Canadian Press, Dec. 19, 2002
http://www.ctv.ca/
TORONTO — An ordinary looking sheep named Dolly made history in 1997 as the first cloned mammal. Many of the clones that have followed in Dolly’s wake have looked anything but ordinary.
Regardless of what the future holds for the science of cloning, experts say the present does not hold enough information or skill for the process to be used reliably and safely in humans.
“All the people who’ve cloned mice and so on would tell you that right now this is so inefficient and the chances of abnormalities so high that they would not, for safety reasons, propose that human cloning be undertaken – let alone the ethical concerns,” says Janet Rossant, a senior investigator at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital in Toronto.
“I think it’s very unlikely that anyone is going to have success at this on the short term.”
A Quebec-based religious cult known as the Raelians has announced an American woman will give birth within days to a clone of herself. The cult has declared its intention to clone humans in the past, but has never allowed outside investigators to scrutinize the work, nor has it shared results with the rest of the scientific world via medical and scientific journals.
Their latest claim – along with those of two rival and equally secretive groups who insist they are on the verge of the same feat – is greeted with deep skepticism within the scientific world.
That’s because the much trumpeted cloning successes – since Dolly, scientists have cloned mice, cows, pigs, goats and cats – are vastly outnumbered by cloning failures.
The process, called nuclear transfer, works like this: researchers take an egg from a female mammal and a cell containing DNA from a mammal of the same species. The nucleus from the egg is removed and is replaced with the nucleus from the cell. The two are fused using an electrical shock. When the egg begins to divide, it is implanted into the uterus of a host female.
The resulting offspring, if one survives, is a clone of the animal from which the cell was taken.
But more often than not, the process does not work. In fact, it’s been estimated that as many as 97 per cent of cloning attempts fail.
“The reason for this we don’t fully understand but what we know is getting the DNA to get properly reprogrammed – putting it back in the eggs – seems to be harder than we thought,” Rossant says.
Scientists at Texas A & M University announced earlier this year that they had logged another cloning first, a cat. The kitten, aptly named “cc”, was the only live cat produced from 87 cloned embryos that were implanted into eight female cats. That’s in line with other cloning efforts.
“In all cases the efficiency has been very, very low,” says Rossant, who also teaches in the University of Toronto’s department of medical genetics and microbiology.
“That is to say for the starting number of eggs, the resulting number of live births is very, very low. . . . And even when successful, the animals are not usually very normal. Some look relatively normal but many have abnormalities. So this is a real problem.”
Dolly is a good example. Researchers at the Roslin Institute in Scotland, where she was created, revealed this year that she has arthritis. They believe the premature onset of this ailment may be a product of the fact Dolly was cloned.
Experts have speculated that cloned animals might have a shorter lifespan. It is certainly known that premature aging isn’t the only problem clones face.
“Nearly every cloned animal in any species has something called large offspring syndrome. The babies that are born are very big,” Rossant said.
An American researcher reported last year that work on cloned monkey embryos showed a host of problems.
Even embryos that looked healthy were a “gallery of horrors,” Tanja Dominko said when she presented results of the work at a conference in Washington, D.C. Dominko did the work at the Oregon Regional Primate Research Centre.