Blood of Young Mice Extends Life in the Old

A team of scientists has extended the lives of old mice by connecting their blood vessels to young mice. The infusions of youthful blood led 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: While the study does not point to an anti-aging treatment for people, it does hint 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 the Duke University School of Medicine and an author of the new study.

Joining 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, stitching together their flanks so that the capillaries in their skin merged. Later, Dr. McCay and his colleagues examined the cartilage in the old rats and concluded it looked younger. In the early 2000s, parabiosis went through a renaissance. Researchers used 21st century techniques to study what happened when animals of different ages shared the same bloodstream. They found the muscles and brains of old mice were rejuvenated, while younger mice showed signs of accelerated aging.