Wilmut disappointed, others happy with cloning progress

Recent media interviews with Dr Ian Wilmut, the scientist responsible for cloning Dolly the sheep, have suggested that all clones are genetically and physically defective.

But other scientists have disagreed with Wilmut's pessimistic view.

"The technology is still far from perfect," said Australian Ian Lewis, who is developing cattle cloning technology at Genetics Australia, but "it's only been 6 years since Dolly arrived."

According to a story in UK newspaper The Sunday Times on April 28, Wilmut said that problems such as excessive size, obesity, developmental difficulties and other problems occurred regularly in cloned animals.

"The widespread problems associated with clones has led to questions as to whether any clone was entirely normal," the paper quoted Wilmut as saying.

In an earlier story in The Guardian newspaper, Wilmut cited the high rate of failure in cloning experiments, saying that he had thought that more progress would have been made by now.

In a letter to The Guardian in response to the story, Alan Colman, formerly of PPL Therapeutics and now with Australian company ES Cell, argued that Dolly's ailments "should not be used to condemn promising new developments".

"She has never been a normal sheep, more a pampered, overweight media hog," Colman wrote. "She does have hip arthritis and is middle-aged. I have hip arthritis and am middle-aged. I am not a clone."

Lewis said he disagreed with Wilmut's view that all cloned animals were defective.

"Worldwide there are well over 200 cloned cattle, apparently healthy and normal," he said. "There have been fairly dramatic improvements in efficiency."

Genetics Australia has two cloned cows, Suzi and Mayzi, who are pregnant, Lewis said, as well as six transgenic cloned calves born earlier this year.

"We do have losses all the way along," Lewis said. "Some animals that are born don't make the grade."

As a vet, Lewis said he was very concerned about such problems and the animals' welfare. He said that even in conventional breeding, problems arose. But that was no reason to stop developing the technology.

"It's really disappointing when you have losses. I try to keep focussed on the longer term goals," Lewis said. "I'm fairly confident that we'll overcome these problems eventually."

Lewis added that advances in the technology were adding to knowledge of cell biology and could have further benefits down the road. He said the main reason for developing these technologies was to improve agriculture and human medicine: "These are all powerful objectives to be working for."