Forget antiwrinkle creams. A trio of studies suggests that future age-reversal treatments derived from the blood of youngsters might rejuvenate the body from the inside rather than the outside. Research teams led by Lee L. Rubin and by Amy J. Wagers of Harvard University and by Tony Wyss-Coray of Stanford University connected the circulatory systems of young and old mice so that the animals shared the same blood. Weeks after the procedure, the Stanford team’s elderly mice had sprouted new connections among the neurons in an area of their brains associated with memory (Nat. Med. 2014, DOI: 10.1038/nm.3569). The aged mice in Harvard’s surgically joined pairs grew new blood vessels and neurons in their brains and had an improved sense of smell (Science 2014, DOI: 10.1126/science.1251141). In a separate experiment, when the Stanford researchers periodically injected blood plasma from young mice into old mice, the elderly rodents began to perform better at certain memory tasks. The Harvard scientists zeroed in on one protein in the youngsters’ blood called growth differentiation factor 11 that plays a role in the observed phenomena. Daily doses of the growth factor given to the elderly mice spurred blood vessel growth in their brains and revived their skeletal muscles (Science 2014, DOI: 10.1126/science.1251152).