Two studies published on Sunday show that blood from young mice reversed aging in old mice, rejuvenating both their muscles and their brains, The New York Times reports.
Dr. Saul Villeda at the University of California, San Francisco, and his colleagues discovered that after young mice and old mice were stitched together at their flanks and their blood was flowing through each other, the old mice formed several new neurons in the hippocampus region of the brain, an important area for imprinting memories. The scientists also removed cells and platelets from the blood of young mice and injected the remaining plasma into old mice, which helped the older rodents perform better on memory tests.
Over at Harvard University, Dr. Amy J. Wagers and her team found that when old mice were joined together with young mice, more blood vessels grew in the brain of the old mice, leading to the creation of more neurons that gave the old mice a better sense of smell. During an earlier study, Wagers and her colleagues had discovered that GDF11, a protein, was plentiful in young mice and scarce in old mice, and could rejuvenate heart tissue when injected into older mice.
This time around, Wagers and her colleagues injected GDF11 into the old mice (not joined to younger mice) and found that it also spurred the growth of blood vessels and neurons in the brain, as well as — in a separate new study — stem cells in the aging muscles, increasing the strength and endurance of older mice.
Taken together, the separate research could eventually lead to treatments for human heart disease and degenerative brain disorders like Alzheimer's, among other Fountain of Youth remedies. "There's no conflict between the groups, which is heartening," Dr. Richard M. Ransohoff, director of the Neuroinflammation Research Center at the Cleveland Clinic, told The New York Times.
The idea of being able to rejuvenate body parts this way is exciting, but scientists also warn that stem cells could multiply uncontrollably, leading to cancer. Villeda's team published its findings in the journal Nature Medicine, while Wagers' studies came out in Science.