Human-Monkey Hybrid Embryo Created by Joint China–U.S. Scientist Team On 4/16/21 at 11:28 AM EDT A team of scientists from the U.S., China and elsewhere have developed embryos that are a mix of human and monkey cells for the first time in history. The embryos, which were detailed on Thursday in the scientific journal Cell, were created for scientists to uncover new ways to produce organs for people who need transplants. The researchers injected 25 stem cells from humans, known as induced pluripotent stem cells (or ISP cells), into embryos from macaque monkeys. The scientists then grew the mixed embryos in test tubes for up to 20 days in order to study how the animal and human cells communicate with one another.