Neuroscientists may have crossed an "ethical rubicon" by growing clumps of human brains in the lab, and in some cases transplanting the tissue into animals, researchers warn.
The creation of mini-brains or "organoids" in the brain has become one of the hottest areas of modern neuroscience. Tissues are made of stem cells, and although only on one pea, some have developed spontaneous brain waves, similar to those seen in premature babies.
Many scientists believe that organoids have the potential to transform medicine by allowing them to examine the living brain as never before. But the work is controversial as it is unclear where it can cross the line to human experimentation.
On Monday, researchers will tell the world's largest annual meeting of neuroscientists that some scientists working with organoids are "dangerously close" to cross ethics, while others may have already done so by creating sensitive lumps in the lab.
"If there is even a possibility that the organoid is sensitive, we can cross that line," said Elan Ohayon, director of the Green Neuroscience Laboratory in San Diego, California. "We don't want people to do research where there is the potential to suffer from something."
Due to the obvious difficulties in studying living human brains, organoids are considered a milestone development. They have been used to investigate schizophrenia and autism, and why some children develop small brains when infected with the Zika virus in the uterus. Researchers hope to be able to use organoids to study a variety of heart diseases, from Alzheimer's to Parkinson's, and eye diseases such as age-related macular degeneration.
But in his presentation to the Society for Neuroscience meeting in Chicago, Ohayon and his colleagues Ann Lam and Paul Tsang will argue that controls must be in place to ensure that brain organoids do not experience suffering. "We already see activity in organoids that is similar to biological activity in developing animals," Ohayon said.
In a new study, researchers at Harvard showed that organ organoids in the brain develop a rich variety of tissues, from cerebral neurons to retinal cells. Organoids grown for eight months developed their own neuronal networks that sparked with activity and responded when the light shone on them. In another study led by Fred Gage at the Salk Institute in San Diego, researchers transplanted human brain organoids into mouse brains and found that they joined the animal's blood supply and sprouted new connections.
Ohayon wants funding agencies to freeze all research aimed at putting human brain organoids into animals, along with other work where there is a reasonable chance that organoids will become sensitive. Ohayon has developed computer models that he believes help identify when perception is likely to arise, but adds that there is an "urgent need" for more work in the area.
In the UK, researchers are already prohibited from working with donated embryos older than 1
Last year, a group of scientists, lawyers, ethics and philosophers called for an ethical debate about organ organoids in the brain. The authors, including Hank Greely, director of the Center for Law and Biosciences at Stanford University in California, said that organoids were not yet sophisticated to raise immediate concerns, but that it was time to start discussing guidelines.
Greely said there was no single ethical line when it came to organoids. "I'm convinced they don't think we've reached a Gregor Samsa state, where a person wakes up and finds himself an organoid," he said, referring to the character in Franz Kafka & # 39; s The Metamorphosis waking up to find he is a giant insect. But he added: "If they mean the potential to perceive or react to things, it probably seems to me."
Greely believes that worries will become more serious if organoids perceive and respond to stimuli that can cause pain. "It becomes even more important if we have reason to believe that the organoid has an aversive reaction to that stimulus, that it" feels pain. "I highly doubt that anyone has reached that point or come close to it," he added.
Gage told the Guardian: "I think it is never too early to raise issues of ethics in science, so that a thought-provoking dialogue can guide scientific research and decision making."