The life of a mouse may not seem especially consequential to you, but it matters to the mouse. And it matters to scientists who are trying to figure out how to extend the lives of mice.
And it probably matters to their funders, who no doubt hope that the longevity studies scientists conduct might one day carry over the genomic divide separating mice from men. But at what cost?
There have been many success stories in efforts to extend the human lifespan in the past 200 years. Initial advances in sanitation, vaccination and the treatment of infections allowed the expected lifespan of a child at birth to rise beyond the average of 35 to 40 that had prevailed until the 1800s.
More recent treatments for coronary disease, diabetes and cancer mean that more people are living into their 80s and beyond.
The extension of life has potentially negative consequences for wider society, however. Wealthy economies in particular face the prospect of a future in which citizens who are too frail to work outnumber those who are economically active. Already, in Japan, there have been more elderly people than children since 1997. In fact, in 2014 more adult diapers were sold there than nappies for babies. How do you like them apples?
But perhaps one day being old won’t mean being frail. Last week a large research team led by Ming Xu, Tamara Tchkonia and James Kirkland of the Mayo Clinic in the United States published research in Nature showing that by giving mice an expensive drug used in the treatment of certain types of leukaemia, as well as a substance extracted from a decidedly (and deciduously) not-expensive apple peel, they could extend their lives by as much as 36%. The mice’s lives, that is, not the scientists’ .
What’s more, when elderly mice were treated they regained vigour and strength, displaying robust behaviour consistent with that of far younger mice.
The study targeted senescent cells, which normally begin to occur in humans in their 60s. These cells are damaged, but do not die and are therefore not replaced by the body. Instead, they produce chemicals that cause inflammation, and contribute to the onset of age-related diseases and conditions ranging from dementia to heart failure.
The researchers first wanted to establish that these cells helped cause the physical dysfunctions associated with age-related frailty in the first place. They transplanted senescent cells into young mice, which quickly began to lose strength, speed and energy.
They then treated these mice with a cocktail of dasatinib — a drug prescribed for certain kinds of leukaemia — and quercetin, a substance found in apple peels. This treatment caused the selective elimination of senescent cells, which in practical terms led to the mice regaining their previous vigour.
After confirming the role of the senescent cells in the reduction of vitality, the Mayo team then treated elderly mice with the same cocktail.
The scientists found a similar rejuvenating effect: the elderly mice did not just live longer, they remained healthy and retained their vigour for longer.
But anyone seeking to extend the life of their own pet mouse by 36%, be warned: it does come at a cost. Specifically, about R730 a day for treatment with dasatinib, according to a January report by Cancer Alliance on the availability of cancer drugs in South Africa.
Apples, meanwhile, start at R1.50.
* Offer valid for mice only; a daily charge of R734.50 may apply