Licking big challenge, scientists clone a dog

WASHINGTON — South Korean researchers said yesterday they have created the world's first cloned dog: a playful black, tan and white Afghan hound named Snuppy.

The puppy, grown from a single cell taken from the ear of a 3-year-old male Afghan hound, marks a milestone in the race to fabricate genetically identical dogs for research and as companion animals.

Snuppy — short for Seoul National University Puppy — is the sole survivor among more than 1,000 cloned embryos that were transferred into surrogate mothers.

Cloning experts were impressed that even one healthy dog was created. Even as teams around the world produced cloned mice, rabbits, pigs, cows, cats and one horse, the eccentricities of the canine reproductive system have made it notoriously difficult to add man's best friend to that list.

Companies that plan to offer dog-cloning services were quick to herald the achievement, published today in the journal Nature.

"This validates one of the premises of our business," said Ben Carlson, a spokesman for Genetic Savings & Clone. The Sausalito, Calif., company is storing DNA samples from several hundred dogs in anticipation of producing clones for customers as early as next year.

But some animal-rights activists decried the work as inhumane and wasteful given the glut of unwanted dogs at shelters.

"The cruelty and the body count outweighs any benefit that can be gained from this," said Mary Beth Sweetland, vice president of People for the Ethical Treatment of Animals (PETA) in Norfolk, Va.

The researchers in South Korea emphasized that their goal was not to reproduce beloved pets.

Hwang Woo-suk, one of the lead researchers, said his group's primary aim was to develop genetically identical laboratory dogs for the study of animal and human diseases.

"With the promise of using a homogenous population of cloned dogs, maladies such as hypertension, diabetes, breast cancer or genetic disorders like congenital cardiac defect can be studied more efficiently," said Hwang, whose lab was the first to clone human embryos last year.

Doggy difficulties

Scientists have been trying to clone dogs since shortly after the birth of Dolly the sheep, the first animal cloned from an adult, in 1996.

The technique involves harvesting unfertilized eggs from females, removing the genetic material and replacing it with DNA from a donor, usually taken from a skin cell. The manipulated embryo is then implanted into a surrogate mother.

Even as cloning became routine in many species, dogs remained elusive.

"Probably most important is the difficulty in obtaining good quality eggs," said Dr. Duane Kraemer, a professor of veterinary physiology at Texas A&M University who helped clone the first cat but could not succeed with dogs.

Female dogs come into heat only once or twice a year, providing researchers with relatively few opportunities to extract eggs or implant cloned embryos into surrogate mothers.

Making matters more difficult, eggs harvested from canine ovaries are not mature enough to be coaxed into pregnancy. Research teams have been testing a variety of methods for ripening the eggs in the laboratory, as can be done with eggs from other species, but have yet to hit upon a reliable method.

The South Korean team allowed the eggs to leave the ovaries and mature for a few days in the body before flushing them out.

That turned out to be an important decision, but it also created a different challenge. By then, the eggs had migrated to the oviduct, a thin tube that carries them to the uterus.

Locating an egg in the oviduct — and retrieving it — is considerably more difficult than harvesting eggs from an ovary, said Dr. Betsy Dresser, senior vice president of research for the Audubon Nature Institute in New Orleans, which uses cloning to help preserve endangered species.

In addition to using improved techniques, the South Korean team also benefited from trial and error.

The researchers transferred 1,095 cloned embryos into 123 surrogate dogs to produce three pregnancies, one of which resulted in a miscarriage.

Snuppy was delivered by Caesarean section in late April. A second puppy died of pneumonia 22 days after birth. The researchers do not think the illness was related to cloning.

Snuppy is healthy and lives in the university's research facility, Hwang said.

Gerald Schatten, a biomedical researcher at the University of Pittsburgh and a co-author of the study, said the inefficiency of the process suggests commercial dog cloning for pet owners is a ways off.

"We transferred 1,095 embryos and got one dog," said Schatten, who leads the Pittsburgh Development Center, a biology research institute. "If I were an investor and someone came in and said we have a technique that works at 0.09 percent, I'd say that doesn't sound like a good investment."

Dolly's "dad" speaks out

Pet cloning became a reality in 2002, when scientists at Texas A&M produced a cloned kitten named CC, or Carbon Copy. Genetic Savings & Clone, which funded the research, charges $32,000 for the service.

Though Hwang considers pet cloning frivolous, he said the technology could one day be used to make genetic copies of top-notch guide dogs, search dogs, rescue dogs and other service animals.

Dresser, of the Audubon Nature Institute, said endangered canine species such as the Ethiopian wolf and the Mexican gray wolf could also benefit from cloning.

Ian Wilmut of the University of Edinburgh, who led the effort to clone Dolly the sheep, said in an e-mail that the success in dogs should motivate legislators around the world to enact bans on the creation of cloned babies. "Successful cloning of an increasing number of species confirms the general impression that it would be possible to clone any mammalian species, including humans, given an optimised method," Wilmut wrote.

Hwang's lab has cloned human embryos, but they grew for only five days before being transferred to culture dishes, where they developed into stem cells designed to be used in scientific experiments. "Our research is medical research ... ," Hwang said. "Human reproductive cloning is unsafe, unethical and should be illegal, just as it is illegal in Korea."

Material from the Chicago Tribune is included in this report.