Scientists Successfully Start Growing Human-Pig Hybrid in Lab


Scientists announced last week that they had created the first human-animal hybrid in their lab. Like something out of a science-fiction novel, this successful experiment involved injecting human stem cells inside early-stage pig embryos. The project proves that human cells can be introduced into non-human organisms, survive, and even grow inside a host animal. The implications for developing human organs inside animals for transplant are staggering, along with the ethical ramifications.

Described as interspecies chimeras, researchers in the US implanted human cells into pig embryos that were then transferred into surrogate sows and allowed to develop until the first trimester. More than 150 of these embryos developed into chimeras- they grew precursors of organs including the heart and liver. They contained a small amount of human cells, around one in 10,000 of the hybrids’ cells were human.

This biomedical advancement has long been a dream and dilemma for scientists hoping to address a critical shortage of donor organs. Every ten minutes, another person is added to the national waiting list for organ transplants, but every day 22 people die without the organ they desperately need. Now biologists may be able to change this staggering statistic by growing custom-created organs inside a host animal.

Organ development was one of the driving motivations of the international team of researchers, led by the Salk Institute. Published in the scientific journal Cell, lead study author Jun Wu defends the controversial project. The term chimera comes from a legend in Greek mythology describing a monster who was often depicted as a lion with a goat’s head sticking from the side of its neck and a snake for a tail, but in biology, the word is defined as an organism that contains cells from two different species. But the remnants of the monster connotations still remain in society. These experiments are currently ineligible for public funding in the US, and public opinion has hampered the creation of organisms that are part human and part animal. Relying on private donors for this project, Wu and team member Juan Carlos Izpisua Belmonte (also from the Salk Institute) have shown that our stem cells can contribute to forming the tissues of a pig despite the 90 million years of evolution separating our species.

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