Maybe it’s in the blood


The first signs that young blood could blunt the ravages of aging came more than 60 years ago when a team at Cornell University — using a somewhat ghoulish procedure devised a century earlier and used to study wound healing — sutured together two rats so that they would share a common circulatory system. After old and young rats were joined for many months, the bones of both animals became similar in weight, volume and density, thus helping to ward off the bone brittleness that typically accompanies old age.

Some 15 years later, researchers at the University of California performed their own old–young rat pairing experiments. As they reported in 1972, older partners in this arrangement lived around 10 to 20 percent longer than control rats paired to other old animals.

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When Wagers and her colleagues attached the circulatory systems of young mice to old ones, they found strong evidence of a biological reversal of many characteristics of aging. Later, Dr Wagers and colleagues discovered that injecting only GDF11 in aged animals can reproduce many of the benefits of parabiosis.

“What they found is that the old animals exposed to young blood experienced a biological reversal of aging by many different measures. Their brains grow younger, their hearts grow younger, their lungs, their bones – all over their body. And interestingly, the young animals exposed to old blood have accelerated aging. So this is just really strong proof that circulating factors regulate aging,” said Allen.