Older mice 'live longer when blood mixed with young'

Mice Living In Colorful Mouse Apartments, Condos of Plastic Cups
Scientists remain unsure how mixing blood systems of mice rejuvenates elder rodents - James Brey

Old animals live longer when their blood system is joined to a younger animal’s, scientists have shown in a breakthrough which hints at how to slow down ageing.

Throughout history, cultures across the globe have extolled the properties of youthful blood, with children sacrificed and the blood of young warriors drunk by their conquerors.

It was even rumoured that the North Korean dictator Kim Jong-il was injected with blood from healthy young virgins to slow the ageing process.

Now, scientists have shown that surgically joining the circulatory system of a four-month-old mouse to a two-year-old mouse, for three months, slowed down ageing at the cellular level, and extended the lifespan of the older animal by 10 per cent.

The rejuvenation effect could still be seen even after two months of detachment, adding around 12 weeks to the usual three-year lifespan of the older mouse.

If the effect was replicated in humans by pairing a 50-year-old’s circulatory system to an 18-year-old’s, it would increase a lifespan by eight years.

‘Unethical’ to use procedure in humans

Although it would not be ethical or practical to carry out the procedure in humans, scientists at Duke University Medical Centre said it shows that the young benefit from a cocktail of components and chemicals in their blood that contributes to vitality.

If those factors could be isolated and synthesised, they could be used as therapies to speed healing, rejuvenate the body and add years to an individual’s life.

“This is the first evidence that the process can slow the pace of ageing, which is coupled with the extension in lifespan and health,” said Dr James White, the senior author of the study and the assistant professor of medicine and cell biology at Duke University School of Medicine.

“Our work points to a need to explore what factors in the circulation of youthful blood cause this anti-ageing phenomenon.

“The elements that are driving this are what’s important, and they are not yet known. Are they proteins or metabolites? Is it new cells that the young mouse is providing, or does the young mouse simply buffer the old, pro-ageing blood? This is what we hope to learn next.”

Earlier studies had shown that pairing the mice for three weeks helped older animals become more active and animated, and triggered some tissue regeneration. Experts said the new study showed that longer attachment brought bigger benefits and increased lifespan.

Procedure’s effects similar to calorie restriction

At the cellular level, the procedure drastically reduced the epigenetic age of blood and liver tissue, and showed gene expression changes similar to lifespan-extending interventions such as calorie restriction.

In 2014, scientists at Stanford University discovered that young blood “recharges” the brain, forms new blood vessels and improves memory and learning in animals in a breakthrough that experts hoped would lead to new therapies for Alzheimer’s disease.

In the same year, Harvard University discovered that a “youth protein” known as GDF11 is present in the bloodstream in large quantities when we are young but peters out as we age.

However, when the blood plasma of young people was tested on a small trial of Alzheimer’s patients, it produced no lasting benefits.

The team is now planning to study young blood to see if they can pinpoint what is driving the youthful effect, in the hope that it could be turned into a drug to slow down ageing and help combat diseases of old age.

The research was published in the journal Nature Aging.