Advertisement “We have gathered a lot of knowledge on animal models … but that knowledge doesn’t always translate to humans because we are different from other animals,” Izpisua Belmonte said. “About 20 years ago, the scientific community was able to get some of these cells from these early embryos [known as] totipotency cells that can generate the 250 cell types that a human is composed of. … We were able to take them out of a human embryo, put them in a petri dish and maintain them. In these 20 years, we have taken these cells and are trying to mimic what nature will do: Inside the mother, these cells will start to form all the tissues and organs, so we are trying to mimic that process in a petri dish.”