Ethical Issues in Cerebral Organoid Research.

About ten years ago, reports of lab-grown "mini brains" or "brains in a dish" appeared in the media, falling somewhere between the curious and the alarming. The trigger of these reports was a new method to grow three-dimensional neural tissue from human stem cells that recapitulates, to some degree, the early development of brain tissue. Despite their relatively small size and other limitations, such model systems capture in part the structure and functions of regions of the human brain and can also be combined to form so-called assembloids.