The prospect of holding back the years with a simple injection could be closer than we think.
Scientists have taken a step towards developing a treatment that could erase the health problems associated with ageing.
While their breakthrough relates to rogue genes behind two rare genetic diseases, the approach they used could one day be harnessed to slow down the ageing process - creating an "elixir of life".
The research focuses on mitochondria, sausage-shaped "powerhouses" in every cell of the body except red blood cells.
They turn the food we eat into energy that can be used by the heart, muscles, brain and other parts of the body.
Research has suggested their deterioration is an important cause of ageing, according to a report in New Scientist magazine.
Defects in this mitochondrial DNA are blamed for a range of rare genetic diseases, including some forms of diabetes, blindness and heart problems.
They have also been linked to ageing - suggesting that fixing the flaws could slow down the onset of old age.
However, all attempts to fix flaws by inserting healthy DNA into mitochondria - a technique known as gene therapy - have failed, with the fresh genes stubbornly staying outside the powerhouses.
Now, by labelling the functional genes with an "address code" - which effectively tells them where to go - French scientists have succeeded in smuggling them inside the mitochondria.
Once there, the pair of genes repaired the damage behind a rare form of blindness and a muscle wasting disease, says the New Scientist report.
In time, the same approach could be used to create injections of genes that will erase flaws thought to be linked to the ageing process.