Song explained to Seeker that he and other research teams are able to make brain region-specific organoids with “better reproducibility” and can start to use them to understand “basic mechanisms of brain development and brain disorders.”
He thinks it is theoretically possible to generate any structure of the human brain, but at present, scientists have reliably created forebrain (cortex), midbrain, and hypothalamus organoids.
Asked if brain organoids can think or exhibit other mental states, Song said, “I think it is an interesting question that we do not know the answer for at this moment, simply because we are not sure what constitutes consciousness.”
“We know that some brain organoids can mature and exhibit neuronal activity, and even patterns of neuronal activity,” he continued. “But currently brain organoids exhibit properties resembling properties of an early fetal brain up to the first and second trimester. As science and technology evolve, we need to revisit the question.”
Jonathan Kimmelman, an associate professor in the Biomedical Ethics Unit at McGill University, said there are two major ethical issues now at play concerning human brain organoids. The first, he said, relates to the welfare of animals.
“Introducing modifications to the nonhuman animal brain — whether through genetic modification, transplantation of cells, or transplantation of organoids — has the potential to alter an animal’s brain function,” he explained. “This can give rise to phenomena that are not typical for the species of the animal, and those phenomena can result in either greater suffering, or different behavioral needs that need to be addressed to minimize suffering.”
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For example, he said that a modification that causes heightened fear and anxiety in an animal has obvious potential to increase its suffering.
Josephine Johnston, director of research at the Hastings Center in New York, echoed this concern.
“I think that modifying animals to make them more human — or in some way more sentient, intelligent, conscious — whatever that means, etc. — raises animal welfare concerns and questions about the consequences of these changes for the animal’s moral status,” Johnston told Seeker.
Kimmelman said the second primary issue of concern over cerebral brain organoids is the prospect of animals acquiring human-like mental capacities or sentience.
“At this point in research, we are talking ‘science fiction’ and it is almost inconceivable in the context of rodent experiments,” he said. “Nevertheless, one would need to be extremely restrictive about authorizing — and allowing to continue — any experiment that has the prospect of conferring human-like mental capacities.”
Janet Rossant, a senior scientist in the developmental and stem cell biology program at the Hospital for Sick Children in Toronto, Canada, said steps should be put in place to try to restrict unwanted contributions to tissues other than the ones required for experiments.