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Reflections on Dolly the sheep, 20 years on
02:59 - Source: CNN

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On February 22, 1997, the world learned about Dolly the sheep

Scientists have been using insight from Dolly to advance stem cell therapies

CNN  — 

On February 22, 1997, the world learned about a secret project that scientists at the Roslin Institute in Scotland had been working on.

More than seven months earlier, on July 5, 1996, they had aided a Scottish Blackface sheep in giving birth to a Finn Dorset lamb codenamed 6LL3.

She was the first mammal to ever be cloned from the cells of an adult animal.

Using a breakthrough technique called somatic cell nuclear transfer, scientists at Roslin took a nucleus – the part of the cell that contains most of its genetic information – from cells within the mammary gland of an adult sheep and stuck it inside an unfertilized egg from which the nucleus had been removed.

They stimulated the egg to develop into an embryo and planted the embryo into a surrogate mother. The lamb was dubbed Dolly, a nod to country music legend Dolly Parton and her famously ample bosom.

Years later, that same cell cluster was used to make four other sheep just like Dolly.

Revealing Dolly

The lab had kept her birth secret for seven months to make the announcement coincide with the publication of the scientific paper describing the experiments that produced her, they said.

That week, they recall, they received 3,000 phone calls from all over the world, according to the Roslin Institute.

Much of the news reports had focused not on cloning sheep but on its potential for humans, said Alan Colman, who is now a visiting scholar in the Harvard University Department of Stem Cell and Regenerative Biology.

At the time, Colman was research director at PPL Therapeutics, which specialized in producing transgenic (genetically engineered) livestock.

“We’d underestimated the impact the announcement would make,” he said. “It was something we had prepared for, but we had been totally overwhelmed by the response.”

Dolly’s legacy

Previously, cloning had been done using only embryonic cells, and now researchers had showed that it was possible in cells from another part of the body – an adult body.

“At the time she was born, I was ecstatic, because no one had previously been able to use nuclear transfer to make an adult vertebrate from an adult cell,” Colman said.