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. (Click to Article)