A protein that can make old blood young has been discovered by scientists, once again sparking hopes of eternal life.
Many have longed for a magic potion to reach triple figures, but until now medical breakthroughs had been scarce.
However, German researchers now claim that they have pinpointed exactly how blood can be kept young - pointing to an array of health benefits. And they are working towards creating a drug containing levels of a protein that they believe could encourage blood to behave more youthfully.
Study author Dr Hartmut Geiger, of the University of Ulm, said: 'If we can translate this into a treatment, we can make old blood young again.'
In a study of the bone marrow of mice, they found older rodents tended to lack levels of osteopontin, New Scientist reports.
They noticed how quickly blood stem cells without the protein aged when they were injected into mice, according to the study published in EMBO journal.
But they also found that when the older stem cells were mixed in with the protein, they began to behave like their younger counterparts. Specifically, they were able to produce white blood cells quicker - an ability known to worsen with older blood.
Both red and white blood cells are made by stem cells that are created by 'mothers' in the bone marrow. Scientists know that these cells often deplete in old age, and this has previously been linked to the world's leading killer.
It comes straight from the pages of a gothic horror novel, but the Dracula-esque transfusion of younger blood has long been linked to health benefits.
So-called 'vampire therapy' can repair muscle tissue, as well as the liver and brain after only 24 hours.
The US scientists found, while young blood does appear to benefit health, it does not improve brain cells used for memory and learning.
A Harvard study has previously found an 'anti-aging' protein, GDF-11, which depletes in the blood as mice age.
This could explain the rejuvenation seen in older animals given young blood, although scientists are still searching for more clues.
However, blood from someone else can be rejected by the body, running the risk of organ failure and casting doubt on whether the mouse experiment would work in people.