A group of scientists is calling for ethical guidelines for ‘mini-brain’ transplants in animals which could potentially invoke consciousness.

The transplantation of human ‘mini-brains’ – known as brain organoids – into animals is an increasingly popular research method to study disease. However, with this expansion comes ethical concerns from a group of researchers at the University of Pennsylvania School of Medicine.

Writing in Cell Stem Cell, the group said there is a minute chance that these grafted organoids could one day induce a level of consciousness in the creatures because they closer resemble human brains as they become more sophisticated.

A real pea-brain

The research group calls for an ethical framework that better defines and contextualises these organoids and establishes thresholds for their use. This latest paper accompanied another article which reported the presence of brain patterns – known as oscillatory activity – in brain organoids.

Brain organoids grown in the lab are currently no bigger than the size of a pea and are derived from human pluripotent stem cells. For the importance of research, they recapitulate important brain architecture and several basic layers of the human cortex, sharing many genetic similarities to the human brain.

However, this is where many of the similarities end. Those currently in use lack key cells for overall brain maintenance as well as other cell types that are essential for the organ to work. Yet the Pennsylvania research group warns that efforts to make ‘better’ brain organoids is progressing at a fast pace.

Avoiding potential pitfalls

“Current brain organoid transplantation is more likely to worsen brain function than improve it,” the authors wrote, “because transplantation involves the creation of a surgical cavity that likely leads to loss of function and a lack of connectivity.

“We argue that determining the degree to which an animal is similar to a human is less constructive than considering the possibility of specific brain enhancements and how these enhancements could influence an animal’s moral status.”

The group went on to note that regardless of the functional outcome of brain organoid transplantation, the host animal’s wellbeing and other socio-legal matters would need to be considered.

The study’s first author, H Isaac Chen, said: “While today’s brain organoids and brain organoid hosts do not come close to reaching any level of self-awareness, there is wisdom in understanding the relevant ethical considerations in order to avoid potential pitfalls that may arise as this technology advances.”