In the 2012 film Snow White and the Huntsman, the evil queen Ravenna tries to restore her youth by sucking her step-daughter dry. It’s a popular trope in Hollywood. But could the vampires have got it right after all? Could the blood of virgins − or at least young people − really prevent mortality?
A raft of rodent experiments has demonstrated that blood transfusions from a young donor reverse the effects of aging in older recipients over recent years.
Whether it actually makes the animals live longer, however, has yet to be firmly established, though in one 1972 experiment older experimental rats lived four months longer than those in a control group.
The work is so promising that phase one clinical trials to see if the technique − transfusing plasma rather than whole blood − is safe for use in humans have been started in California.The company behind those experiments is called Alkahest, a name borrowed from the Swiss alchemist Paracelsus, who used it to refer to the Philosopher’s Stone, which among other things was believed to be the elixir of life.
Alkahest, founded by Stanford University professors Tony Wyss-Coray and Karoly Nikolich, hopes the technique will lead to a reliable treatment for age-related maladies such as dementia, beginning with tests on Alzheimer’s patients, probably in 2016.
One advantage of the approach is that blood plasma is given to people routinely, so the researchers don’t have to go through all the regulatory hoops required of new drugs.
No one is sure yet which factors within the young donor blood have the rejuvenating effect or how exactly they work.
But various tests have shown that the effects are present in muscles − including the heart, where it reverses thickening of the walls − bones and nerve cells. It promotes repair of spinal injuries and encourages the formation of new olfactory neurons. And all of this seems to be linked to more active stem cells.
“I think it’s rejuvenation,” Professor Wyss-Coray told Nature. “We are restarting the ageing clock.”
The recent research has a long medical pedigree. It began when the French scientist Paul Bert who in 1864 reported that he had cut strips off a pair of rats and then stitched the two animals together, later showing that their circulatory systems were linked.
Bert went on to graft the tip of a rat’s tail under the skin of its back and to create a chimeric monster by uniting a cat and a rat. His work may have inspired H G Wells to write The Island of Dr Moreau.
Surgically linking animals became known as parabiosis, and was used in aging researchas early as 1956, though the results were disappointing.
But by the 1970s, despite having helped with discoveries in endocrinology and immunology, the practice died out. No one knows why, but it might have had to do with the rise of ethical concerns about the treatment of laboratory animals.
The technique came storming back in a 2005 paper from a team at Professor Thomas Rando’s neurology lab at Stanford that answered one of the most perplexing questions faced by researchers into longevity: Why do all the tissues in a body age at roughly the same rate?
Their experiment worked better than expected. Stem cells in the older mice started to divide again, restoring muscle, liver and even brain cells.
Something from the young donor blood was making the stem cells behave as if they too were young again.
Several factors have been suggested as candidates, among them oxytocin, better known for its role in emotional bonding, and growth differentiation factor 11.
There are some caveats about the technique. One is the fear that re-activating stem cells, because it results in more cell divisions, could create a cancer risk