Wednesday, July 8, 2009
Rapamycin: "Fountain of Youth Drug?"
"A miraculous 'elixir of youth' which could extend the human life span by more than a decade is being developed by scientists. The anti-ageing pill was created from a chemical found in the soil of Easter Island - one of the most remote and mysterious places on the planet. In tests on animals, the chemical increased life expectancy by a staggering 38 per cent.
While the breakthrough sounds like something out of science fiction, scientists say the discovery is a major leap towards longer lives for everyone. The drug, rapamycin, is already used to suppress the immune systems of organ transplant patients. It is also employed in heart operations and is being tested for its anti-cancer properties. The scientists believe that the drug could be developed within a decade.
Dr Arlan Richardson, who led the research at the University of Texas, said: 'I never thought we would find an anti -ageing pill for people in my lifetime. However, rapamycin shows a great deal of promise to do just that.' An anti-ageing pill is a Holy Grail for medical research and its development would have major repercussions for society.
In a world where people routinely live to 90 and 100, retirement ages would need to creep forward into the 70s while extended life spans would put enormous pressures on healthcare, housing and social services - as well as marriages. The implications of a such a pill also depends on the quality of those extra years. If an ageing drug delays every aspect of getting old, then users could enjoy 100 years of good health. But if it simply postpones death, they could find their last few decades blighted by failing eyesight, hearing loss, frailty and dementia.
Rapamycin was discovered in the 1970s during a worldwide search for new antibiotics. The chemical is produced by a microbe that lives in the Easter Island soil. In its current form, the drug is too dangerous to hand out as an anti-ageing pill. The compound suppresses the immune system and makes patients vulnerable to any viruses and bacteria. The existing version of the drug also increases the risk of cancer and would need to be modified before using in human trials. However, researchers believe the new discovery will lead them to similar - but less harmful - anti-therapies.
In the study, reported today in the journal Nature, scientists tested rapamycin on nearly 2,000 laboratory mice aged around 600 days - roughly the equivalent to a 60-year-old person. Around a quarter of the mice were given a normal diet, the others the Easter Island chemical. The drug increased the maximum life span of the mice from 1,094 days to 1,245 days for females, and from 1,078 to 1,179 days for males. From the point the mice began the treatment, the drug extended the females' life expectancy by 38 per cent, and males by 28 per cent. Overall it expanded their life span by 9 to 14 per cent.
What amazed the scientists is that the drug worked even though the mice started to be given it only in middle and old age. Until now, scientists have developed just two ways of extending the life span of mammals. One is to tinker with their genes, the other to restrict their diet. Repeated studies have shown that cutting calories can make animals and people live longer. Experts believe that rapamycin - which acts on a protein in cells called TOR - might fool the body into thinking that calories are being restricted. British scientists described the findings as exciting - but stressed that rapamycin weakens the immune system, exposing patients to potentially dangerous diseases.
In its current form, an extended life span would come at the cost of having to live in a germ-free tent. Researchers want to find another more subtle drug target that extends life, but which does not damage the immune system. Dr Lynne Cox, researcher in ageing at Oxford University, said: 'In no way should anyone consider using this particular drug to try to extend their own life span as rapamycin suppresses immunity. While the lab mice were protected from infection, that's simply impossible in the human population. 'What the study does is to highlight an important molecular pathway that new, more specific drugs might be designed to work on. 'Whether it's a sensible thing to try to increase life span this way is another matter: Perhaps increasing health span rather than overall life span might be a better goal.'"