“Our study shows that ageing may not have to proceed in one single direction,” said Dr Juan Carlos Izpisua Belmonte, a professor in Salk’s Gene Expression Laboratory. “With careful modulation, aging might be reversed.”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 future people could take a pill which turns their cells back to a much younger start, avoiding the need for cosmetic surgery Credit:Maggie West “In other studies scientists have completely reprogrammed cells all the way back to a stem-cell-like state,” says co-first author Pradeep Reddy, also a Salk research associate.”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 breakthrough could also help people stay healthier for longer. The ageing population means that the risk of developing age-related diseases, such as dementia, cancer and heart disease also rises. But if the body could be kept younger for longer then it could prevent many deadly diseases for decades. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. An end to grey hair and crows-feet could be just 10 years away after scientists showed it is possible to reverse ageing in animals.Using a new technique which takes adult cells back to their embryonic form, US researchers at the Salk Institute in California, showed it was possible to reverse ageing in mice, allowing the animals to not only look younger, but live for 30 per cent longer.The technique involves stimulating four genes which are particularly active during development in the womb. It was also found to work to turn the clock back on human skin cells in the lab, making them look and behave younger.Scientists hope to eventually create a drug which can mimic the effect of the found genes which could be taken to slow down, and even reverse the ageing process. They say it will take around 10 years to get to human trials. Scientists have known for some time that the four genes, which are known collectively as the Yamanaka factors, could turn adult cells back to their stem cell state, where they can grow into any part of the body. Mice that had a premature ageing disease returned to a healthy state Ageing is a plastic process and more amenable to therapeutic interventions than we previously thoughtDr Juan Carlos Izpisua Belmonte, Salk Institute But it was always feared that allowing that to happen could damage organs made from the cells, and even trigger cancer.However, it was discovered that stimulating the genes intermittently reversed ageing, without causing any damaging side effects.In mice with a premature ageing disease, the treatment countered signs of ageing and increased their lifespan by 30 per cent. If it worked similarly in humans it could allow people to live until more than 100 years old. In healthy mice it also helped damaged organs to heal faster.