Scientists Create Human Animal Hybrid With A Pig, Hoping To Grow Transplantable Organs

Scientists at the Salk Institute for Biological Studies in California have created the first human animal hybrid with a pig grown in a lab. Using gene-editing and stem-cell technologies the scientists were able to create what they call interspecies chimera, publishing their results in the online research and review journal >Cell.

The technique involves them growing human cells and tissues in pig and cattle embryo, which is effectively the beginning of an animal human hybrid.

But before you worry about some Dr. Moreau type abomination, the embryo was terminated before a human chimera could be born. Due to the controversial nature and ethical questions of human animal hybrid experiments, the researchers were only allowed to grow the embryo for 28 days before destroying it.

It's the first step to a real human animal hybrid and what they hope will be a way to grow functional human organs—in animals whose organ size and physiology are similar to ours—which can then be used for transplants. It's also hoped it will help biologists study evolution and disease, along with testing therapeutic drugs for humans. Animal hybrids are nothing new in nature, but it has never with a human.

"Our findings may offer hope for advancing science and medicine by providing an unprecedented ability to study early embryo development and organ formation, as well as a potential new avenue for medical therapies," Phys.org report Salk Professor Juan Carlos Izpisua Belmonte, an author of the paper and expert in this field, as saying. "We have shown that a precisely targeted technology can allow an organism from one species to produce a specific organ composed of cells from another species. This provides us with an important tool for studying species evolution, biology and disease, and may lead ultimately to the ability to grow human organs for transplant."

Prior to injecting human stem cells into a pig's embryo, the scientists were able to grow a rat pancreas, heart, and eyes in a mouse, providing proof that functional organs from one species can be grown in another.

Rats and mice, however, are closer in evolutionary terms than pigs and humans, so the integration of cells from more divergent species will probably prove more difficult, but not impossible. It's a long way off yet though.

For the mice and rats they used gene editing tools which meant they were able to delete genes needed for organ creation while a mouse egg was developing. They then inject rat cells into it and the mouse embryo uses these to replace the deleted mouse genes.

And, according to Salk Institute staff scientist Jun Wu, the mice and rat experiment sets a precedent for animal hybrids showing that growing human organs in other animals using a similar technique is also possible. "Each mouse was healthy and had a normal lifespan, which indicated that the development proceeded properly." he said.

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This photograph shows injection of human iPS cells into a pig blastocyst. Credit: of Juan Carlos Izpisua Belmonte

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This visual abstract depicts the findings that human pluripotent stem cells robustly engraft into both bovine and porcine preimplantation blastocysts, but show limited chimeric contribution to postimplantation pig embryos. Credit: Wu et al./Cell 2017

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