Brain tissue grown in a lab has been for the first time spontaneously exhibited electrical activity. The ‘brains’ were developed in a lab at the University of California, San Diego showed signs of brain activity usually seen in premature babies.
The report on the outcome isn’t peer-reviewed yet, but if it gets the green light for publication, it could change the way we understand the early development of brain disorders. Lab-grown brains are known as organoids.
Simple organs grown for testing and observation
They are miniature 3D simplified versions of organs used for testing drugs and other research such as cell development under particular conditions. Neuroscientist Alysson Muotri has been involved with growing organoids in his lab for years but this is the first time such as result has been seen.
The experiment involved growing the organoids from human pluripotent stem cells or stem cells that can become any other kind of cell. These ‘blank’ cells were used to develop into cells from the cerebral cortex, the part of the brain that deals with memory, perception, cognition, thought, and sensory processing.
Brains revealed close similarities to pre-term babies
Muotri and his team grew hundreds of these tiny brains over a 10 month period. Continual testing was carried out to ensure the right genes for brain development were being expressed.
Each brain was also constantly monitored the organs with electroencephalography (EEG). The team reported that after 6 months of growth the tiny brains were expressing energetic brain activity, more than in previous studies.
Human-like activity clearly detected
However, the energy wasn’t like that of a regular human adult with predictable and organised activity. The waves were in fact more similar to the brain activity seen in preterm infants.
"While network activity from organoids does not exhibit the full temporal complexity seen in adults, the pattern of alternating periods of quiescence and network-synchronized events is similar to electrophysiological signatures present in preterm human infant EEG," the researchers wrote in their paper.
Further research will extend the understanding of brain disorders
The brain patterns weren’t exactly the same as premature babies but a machine learning model trained on preterm EEG signatures was able to identify many features in common with a normal developmental timeline. After the 28 week mark, the organoids appeared to be developing in a manner very similar to a pre-term baby of the same age.
"While we do not claim functional equivalence between the organoids and a full neonatal cortex," the researchers wrote, "the current results represent the first step towards an in vitro model that captures some of the complex spatiotemporal oscillatory dynamics of the human brain." The researchers are going to continue to try to develop the brainlets further to see if they continue to mature.
The research was presented at the Society for Neuroscience annual meeting in early November and has been published on preprint resource bioRxiv.