LYONS: Every day our life expectancy rises by six hours, and babies born today are expected to live to at least 100 years on average, experts have reported, with hopes to gain clues about rejuvenation from organisms that are naturally resistant to aging and dying.
Continuously rising life expectancy has come as surprise: the UN had predicted that by the 1980s, we would hit a ceiling, but our maximum life expectancy has not yet been reached, and no-one knows when a maximum will be reached, if ever.
“Increasing life expectancy is probably the biggest threat facing humanity around the globe, bigger even than climate change,” said Thomas Kirkwood, professor at the Institute for Ageing Health at Newcastle University, UK, at Biovision, the 7th World Life Sciences Forum in Lyon, France.
Investing in repair and maintenance
But François Taddei, research director of the Evolutionary Systems Biology team at the French National Institute of Health and Medical Research (INSERM), said that “rising life expectancy is good news”, although we do not know yet why this is happening or whether it will be continuing, as genes and environment only partly explain ageing.
“There is something we’re missing and we have to understand,” said Taddei.
Taddei’s research is based on ‘retirement homes for bacteria’ which use tiny nano-chambers to separate individual bacteria from their offspring, found that even common bacteria like Escheriria coli age and die.
“Each nano-chamber is a private room for a bacterium, with a surveillance camera - it’s like Big Brother,” he said. His research showed that bacteria accumulated cellular damage and that those that invested more in repair and maintenance lived longer.
Watching organisms be \'resurrected\'
But not everyone is happy to sit and wait for the world to become populated with older people. Miroslav Radman, a professor of cell biology at the Medical School of Rene Descartes University in Paris said that as we advance in our understanding of what causes aging, “rejuvenation should become possible”.
Radman presented some of his group’s findings on research on organisms that are naturally extremely resistant to aging and dying. Bdelloid rotifers are small invertebrates that are highly resistant to desiccation and radiation.
They can be taken out of their natural marine environments and “dropped into dust” for years, then \'resurrected\' when immersed in water again, Radman said. They can also survived without sex for some 80 million years.
Reverting back to youth, not death
Similar things happen with the bacteria Deinococcous radiodurans and the jellyfish Turritopsis nutricula that “oscillates between juvenile and ‘menopause’ stage, which makes it practically immortal”, according to Radman.
When it reaches the post-reproductive stage of life, instead of continuing towards death it reverts back to youth.
“These are the extremes of nature that can tell us interesting stories that we could not learn from normal cases ... it’s like literature where crimes and other unusual events tells us about life,” he said.
Understanding the origin of ageing
So how do these organisms to re-assemble their damaged and decayed genomes after years of apparent death? Radman admitted that his team does not yet have the exact answer, but added that there is clearly a cocktail of small molecules acting as an “umbrella against radiation”.
The organisms that they study invest resources into making this cocktail that can soak up free radicals caused by radiation and oxygenation, leaving the functional proteins undamaged.
So even though the DNA gets damaged, the proteins that act as ‘working units’ in the cell are protected: when the opportunity arises, these proteins spring back into action, fixing the DNA and bringing the cell back to life.
“So the origin of ageing could be very simple,” said Radman, who compared it to the rusting of old car parts that need to be replaced. ‘Rusting’ takes place because our bodies don’t invest enough in prevention– the special molecules that protect the DNA of some of simple organisms are lacking in humans.
The anti-ageing cocktail
Radman’s team is now hunting for this cocktail of molecules and when they identify it he plans to test it in mice and then on himself. If it works we could be preventing ageing even before we fully understand how it works, he concluded.
Kirkwood agreed with Radman that evidence seems to indicate that ageing happens because cells do not invest enough energy in maintenance. But as organisms have only a limited amount of energy, trade-offs are an essential part of life.
In order to reproduce, some energy is diverted away from maintenance and repair systems of cells, and this leads to ageing. But Kirkwood said that proteins are only one part of this anti-ageing cocktail.
The changing face of an ageing society
Radman added that the problem is too complicated to tackle with traditional approaches to research: the only way to understand why we age and how ageing contributes to disease development is to employ new systems biology technologies.
Meanwhile, societies will have to adapt to a growing number of elderly people, said other experts at the conference. We will need to reconsider the integration of older people in society and ensure that there is disabled access to buildings and public transport, said John Beard, director of Ageing and Life Course at the WHO.
Beard said we should not be surprised if people soon start changing careers at age 40, as they know they have another 40 years to go: as our life expectancy goes up, people will want to change their life plan, and might not want to retire at 62.