GM mice may unlock anti-ageing secret

Seattle:Genetically modified mice that live 20 per cent longer than normal have been created by scientists in an experiment that opens approaches to extending the human lifespan.

The new strain of mouse produces more of an antioxidant protein that limits tissue damage caused by highly reactive chemicals called free radicals, which could also be exploited to fight the ageing process in people.

The US research suggests that drugs that protect the body against free-radical damage could cure age-related conditions such as heart disease and help people to live substantially longer.

It also indicates that stimulating the body’s own production of antioxidants is likely to be more effective than using drugs, vitamins or other supplements with similar properties.

The benefits of catalase, a natural antioxidant enzyme, were seen only in mice that made extra quantities in specialised parts of their cells. This suggests that increased production needs to be targeted precisely for maximum effect.

Peter Rabinovitch, Professor of Pathology at the University of Washington School of Medicine in Seattle, who led the research, said that removing free radicals at the source appeared to be the most promising way forward for anti-ageing medicine.

“This study is very supportive of the free-radical theory of ageing,” Professor Rabinovitch said. “It shows the significance of free radicals, and of reactive oxygen species in particular, in the ageing process.

“People used to only focus on specific age-related diseases, because it was believed that the ageing process itself could not be affected. What we’re realising now is that by intervening in the underlying ageing process, we may be able to produce very significant increases in ‘healthspan’, or healthy lifespan.”

Previous research has revealed two methods that can extend the lifespan of mice, but neither of these appears to be practical for human use. Mice that are fed diets that border on starvation rations live substantially longer, as do rodents that lack a genetic growth factor.

The first approach is not suitable for people because it would be virtually impossible to follow for long periods, and the second has the side-effect of provoking dwarfism.

As a result, research into ageing has increasingly focused on the activity of free radicals and antioxidants, which are widely thought to play a critical part in the tissue damage that accumulates as organisms age.

In the new study, details of which are published today in the journal Science, Professor Rabinovitch’s team sought to analyse the effects of catalase, an enzyme made by cells that helps to convert hydrogen peroxide into water and oxygen. Hydrogen peroxide is a waste product of metabolism that is often the precursor of free radicals, particularly reactive forms of oxygen, that can damage cells. This cellular damage itself leads to the production of more free radicals, creating a vicious circle of age-related decline.