After years of trial and error, scientists have finally done something incredible: They have successfully grown human stem cells in a pig embryo. Why would anyone do this? Turns out, many ...

are pioneers in the field of interspecies chimera research, the study of organisms containing cells from two different species. Their team focuses on using human induced pluripotent stem cells to grow ...

hoping that the pigs' kidneys would have human cells. Most recently, experiments by Juan Carlos Izpisua Belmonte and his team at the Salk Institute created a human-monkey chimera embryo.