Easter Island dirt may hold key to longer life

A group of US scientists believe that an anti-fungal agent found in the soil of Easter Island may have life-extending properties.

When the compound rapamycin was fed to middle-aged mice, life expectancy is claimed to have been raised by 28 per cent in males and 38 per cent in females.

The findings published in the journal Nature has the researchers going so far as to say the compound could lead to an "anti-aging pill" for humans.

They caution, however, that using the the drug now to extend lifespan is dangerous because it also strongly suppresses the immune system. Rapamycin is currently used to prevent rejection in organ transplants.

The hope is that further testing of the effects of rapamycin could lead to a safer drug for a human population.

Three research teams - from the University of Texas Health Science Center in San Antonio, the University of Michigan in Ann Arbor, and the Jackson Laboratory in Bar Harbor Maine - chose rapamycin because it appears to shut down the same molecular pathway as calorie restricting, making it a candidate for anti-aging therapy in mammals.

"I've been in aging research for 35 years and there have been many so-called 'anti-aging' interventions over those years that were never successful," said Arlan Richardson, director of the Barshop Institute at the UT Health Science Center. "I never thought we would find an anti-aging pill for people within my lifetime; however, rapamycin shows a great deal of promise to do just that."

Male and female mice were crossbred from four different strains of mice to better simulate the genetic diversity and disease susceptibility of humans. The original idea was to test rapamycin on much younger mice, but the compound first needed some re-tuning to more reliably enter the bloodstream.

By the time they had the compound properly reformulated, the mice were about 20 months old — an age equivalent to 60 in humans. They decided to start feeding it to the mice anyway.

"I did not think that it would work because the mice were too old when the treatment was started," said Richardson. "Most reports indicate that calorie restriction doesn't work when implemented in older animals. The fact that rapamycin increases lifespan in relatively old mice was totally unexpected."

Rapamycin was first discovered as a product of a bacteria found in a soil sample from Easter Island — also known by its Polynesian name Rapa Nui.

Randy Strong, who directs the UT's Aging Intervention Testing Center, said the study of rapamycin has identified it as a potential target for developing drugs for preventing age-related diseases and extending a healthy lifespan.

"If rapamycin - or drugs like rapamycin - works as envisioned, the potential reduction in overall health cost for the US and the world will be enormous." ®