Ageing can be reversed by adopting an approach used by stem cell scientists to turn back the cellular clock, new research suggests.
In laboratory experiments, researchers rejuvenated human skin, increased the lifespan of mice with a premature ageing disease by 30 per cent and accelerated healing.
Although the work is at a very early stage, they believe it could open the door to “fountain of youth” anti-ageing treatments that would help us live longer and look younger.
The research developed from techniques used to create stem cells with embryonic properties from reprogrammed adult cells.
A key part of the process of producing such "induced pluripotent" stem (iPS) cells involves the re-activation of four dormant genes known as "Yamanaka factors", named after Japanese stem cell pioneer Shinya Yamanaka.
In the new study, scientists activated the genes intermittently and found they were able to turn back the ageing clock without cells losing their adult identity.
Dr Pradeep Reddy, from the Salk Institute in California, said: "In other studies, scientists have completely reprogrammed cells all the way back to a stem cell-like state.
“But we show, for the first time, that by expressing these factors for a short duration, you can maintain the cell’s identity while reversing age-associated hallmarks.”
The genes have to be handled with care because the rapid cell division seen in embryos could be a hallmark of cancer in adults.
Having large numbers of cells revert to an embryonic state in an adult also raises the risk of organ failure and death.
But mice with the premature ageing disease progeria did not develop cancer and appeared to thrive after receiving the treatment.
Compared with untreated mice, they looked younger, the performance of their hearts and other organs improved, and they lived 30 per cent longer.
In normal ageing mice, the intermittent activation of Yamanaka factors led to improvements in the regenerative capacity of pancreatic tissue and muscle.
Injured pancreas organs and muscle also healed faster in otherwise healthy ageing mice that were reprogrammed.
Rejuvenation
Prof Juan Carlos Izpisua Belmonte, who led the Salk team, said: "Obviously, mice are not humans and we know it will be much more complex to rejuvenate a person.
“But this study shows that ageing is a very dynamic and plastic process, and therefore will be more amenable to therapeutic interventions than what we previously thought.”
In the experiments, the mice were treated by spiking their drinking water with a chemical, doxycycline, that activated the four genes.
Continuous activation of the genes resulted in significant weight loss and death after four days, said the researchers, writing in the journal Cell.
This was avoided by switching to a cyclic regime consisting of two days of doxycycline treatment, followed by five days of withdrawal.
PA