The search for medications that extend the lifespan of humans has been going on for many lifetimes. Explorers searched for the legendary fountain of youth said to make anyone who drank from it young again. Today researchers study different medications to extend the lifespan of humans.
Researchers have discovered the first drug that has been proven to extend the lifespan of mammals when taken late in life. The drug is called rapamycin and is derived from bacteria that lives in the soil on the remote and legendary Easter Island most well-known for its gigantic moai statues.
Rapamycin is already used to treat disease in humans and is an antifungal compound that is approved by the FDA as an immunosuppressive therapy to prevent rejection in organ transplant patients. The drug is also undergoing clinical trials at this time as an anti-cancer drug. Previous studies had proven that the drug was capable of extending the lifespan of invertebrates.
The new study gave the drug to mice starting at 20 months of age, the equivalent of 60 human years. During the study, the researchers found that the drug was able to extend the life of male mice by 9% and by 13% in female mice.
David Sinclair, co-director of the Paul F. Glenn Laboratories for the Biological Mechanisms of Aging at Harvard Medical School, said, "Maybe 20 years from now we'll look back at this study as a landmark that pointed the way to medicines of the future." Sinclair was not a participant in the study.
Sinclair continued saying, "It's particularly exciting because it works so late in life to extend life span. The fact that you can give a drug after 20 months of age in a mouse and still see a life-span extension is striking."
The significance is that should the drug move forward in human testing and be approved for use, patients could start taking the medication later in life rather than having to start treatment with the drug earlier in life and be exposed to more side effects.
The results of the study were pooled from the results of three other independent studies conducted at Jackson Laboratory, in Bar Harbor, ME; the University of Texas Health Science Center, in San Antonio; and the University of Michigan, in Ann Arbor.
The researchers point out that finding the efficacy of the drug in extending life span late in life was an accident. The drug was planned to be administered to the mice at four months of age, but the effective dose for treatment was prohibitively expensive. The researchers lost time while they devised a fix for the dosing issue, which was a coating that let the drug be absorbed in the intestine.
The mechanism of action for the drug remains to be seen say the researchers. Rapamycin is known to act on a protein called target of rapamycin (TOR) which helps cells make new proteins and helps prevent destruction of malfunctioning cells. The effect of the drug to fight aging in humans is unknown say the researchers since the medication has significant side effects like fungal infections and pneumonia because it suppresses the immune system. The researchers hope that further refinement of the treatment could one-day lead to an extra decade or two of "relative good health."