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They did this by creating genetically-modified mice with a defective gene that can be switched off so that their cells ceased to age when a cream was applied to the skin.
While still years from being determined safe for use in humans, the discovery offers hope of one day reversing many age-related illnesses and injuries as the technique may work on any kind of organ or tissue.
"Previous work has shown you can reverse ageing by really drastic measures" such as a near-starvation diet or "connecting the circulation of a young animal to an old animal", said lead researcher Howard Chang of the Stanford University School of Medicine in California.
"Here we show that ageing in mouse skin can be reversed by blocking a single gene," he said.
Ageing also genetic
"These findings suggest that ageing is not just a result of wear and
tear, but is also the consequence of a continually active genetic
programme that might be blocked for improving human health."
Chang's team use a complex computer analysis to discover that a single protein is the "shared driving force for the genetic changing associated with ageing in lots of different tissues," he said in a telephonic interview.
They then designed a genetically-modified mouse in which this gene would switch off only when the animal was quite old.
"We even engineered it in such a way that we can actually turn off that defective version in some parts of the animal and not the rest," he explained.
"We made this animal in such a way that it would respond to a cream that contained a specific chemical and we put the cream only on one half of the animal ... so the rest of the animal was still old."
Two weeks later, both the gene expression profile and the tissue characteristics of the treated skin had reverted to that of a young mouse.
Gene linked to immune system
While the idea of taking a full-body dip in the fountain of youth
might sound like a fantastic idea, there are good reasons to target
only specific areas of the body for treatment.
The same gene that stimulates ageing, NF-eB, is also involved in the immune system and other cell functions, so if it were blocked in the entire body, it could cause death, Chang warned.
The next step is to see if blocking the gene will also reverse ageing in other tissues such as the heart and lungs.
There is also the question of whether the effect will last if the treatment is continued or if the tissues will rapidly revert back to their previous aged state if the treatment is stopped.
Other researchers are already looking at ways to block the gene in humans, using drugs because of its role in the immune system, Chang said.
Might be used for anti-ageing
Further experiments will show whether one of those drugs can effectively
be used to block the gene in targeted ways for anti-ageing purposes.
"What I hope won't happen is a lot of people calling me up to make an appointment to have their face rejuvenated," Chang added.
Even if researchers are able to develop a safe way to use the treatment on humans, there will always be serious risks involved in genetic intervention.
"A lot of people in the field shy away from the fountain of youth and rejuvenation and focus on extracting quality of life," he said. – (Mira Oberman/Sapa/AFP)
Source: Genes and Development.
Read more:
Genes for cancer, ageing?
Long life can be in the genes
November 2007
