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Stem cell research has allowed medicine to go places that were once science fiction. Using stem cells, scientists have manufactured heart cells, brain cells and other cell types that they are now transplanting as a form of cell therapy. Eventually, the field anticipates the same will be possible with organs.
A new paper in AJOB Neuroscience by a group led by Tsutomu Sawai, of Kyoto University, reviews the ethical implications of research on brain organoids.
"Organoids" are organ-like structures. By recapitulating normal development, organoids have proven to be invaluable tools for understanding how organs grow and how diseases develop. Organoids have been reported for an assortment of organs, including the liver, kidney and, most controversially, the brain.
The brain is considered the source of our consciousness. Therefore, if brain organoids do mimic the brain, they could develop consciousness, which, involves all sorts of moral implications.
"Consciousness is a very difficult property to define. We do not have very good experimental techniques that confirm consciousness. But even if we cannot prove consciousness, we should set guidelines, because scientific advancements demand it," says Sawai.
With some people imagining a future where our brains are uploaded and kept on the cloud well after our bodies die, organoids bring an opportunity to test consciousness and morality in artificial environments, the article contends.
Ethicists have broken consciousness down into many types. Phenomenal consciousness assumes the awareness of pain, pleasure and distress. Sawai and his colleagues argue that even though restraints on experiments using brain organoids would be needed, phenomenal consciousness would not outright prohibit experiments, since animals commonly used in science, such as rodents and monkeys, also display phenomenal consciousness. Self-consciousness would add to the ethical conflicts, since this status bestows a higher morality.
However, Sawai says that there is a more pressing issue.
"One of the biggest problems is transplants. Should we put brain organoids into animals to observe how the brain behaves?"
While growing whole human brains inside animals is not under any serious consideration, transplanting brain organoids could give crucial insight on how diseases like dementia or schizophrenia form and treatments to cure them.
"This is still too futuristic, but that does not mean we should wait to decide on ethical guidelines. The concern is not so much a biological humanization of the animal, which can happen with any organoid, but a moral humanization, which is exclusive to the brain," said Sawai.
Other concerns, he added, include enhanced abilities -- think Planet of the Apes. Furthermore, if the animal developed humanized traits, then treating it sub-humanely would violate human dignity, a core tenet of ethical practice.
The paper notes that some people do not consider these outcomes unethical. Enhanced abilities without a change in self-consciousness is equivalent to using a higher animal in experiments, like shifting from mouse to monkey. And a change in dignity does not mean a change to human dignity. Instead, the change could result in a new type of dignity.
Regardless, the authors believe that the possibility of unintended connections between the transplanted brain organoid to the animal brain deserves precautionary consideration.
The biggest concern regarding brain organoid transplantation, however, does not involve animals. There is good reason to believe that as research proceeds, the future will bring the possibility of transplanting these structures into patients who suffered from sudden trauma, stroke or other injury to the brain.
There are already a number of clinical trials that involve the transplantation of brain cells as a cell therapy in patients with such injury or neurodegenerative diseases. Sawai said that the ethics behind these therapies could act as a paradigm for brain organoids.
"Cell transplantations change the way brain cells function. If something goes wrong, we can't just take them out and start over. But right now, cell transplantation is usually in just one location. Brain organoids would be expected to interact more deeply with the brain, risking more unexpected changes," he believes.
Michael Cook is editor of BioEdge
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