Test tube puppies: First puppies born through IVF revealed
Published 09/12/2015 | 21:28
Puppies have been born through IVF for the first time leading to hopes that inherited diseases which plague many breeds could be prevented.
Scientists in the US unveiled a litter of seven healthy puppies, two from a beagle mother and a cocker spaniel father, and five from two pairings of beagle fathers and mothers.
The breakthrough opens the door for conserving endangered canine species and using gene-editing technologies to eradicate inherited diseases in dogs and even humans.
Thousands of years of domestication and inbreeding has left many dog breeds vulnerable to diseases. Golden retrievers, for example are likely to develop lymphoma, while Dalmatians carry a gene that predisposes them to blockage with urinary stones.
The puppies have been named Cannon, Red, Green, Cornelia, Buddy, Kiwi and Ivy le Fleur, a reference to 'In Vitro'.
However with the new technology, scientists could genetically edit the embryos of dogs before implantation to eradicate genetic problems.
"This is the world's first litter of puppies ever born through IVF. We have seven normal, happy, healthy puppies," said Alex Travis, associate professor of reproductive biology in the Baker Institute for Animal Health in Cornell's College of Veterinary Medicine.
"They all came from the same litter but they have different mums and dads. But they were all born at the same time and raised together
"Since the mid-1970s, people have been trying to do this in a dog and have been unsuccessful.
"Since dogs and humans share so many diseases, dogs now offer a powerful tool for understanding the genetic basis of diseases."
Canines share more than 350 similar heritable disorders and traits with humans, almost twice the number as any other species so the new technique could allow scientists to test genetic editing techniques on dogs, before applying them to humans, a practice which is currently banned.
For successful IVF, researchers must fertilise a mature egg with a sperm in a lab, to produce an embryo. They must then return the embryo into a host female at the right time in her reproductive cycle.
The first human baby conceived through IVF was Louise Brown who was born in 1978. But scientists have struggled to translate the technology to dogs' reproductive cycles differs significantly to other mammals which means their eggs take longer to mature and they can only be pregnant once or twice a year.
However, the team at Cornell discovered that if they left the eggs inside the dog for an extra day, they could be successful fertilised.
The reproduction system of a female dog also prepares sperm for fertilisation, so scientists had to find a way of reproducing the effect in the lab. Through trial and error, the scientists found that adding magnesium to the cell culture properly prepared the sperm.
The researchers then froze the embryos until the female dog was at exactly the right point of her reproductive cycle before implantation. Through the new techniques 19 embryos were created and transferred to a female dog with seven reaching full term.
"We made those two changes, and now we achieve success in fertilisation rates at 80 to 90 percent," added Dr Travis.
"The findings have wide implications for wildlife conservation because we can freeze and bank sperm, and use it for artificial insemination.
"We can also freeze eggs, but in the absence of in vitro fertilization, we couldn't use them. Now we can use this technique to conserve the genetics of endangered species."
Aimee Llewellyn, Head of Health and Research at the Kennel Club, said: “This breakthrough is extremely interesting, but it should be remembered that domestic dogs are not an endangered species, so this type of research is not necessary for species preservation as it may be for animals such as the Giant Panda or Black Rhino.
“New gene-editing technologies may be rather more novelty than necessity when it comes to domestic dog breeds, as there are a number of easier, non-invasive methods for dog breed conservation and the eradication of heritable diseases, such as DNA testing as part of a responsible breeding programme.
"This is particularly important given that a pet dog cannot consent to invasive treatments such as IVF as a human can. The Kennel Club supports research that directly benefits the domestic dog whilst ensuring the health and welfare of the animal remains top priority, which may not be the case when invasive procedures are involved"
The research was published in the journal PlOS One.