The quest to duplicate a dog been something of a Holy Grail in the tricky field of mammalian cloning. Since Dolly the sheep was cloned in 1996, scientists have followed with pigs, cattle, mice, rabbits, horses and cats. But though they tried mightily, nobody had ever created a genetic double of man's best friend. Not, that is, until South Korean researcher Woo Suk Hwang and his team at Seoul National University brought Snuppy the puppy into the world--an animal whose entire genome came from a single cell from the ear of a three-year-old Afghan hound. Snuppy's arrival, announced in Nature last week, earned grudging admiration from rival cloners in the U.S.
It also raised two big questions. The first, from many a dog owner: When can I clone my dog? The second: What are they going to clone next? The answer to the first is not very soon. The Korean achievement proves that cloning a dog is possible, not that it's easy. Indeed, billionaire John Sperling, who co-founded the cleverly named Genetic Savings & Clone (GS&C), of Sausalito, Calif., has spent seven years and more than $19 million trying in vain to clone a dog. Texas A&M researcher Mark Westhusin, whose team cloned a cat on its second try in 2001, abandoned the dog-cloning project several years ago. When the company approached reproductive physiologist George Seidel Jr. of Colorado State, he wouldn't even try.
One problem with dogs is that harvesting their eggs is extraordinarily labor intensive. You can get cow eggs from a slaughterhouse and incubate them to maturity in the lab. But because very few dog eggs will mature outside of a dog, viable eggs have to be extracted surgically. Once you have inserted the DNA you want to clone and tricked the eggs into becoming embryos, moreover, you can't just implant them at will in a surrogate bitch. Cows, goats and sheep can be thrown into estrus--readiness for pregnancy--by giving them a hormone shot. Not dogs. "You have to monitor hundreds, if not thousands, of dogs every day to figure out when they come into heat," says Westhusin. That's why Hwang's team--which stays on the job seven days a week for 18 to 20 hours a day--was well matched for the task. "We had to be ready to collect oocytes at any time of day, even midnight or early morning," says Hwang, adding, in a masterpiece of understatement. "Our work style helped, indeed."
But it may not help pet owners. Cloning Snuppy (the name comes from "Seoul National University puppy") took nearly three years and cost millions of dollars. Hwang's ultimate motive, he says, is to create a research model for making stem cells that could cure disease in people. "Compared with rodents," he says, dog cells "are more similar to human stem cells." GS&C still wants to capture the Fido-cloning market, though, and company scientists are trying to reduce the inefficiencies. Even if they manage to clone a dog, says Ben Carlson, a company spokesman, it won't be cheap. "We're charging $32,000 for a cat," he says, "and it will be more for dogs."