Puppies Born by In Vitro Birth for First Time; Learnings for Gene-Editing Diseases

A litter of puppies was born by in vitro fertilization for the first time, as a result of Cornell University research.

The study was recently published in the journal Public Library of Science ONE, and the researchers say their findings provide solid steps toward conserving endangered canid species. The conservation could use gene-editing technologies to eliminate diseases that dogs inherit, and to study genetic diseases. In fact, between humans and canines there are 350 similar heritable traits and disorders; this is nearly twice as many as other species have in common with humans.

In the study birth, 19 embryos were implanted into the host female dog. She gave birth to seven puppies in good health. Two of them were from a beagle mother and a cocker spaniel father; five were from two sets of beagle mothers and fathers, according to a release.

"Since the mid-1970s, people have been trying to do this in a dog and have been unsuccessful," Alex Travis, associate professor of reproductive biology at Cornell, said in the release.

Clearly, there have been stumbling blocks. It has been hard to work out how to fertilize a mature egg using sperm in a lab and bring about an embryo. Secondly, the embryo must be returned to a host female at the correct moment in her reproductive cycle, which occurs once or twice a year.

In order to begin doing that, the study gathered mature eggs from the female oviduct (called Fallopian Tubes in human women). Their earlier attempts failed, but later first author Jennifer Nagashima, a graduate student in Travis' lab, and her colleagues, learned to leave the egg for a bit longer to achieve greater readiness for fertilization.Then they realized that if they added magnesium to a certain cell culture in the lab, this made the sperm ready for fertilization, too.

"We made those two changes, and now we achieve success in fertilization rates at 80 to 90 percent," Travis said in a statement.

Also, because the team was able to freeze the embryos, they could wait for the best moment (once or twice a year) to insert them into the mother dog's oviducts, said the statement.

"With a combination of gene editing techniques and (in vitro fertilization), we can potentially prevent genetic disease before it starts," Travis said in the release. 

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