Blood from young mice prolongs life in old ones

A team of scientists has extended the lives of old mice by connecting their blood vessels to young mice. The infusions of youthful blood caused the older animals to live 6 to 9 percent longer, the study found, roughly equivalent to six extra years for an average human. From a report: Although the study does not point to an anti-aging treatment for humans, it does suggest that the blood of young mice contains compounds that promote longevity, the researchers said. “I would guess it’s a useful cocktail,” said James White, a cell biologist at Duke University School of Medicine and author of the new study.

Linking animals together, known as parabiosis, has a long history in science. In the 19th century, French scientists connected the blood vessels of two rats. To prove that the rats shared a circulatory system, they injected belladonna, a compound from the deadly nightshade plant, into one of the animals. The pupils of both rats dilated. In the 1950s, Clive McCay of Cornell University and his colleagues used parabiosis to explore aging. They joined young and old rats and sewed their flanks together so that the capillaries in their skin fused together. Later, Dr. McCay and his colleagues looked at the cartilage in the old rats and concluded that it looked younger. In the early 2000s, parabiosis had a renaissance. Scientists used 21st century techniques to study what happened when animals of different ages shared the same bloodstream. They found that the muscles and brains of old mice were rejuvenated, while younger mice showed signs of accelerated aging.