The Spanish blood plasma company Grifols will buy the antiaging plasma protein start-up Alkahest for $146 million. Grifols acquired a 45% stake in the firm in 2015. Alkahest was founded by Stanford University neuroscientist Tony Wyss-Coray in 2014 and is based on the discovery that the blood of young rodents improved the health and cognition of old rodents. The firm is seeking differences between young and old plasma that may influence aging. It has small-molecule and protein drug candidates in clinical trials for Alzheimer’s disease, Parkinson’s disease, and other conditions.