Young Blood Can Reverse Aging Process Researchers find the fountain of youth—in blood? By Neal Colgrass, Newser Staff Posted May 4, 2014 5:10 PM CDT 49 comments Comments (Shutterstock) (Newser) – Who knew blood-sucking vampires were actually onto something? According to new US studies, the blood of young mice can rejuvenate the brains and muscles of older mice, effectively reversing the impact of aging, the New York Times reports. "I am extremely excited," says a professor. "These findings could be a game changer." The studies continued an old line of research by stitching younger mice to older ones, enabling them to exchange blood. In time, the young blood boosted activity in older stem cells, which produced new muscle tissue and neurons more easily than before, the Washington Post reports. Other researchers simply injected blood or injected a protein in young blood called GDF11 and also saw positive results. But can all this benefit an aging society and increase human longevity? We won't know until it's tested on people; one researcher says he plans human studies later this year, and hopes to treat Alzheimer's. Now, the caveats: Rejuvenating old body parts could actually increase incidence of cancer if stem cells multiply uncontrollably, a professor warns, and Science notes that none of the treated mice have actually lived longer. Then, there's the creepiness of swapping blood: "It sounds terribly, terribly weird, I have to say," says one expert. "But it's a good way to go."