Uncovering how the body ages is leading to drugs to reverse it

IN 2016 AFDA startup in California called Ambrosia began offering its customers transfusions of blood from the young. At $8,000 per litre, it was a service for the wealthy who believed that young blood could slow down or reverse the ageing process, thereby reducing their chances of developing cancers, Alzheimer’s disease and heart disease.Earlier this year America’s Food and Drug Administration () cautioned potential customers that there was no proven scientific benefit to receiving such blood. In response, Ambrosia shut down its clinics. But ill-fated startups aside, there is a kernel of truth to the idea that young blood can be rejuvenating. Experiments in the early 2000s in which mice of different ages had been stitched together to share their circulatory systems, known as heterochronic parabiosis, had demonstrated dramatic improvements in the cognition, muscle repair and liver function of the elderly partners. The race this work sparked to translate the idea into something useful to humans, however, raises issues, not least in the squeamishness and hazards associated with sharing blood.