, the brain shrinks and becomes less effective. A region called the hippocampus, crucial for memory and learning, is one of the first to deteriorate with age, causing people’s memories and thought processes to falter.

Old mice that received young blood experienced a burst of brain cell growth in the hippocampus. They had three to four times as many newborn neurons as their counterparts. But that was not all: old blood had the opposite effect on the brains of young mice, stalling the birth of new neurons and leaving them looking old before their time.

In October 2014, Wyss-Coray launched the first human trial of young blood. At Stanford School of Medicine, infusions of blood plasma from young people are being given to older people with Alzheimer’s disease. The results are expected at the end of the year. It is the greatest test yet for the medical potential of young blood.

Tony Wyss-Coray is a professor of neurology at Stanford university Photograph: Tony Wyss-Coray

...Progress in science takes more than hope. With no knowledge of blood groups or coagulation factors, the early transfusion experiments were deadly. Before long, the procedure was banned, first in France, and then England. The pope endorsed the bans in 1679, and transfusion all but ceased for a century. When advances in medicine allowed its return, the emphasis was on healing the sick, not helping the aged.

...The body’s tissues need stem cells to remain healthy and in good working order, but in older people, stem cells stop doing their job – this is why wounds heal so much slower as we age. Rando wondered whether stem cells failed in old animals because they no longer got the right signals. What if something in young blood turned them back on again? Perhaps he could make older people heal as fast as young ones.

...Scientists in Rando’s lab joined old and young mice for five weeks and looked at how well they repaired little tears in muscle tissue. The young blood activated stem cells in the old mice that swiftly regenerated their damaged muscles. The young mice, however, fared worse for their exposure to old blood. Their stem cells became sluggish, and their tissues healed more slowly. Rando saw hints of another effect too, but needed more evidence before he could publish: the old mice had begun to grow new brain cells.

Saul Villeda carried out the early research on the restorative properties of young blood. Photograph: Saul Villeda

Villeda looked at how young blood altered the way genes are expressed in old mice. He noticed a stark difference among genes that help neural connections strengthen and weaken, a process crucial for learning and memory. In normal ageing, the genes that control this “synaptic plasticity” become less active. Young plasma jabs ramped the gene activity back up again.

Wyss-Coray and Villeda were not the only scientists making headway in this area. Two members of the team behind Rando’s 2005 paper on stem cells had moved to the University of California, Berkeley, where they found that oxytocin, often called the love hormone, rejuvenated old muscle tissue. Another, Amy Wagers, had begun working at Harvard. She showed that when given young plasma, old mice regained their stamina. On a treadmill, the treated mice ran for an hour on average, compared with only 35 minutes for untreated ones.

The studies all point in one direction. Among the hundreds of substances found in blood are proteins that keep tissues youthful, and proteins that make them more aged. Wyss-Coray has a hypothesis: when we are born, our blood is awash with proteins that help our tissues grow and heal. In adulthood, the levels of these proteins plummet. The tissues that secrete them might produce less because they get old and wear out, or the levels might be suppressed by an active genetic programme. Either way, as these pro-youthful proteins vanish from the blood, tissues around the body start to deteriorate. The body responds by releasing pro-inflammatory proteins, which build up in the blood, causing chronic inflammation that damages cells and accelerates ageing.
Read more here.