In a breakthrough that redefines how life can be created, embryologists working at the University of Cambridge in the UK have grown realistic-looking mouse embryos using only stem cells. No egg. No sperm. Just cells plucked from another embryo.
Synthetic human embryos would be a boon to scientists, letting them tease apart events early in development. And since such embryos start with easily manipulated stem cells, labs will be able to employ a full range of tools, such as gene editing, to investigate them as they grow.
Artificial embryos, however, pose ethical questions. What if they turn out to be indistinguishable from real embryos? How long can they be grown in the lab before they feel pain? We need to address those questions before the science races ahead much further, bioethicists say. —Antonio Regalado