Photo of the National Center for Advancing Translational Science (NCATS) laboratories and researchers of their Division of Pre-clinical Innovation (DPI).

Image credit: National Center for Advancing Translational Science via Flickr



Scientists have raised ethical concerns over rapidly advancing work growing human brains.

This month at the annual Society for Neuroscience meeting, scientists from the Green Neuroscience Laboratory in San Diego called for a suspension on mini-brain research until an ethical framework guide had been developed. They warned that some researchers are becoming “perilously close” to creating sentient tissue and crossing an ethical line.

Mini-brains are a type of organoid, a tiny simplified version of an organ produced in the lab from human stem cells. Organoids are a fast-developing field of biology – in just a few years scientists have moved from growing flat sheets of cells, to three-dimensional structures made up of many cell types and functioning physiologies. Scientists can replicate natural cell environments in cell culture dishes, which allow stem cells to self-organise into structures as if they were developing in vivo. From a scientific point of view, the potential for this field is huge. Organoids provide insights into specifically human development, so they may be more relevant for studying disease than animal models. They also provide an opportunity to test drugs on functioning organs, hence revolutionising drug discovery. They have been used to investigate complex conditions that are infamously difficult to study, including schizophrenia and autism. From a practical point of view, organoids are an economic alternative to animal testing – one lab calculated that each mini-brain cost only 25 cents, and protocols for producing them are now relatively simple.

Organoids provide insights into specifically human development, so they may be more relevant for studying disease than animal models.

These organoids have rapidly increased in complexity, which in terms of mini-brains raises ethical concerns about developing sentience . Until recently, scientists had grown tissue containing collections of active neurons, however, none had shown network activity which mimics a real functioning brain. By tweaking the molecular mixture used in the cell culture dishes, a team at the University of California were able to allow their mini-brains to develop for a longer period of time. Although tiny, they saw that after a few months their tissues developed electrophysiological features similar to those seen in premature babies. Another lab grew mini-brains that developed neurons which were responsive to light, like photoreceptors in normal human brains. As mini-brains can now carry out basic physiological functions, the question is, at what point would they be considered sentient and, considering that these are grown from human stem cells, where does the line into human experimentation lie?

Sentience does not encompass self-awareness but does cover the ability to perceive the environment and experience sensations such as pain or pleasure. It is this ability to perceive pain that some scientists are concerned about. Although the idea of a mind awakening and discovering that it is just a lump of tissue with no body is still a sci-fi concept, the possibility that an organoid can perceive and respond is fraught with a risk of suffering.

The Green Neuroscience Laboratory,is a non-profit research lab in San Diego which is aiming for a new and more sustainable approach to neuroscience that eliminates “toxic methodologies”. Presenting to the Society for Neuroscience, they asserted that research be put on hold until guidelines have been determined. Scientists, lawyers, ethicists and philosophers must all be involved in this debate.

Sentience does not encompass self-awareness but does cover the ability to perceive the environment and experience sensations such as pain or pleasure.

Although mini-brains are currently far from the complexity of human or animal brains, the Green team believe that these mini-brains are dangerously close to becoming fundamentally sentient. They have developed computational models to help predict when sentience will arise, but pointed out that much more work is required on top of this to build up an ethical framework.

These concerns have been echoed by other neuroscientists, some pointing out that particular consideration needs to be made for experiments in which organoids are transplanted into animal hosts. Several cases of science outpacing ethics have arisen in recent years. Just months ago, similar concerns around sentience and suffering were raised after a lab successfully revived a dead pig brain, propelling the realisation that scientific ethics are quickly becoming outdated for this emerging cutting-edge neuroscience.

They have developed computational models to help predict when sentience will arise.

The explosion of knowledge and technology in recent decades means science has become something of a race. It is crucial that pressure on scientists to discover, publish and to obtain and maintain funding does not infringe on their first and foremost duty to minimise harm. Ethics are crucial to sustainable science – they are essential to collaborative work, and ensure that researchers can be held accountable by the public. With such exciting opportunities for drug discovery and disease research, it is paramount that the future of this field is not jeopardised by haste in its early days.

Written by Ailie McWhinnie and edited by Tara Gamble.