Dolly the cloned sheep did not age prematurely, research finds

DOLLY the sheep did not develop arthritis or age prematurely, scientists say, in research which suggests cloning is safer than previously thought.

The world’s first animal cloned from an adult cell was born in Edinburgh in 1996 and died in 2003 aged six. At the time, scientists believed that genetic problems caused by the cloning process had led Dolly to age more quickly, leading the animal to develop painful osteoarthritis.

But a new radiographic assessment of its skeleton by experts at the universities of Nottingham and Glasgow found it had no more signs of ageing than any other sheep of a similar age. The team also looked at Dolly’s offspring, Bonnie, as well as two other cloned sheep, Megan and Morag, and found that none of them showed any signs of unusual arthritis.

Sandra Corr, professor of small animal orthopaedic surgery at Glasgow University, said: “We found that the prevalence and distribution of radiographic osteoarthritis was similar to that observed in naturally conceived sheep, and our healthy aged cloned sheep. As a result we conclude that the original concerns that cloning had caused early-onset osteoarthritis in Dolly were unfounded.”

Initially Dolly seemed healthy and was successfully mated to produce six lambs naturally. However in late 2001 Dolly began to walk stiffly and was euthanised in February 2003.

At the time, Prof Ian Wilmut, who led the team which cloned Dolly, said there was no way of knowing if the problems were down to cloning or a coincidence. However the Nottingham team decided to look at the skeleton to find out whether Dolly really was suffering from premature arthritis.

They travelled to the National Museum of Scotland in Edinburgh, where Dolly is kept, to scan the animal’s bones and found no evidence of any bone conditions not normally expected of a sheep of the same age.