'˜Elixir of youth' hope as scientists extend lives of mice

The elixir of youth could be within reach after an extraordinary experiment in which the lifespan of mice was extended by up to 35 per cent.

Researchers managed to extend the lives of mice by 35 per cent. Picture: AFP/Getty

The secret is simply to remove worn-out “senescent” cells that accumulate with age and have a destructive effect on the body, scientists found.

When this was done using a drug to activate a “suicide gene” in genetically modified mice, the effects were dramatic. Treated animals not only lived 25 per cent to 35 per cent longer, but in many respects they were healthier too.

The mice remained more active and their hearts and kidneys functioned better than mice left to age naturally.

Their body tissues and organs also bore less evidence of damaging inflammation, and they grew fewer tumours.

Scientists are still not sure to what extent humans stand to benefit from the discovery. But a number of research groups are already on the hunt for senescent cell-targeting compounds that could form the basis of lucrative treatments.

US scientist Dr Darren Baker, who led the study, said: “It is not a far fetched idea to think that there will be things coming down the pipeline that influence or remove these senescent cells.”

Senescent cells are potentially dangerous defective old cells that are prevented from dividing and enter a state of suspended animation.

But even though they no longer reproduce, they can still do harm by secreting molecules that damage adjacent tissues and trigger chronic inflammation.

For this reason, senescent cells are closely associated with age-related diseases and frailty. Although the immune system sweeps them away on a regular basis, this process becomes less effective with time and they are allowed to accumulate.

The Mayo Clinic team wanted to see what would happen if middle-aged mice were protected against the effects of senescent cells.

A strain of transgenic mouse was created with a “suicide gene” that targeted and killed off senescent cells when activated by a particular drug.

Even though senescent cells only made up a small fraction of the animals’ total cell population, their removal had far-reaching effects.

The treatment had no obvious negative side effects

Since the research technique relied on genetic engineering it could not directly be applied to humans, said Dr Baker. But he knew of “a variety of groups” that were trying to track down compounds which selectively wiped out senescent cells.