Cerebral organoids: ethical issues and consciousness assessment

Organoids are three-dimensional biological structuresgrown in vitro from different kinds of stem cells that selforganisemimicking real organs with organ-specific celltypes. Recently, researchers have managed to producehuman organoids which have structural and functionalproperties very similar to those of different organs, suchas the retina, the intestines, the kidneys, the pancreas,the liver and the inner ear. Organoids are considered agreat resource for biomedical research, as they allow fora detailed study of the development and pathologiesof human cells; they also make it possible to test newmolecules on human tissue. Furthermore, organoidshave helped research take a step forward in the field ofpersonalised medicine and transplants. However, someethical issues have arisen concerning the origin of thecells that are used to produce organoids (ie, humanembryos) and their properties. In particular, there arenew, relevant and so-far overlooked ethical questionsconcerning cerebral organoids. Scientists have createdso-called mini-brains as developed as a few-monthsoldfetus, albeit smaller and with many structural andfunctional differences. However, cerebral organoidsexhibit neural connections and electrical activity, raisingthe question whether they are or (which is more likely)will one day be somewhat sentient. In principle, thiscan be measured with some techniques that are alreadyavailable (the Perturbational Complexity Index, a metricthat is directly inspired by the main postulate of theIntegrated Information Theory of consciousness), whichare used for brain-injured non-communicating patients.If brain organoids were to show a glimpse of sensibility,an ethical discussion on their use in clinical research andpractice would be necessary.