Scientists create embryos without using egg or sperm cells. Can people grow out of this? And is that even allowed? The embryologist Michele Boiani on the need to rethink ethical assessments.
Most recently, two teams competed to create artificial human embryos from stem cells alone, without egg or sperm cells. In the running: researchers led by Magdalena Zernicka-Goetz from the University of Cambridge and the California Institute of Technology and Jacob Hanna from the Weizmann Institute in Israel. Now both groups have reached their goal, sometimes with different methods. They describe the embryos created as “models” for research: they resemble natural embryos that are six to 14 days old in some respects, but are not yet very differentiated, and there are no signs of the heart, brain or other organs. The embryologist Michele Boiani from the Max Planck Institute for Molecular Biomedicine in Münster explains how he assesses the development possibilities of these embryos – and why he does not want to speak of models.