A new drug has increased the life of laboratory mice by up to 25%, according to a study.
Researchers say the findings raise the "tantalising" prospect that the drugs could have a similar effect in elderly humans.
They hope the findings could one day potentially extend healthy ageing in people by reducing frailty and the signs of ageing.
The mice that were given the treatment lived for an average of 155 weeks, compared with 120 weeks in untreated mice.
Researchers found that the treatment largely reduced deaths from cancer in the animals, as well as reducing the many diseases caused by chronic inflammation and poor metabolism, which are hallmarks of ageing.
Essentially, the animals lived healthier lives for longer, and according to the findings, there were very few side effects.
Scientists at the Medical Research Council Laboratory of Medical Science and Imperial College London found that switching off a protein called IL-11 increased the healthy lifespan of mice.
In humans, levels of this protein increase as people age, and past research has linked it to a number of conditions associated with ageing, including chronic inflammation, disorders of metabolism, muscle wasting and frailty.
Professor Stuart Cook, who was co-corresponding author, from the Medical Research Council Laboratory of Medical Science (MRC LMS), Imperial College London and Duke-NUS Medical School in Singapore, said: "These findings are very exciting.
"The treated mice had fewer cancers, and were free from the usual signs of ageing and frailty, but we also saw reduced muscle wasting and improvement in muscle strength.
"In other words, the old mice receiving anti-IL-11 were healthier."
He added: "Previously proposed life-extending drugs and treatments have either had poor side-effect profiles, or don't work in both sexes, or could extend life, but not healthy life, however, this does not appear to be the case for IL-11.
"While these findings are only in mice, it raises the tantalising possibility that the drugs could have a similar effect in elderly humans.
"Anti-IL-11 treatments are currently in human clinical trials for other conditions, potentially providing exciting opportunities to study its effects in ageing humans in the future."
The scientists tested the effects of the protein by creating mice that had the gene producing IL-11 (interleukin 11) deleted.
This extended the lives of the animals by more than 20% on average.
They also treated 75-week-old mice - equivalent to the age of about 55 years in humans - with an injection of an anti-IL-11 antibody, a drug which stops the effects of the IL-11 in the body.
According to the findings published in Nature, the mice given the drug from 75 weeks of age until death had their average lifespan increase by 22.4% in males and 25% in females.
Assistant Professor Anissa Widjaja, who was co-corresponding author, from Duke-NUS Medical School, Singapore, said: "Although our work was done in mice, we hope that these findings will be highly relevant to human health, given that we have seen similar effects in studies of human cells and tissues.
"This research is an important step toward better understanding ageing and we have demonstrated, in mice, a therapy that could potentially extend healthy ageing, by reducing frailty and the physiological manifestations of ageing."
The effects of IL-11 inhibition in humans remain to be seen, but early-stage clinical trials are underway to understand the effects of this treatment in patients with fibrotic lung disease.
