Scientists at the Salk Institute in La Jolla, California, have found that intermittent expression of genes normally associated with an embryonic state can reverse the hallmarks of old age.

This approach – which not only prompted human skin cells in a dish to look and behave young again – also resulted in the rejuvenation of mice with a premature ageing disease, countering signs of ageing and increasing the animals’ life spans by 30 per cent.

“Our study shows that ageing may not have to proceed in one single direction,” said Juan Carlos Izpisua Belmonte, a professor in Salk’s Gene Expression Laboratory and senior author of the paper, which appears in the December 15, 2016 issue of Cell. “It has plasticity and, with careful modulation, ageing might be reversed.”

Izpisua Belmonte cautioned that mice are not humans, and that it will be a much more complex undertaking 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.”

The Salk researchers believe that induction of epigenetic changes via chemicals or small molecules may be the most promising approach to achieve rejuvenation in humans. However, they caution that due to the complexity of ageing, these therapies may take up to ten years to reach clinical trials.