For ages, men have scoured remote and faraway places to find something that could possibly retain youth in old age but it appears that the elixir of youth has been with man all along, in the blood of young animals.

In three new and separate studies, researchers from the Harvard University, University of California San Francisco and Stanford University School of Medicine found that the blood of young mice can help reverse aging in older mice. The researchers used different approaches in their study to test the rejuvenating effects of young blood but eventually found evidence that makes the concept of perennially youthful vampires plausible. 

The first group of researchers from the Harvard University first joined the blood vessels of young and old mice and observed that blood from the young mice rejuvenated the muscles of the older mice. Later, they administered a protein in the blood known as growth differentiation factor 11 or GDF11 into older mice.

GDF11 regulates stem cell activity and is more abundant in the blood of young animals including mice and humans than in the blood of older animals. The researchers observed that the older mice injected with GDF11 grew new blood and brain cells resulting in improved brain function.

Meanwhile, researchers from Harvard working on the second study observed that by boosting the GDF11 in the blood of older mice, the animals were able to run faster as well as exhibited improved ability to recover from injury.

Amy Wagers, professor of stem cell and regenerative biology at Harvard University who was involved in both studies published in the journal Science this week said that the brain and muscle are significantly affected when a person grows old.

"Changes in these tissues are responsible for the changes that people worry about the most -- loss of cognition and loss of independent function," Wagers said.

For the third study published in the journal Nature Medicine May 4, researchers from the University of California San Francisco and Stanford University School of Medicine joined the circulatory systems of pairs of old and young mice by stitching them together and observed that the older mice given repeated infusion of blood from young mice showed improvements in age related memory tasks.

"Our data indicate that exposure of aged mice to young blood late in life is capable of rejuvenating synaptic plasticity and improving cognitive function," reported study researcher Tony Wyss-Coray from Stanford University's Department of Neurology and Neurological Sciences and colleagues.

Even in this modern age, man continued to hunt for the "fountain of youth." Finding what could possible lead to prolonged youth has significant implications particularly in the field of medicine as this could lead to effective treatment and even prevention of age-related health conditions such as Alzheimer's.