First human-pig chimera

On 26 January 2017, scientists at the Salk Institute for Biological Studies in La Jolla, California, USA, announced to the world that they had successfully combined stem cells from a human and a pig embryo to create the first inter-species chimera (from the Greek cross-species animal) for the two distantly related species. The aim is to ultimately grow human organs for transplant within pigs. In the scientists' work, human stem cells were injected into pig embryos, leading to more than 2,000 hybrids that could then be re-transplanted into surrogate sows. More than 150 of the embryos developed into chimeras that were mostly pig, but with a tiny human portion – around one in 10,000 cells.