The Stanford team infused fluid from 10-week-old mice into the brains of 18-month-old mice for seven days and found that the older mice remembered better to associate a small electric shock with a noise and to a flashing light.
Closer examination showed that the liquid had “awakened” the processes that regenerate neurons and myelin – the fat that protects nerve cells in the hippocampus, the brain’s memory centre.
Basically, the scientists think they know which part of the fluid is causing the effect: a protein called serum response factor (SRF) that declines in older mice.
When they used a growth factor called Fgf17 to increase SRF levels, the older mice showed the same improvements seen with the youthful infusions, suggesting that Fgf17 could be used as a treatment to rejuvenate aging brains.
The aging process is “malleable”
Dr Tony Wyss-Coray, of Stanford Medical School in California, said research has shown the aging process is “malleable” and that improving the environment in which neurons live can be a better approach than targeting the cells themselves.
And it’s not just in the brain that the rejuvenating properties of youth show promise. The effect seems to work from head to tail.
Earlier this month, the Quadram Institute in Norwich showed that transplanting faecal microbes from young mice into old mice reversed signs of aging in the gut, eyes and brain.
In contrast, when microbes from old mice were transplanted into young mice, it induced inflammation in the brain, depleting a key protein needed for normal sight.
The team is now working to understand how long these positive effects last and how they may impact organs away from the gut.
Dr Aimee Parker, lead author of the study at the Quadram Institute, said: “We were thrilled to discover that by altering the gut microbiota of older adults, we could rescue indicators of age-associated decline commonly seen in degenerative diseases of the eye and brain. .”
Although the latest studies have been performed on mice, these advances mark a significant shift in the field of aging that could soon revolutionize therapies.
Experiments even show that young blood itself can reverse the aging process, possibly even curing Alzheimer’s disease.
Historically, cultures have revered the blood of youth. It was even rumored that Kim Jong-il, the former North Korean dictator, injected himself with the blood of healthy young virgins to slow down the aging process.
The first hint that young blood might rejuvenate came in 2005 when Stanford conducted a macabre experiment by stitching old and young mice together so they shared a circulatory system.
After a month, the scientists discovered that the older mouse’s liver and muscles had begun to regenerate.
In 2014, Harvard University found that young blood also “recharges” the brain, triggering the formation of new blood vessels and improving memory and learning in mice.
The team even identified a “youth protein” that is responsible for keeping the brain and muscles young and strong.
The protein, known as GDF11, is present in the blood in large quantities when we are young, but disappears with age.
Increasing levels of the GDF11 protein in mice has been shown to improve the function of all organs in the body, including the heart.
$8,000 for teenage blood plasma
However, the field is not without controversy. In 2019, an American start-up called Ambrosia that offered teenage blood plasma to Silicon Valley billionaires for $8,000 a liter was forced to close after the FDA warned against the procedure.
In 2017, Ambrosia began a clinical trial designed to find out what happens when adult veins are filled with blood from younger people, but never published the results.
It is still hoped that one day such procedures will be used in humans.
In 2019, Wyss-Coray’s biotech company Alkahest reported the results of a small six-month trial that saw 40 Alzheimer’s disease patients infused with a special blend of human plasma, containing more proteins that disappear with age.
This seemed to halt their expected mental decline. The company also has similar trials underway for Parkinson’s disease, age-related macular degeneration, inflammatory diseases and end-stage kidney disease.
Harvard spin-off company Elevian is also working to produce enough GDF11 to begin human trials exploring whether it can help people recover from strokes.
“Our research suggests that by targeting the fundamental and common underlying mechanisms of aging as opposed to a specific disease, it may be possible to treat and prevent several age-related diseases,” said Dr Mark Allen, CEO and co-founder of Elevian.
It may only be a few years before the “youth transplants” finally move from the pages of gothic horror novels to the clinic. It remains to be seen whether patients will feel disgusted by such vampire procedures.