Young blood helps heal muscles in old mice

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Mice were sewn together in previous blood transfer studies, meaning they shared other body systems and organs too. Now a new, less invasive method keeps organs out of the equation while letting researchers accurately track how much blood is swapped.
Credit: Carolyn A McKeone / Getty Images

Harvesting young blood has some benefits, but won’t stave off the ageing process, researchers have found – at least in mice.

This grim reality was highlighted by a study in Nature, which also described a new method of blood-sharing, allowing researchers to more accurately observe how differently aged blood affects a host’s body.

Irina Conboy, a bioengineer at the University of California, Berkley, and colleagues studied how young blood affected older mice back in 2005.

But their method of blood-sharing, where mice were surgically sutured together in order to share their blood supply, had its complications.

The amount of blood shared between the two animals in this invasive procedure was difficult to track. 

More importantly, the suturing process led to the animals sharing organs and other systems.

The older mouse gained access to a younger immune system, heart, liver and kidneys, while the younger mouse was forced to maintain an older system. This caused the results to reflect more than just the effects of blood transfusion.

Ten years later, Conboy’s team came up with a new method of blood-sharing, this time by way of a catheter leading directly into the jugular and a computer-controlled pump circuit.

This method allows instant blood exchange, in precise and easily-managed amounts, and blocks the sharing of other systems and organs.

During the method’s first outing in the laboratory, mice were pumped with older or younger blood, then tested for brain performance and recovery from muscle injury.

According to the results, older blood significantly inhibits a young mouse’s development.

Young blood can help muscles heal, but isn’t quite enough to reverse cognitive issues associated with ageing.

“Our study suggests that young blood by itself will not work as effective medicine,” Conboy says.

“It’s more accurate to say that there are inhibitors in old blood that we need to target to reverse ageing.”

The effects of old blood on young mice were more significant than any benefits shown from young blood.

“The positive effects of young blood benefit old muscle regeneration, while negative effects of old blood dominate in the young brain,” the researchers write, as old blood stopped new brain cells forming and liver cell regeneration in young mice.

On the plus side, the newly developed method offers a way to test blood exchange more precisely in the lab, which could eventually help fight age-related deficiencies in humans.

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