Scientists have created the first human-pig hybrid in a groundbreaking study that marks the first step in growing human organs inside animals.
Named chimera, after the cross-species beast in Greek mythology, the pig-human embryos were created in the Salk Institute for Biological Studies in La Jolla, California and are the first hybrid made using two large, distantly-related species.
“The ultimate goal is to grow functional and transplantable tissue or organs, but we are far away from that,” Juan Carlos Izpisua Belmonte, who led the project, said. “This is an important first step.” Human stem cells were injected into young pig embryos, which were then placed in surrogate cows. Of the more than 2,000 embryos, only 186 turned into chimeras – largely pig, with human elements in 1 out of 10,000 cells.
After 28 days of a pig’s 112-day pregnancy, the pig-humans were removed as scientists say the embryos had developed enough for them to study in what way the cells mix together “without raising ethical concerns about mature chimeric animals,” Izpisua Belmonte said.
As a pig’s gestation period of under four months is so much shorter than that of a human, the two species’ cells develop at different rates, providing a challenge for future chimera experiments. Despite excitement surrounding the pig-human, concerns have been raised about the ethical implications of mixing human with animal.There is a worry that humanized animals, or animals with human brains could pose a threat to humanity.