More cloned puppies born
Hwang's former colleagues improve canine cloning efficiency.
More cloned puppies have been born to the lab formerly associated with South Korean cloner Woo Suk Hwang.
Hwang left his job at Seoul National University this year after an investigation found that he had faked data in papers on cloning human embryos for the derivation of stem cells. Those papers were retracted, and Hwang is facing criminal charges associated with his work. But many of his former colleagues are continuing with cloning research.
One team of researchers at Seoul National University, which only partially overlaps with those named on Hwang's human cloning papers, previously succeeded in producing the world's first cloned dog: Snuppy, an Afghan hound born from an adult skin cell1,2.
Now that same group minus Hwang and with a few other changes to the team has produced three more dog clones, they report in the veterinary journal Theriogenology3. The puppies, named Bona, Peace and Hope, were born this June and July, the team said in a news conference. Like Snuppy, the dogs are also Afghan hounds, but unlike Snuppy they are female.
The achievement confirms that it is just as possible to clone female pups as male ones, notes the team, and shows that the efficiency of canine cloning can be improved.
Fewer eggs, more pups
At the time that Snuppy was announced to the world, researchers were impressed by the technical achievement in cloning a dog a task known to be technically possible but notoriously difficult (see ' Snuppy rewards dogged approach'). If the efficiency of the process could be radically improved and a kennel of cloned dogs produced then it could one day be used to help study models of human disease.
Lead researcher Byeong Chun Lee says that the team has improved the efficiency of the cloning technique. In the current work, the team transplanted 167 cloned embryos into 12 carrier females to produce 3 live pups. Previously, the team transplanted 1,095 cloned embryos into 123 carrier females and produced two pups: Snuppy and another dog that died soon after birth.
A leap in efficiency was similarly claimed between Hwang's two human embryo cloning papers, with the first published in 2004 and the second in 2005.
"Both are huge improvements in a short time frame," says Christopher Scott, executive director of the Program on Stem Cells and Society at the Stanford Center for Biomedical Ethics in Palo Alto, California. He says he will remain unconvinced by the claimed efficiency boost until there is independent confirmation of the technique.
Other scientists say the achievement is plausible, because this is where the team's expertise lies. "They're very good at producing animal clones," said Arthur Kriegstein, director of the Program in Developmental and Stem Cell Biology at the University of California, San Francisco.
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- Lee B. C., et al. Nature, 436 . 641 (2005).
- Parker H. G., et al. Nature, 4440. E1 - E2 (9 March 2006).
- Jang G., et al. Theriogenology, advance online publication . 641 (13 December 2006) doi:10.1016/j.theriogenology.2006.11.006.