Brain waves detected in lab-grown mini brains.
As human brain tissue is difficult to obtain, stem cells are used to develop mini brains or ‘organoids’, a pea-sized model of the human brain, in a lab dish. By growing them in culture medium which mimics the environment of brain development, the stem cells self-organize into a 3D structure that resembles the developing human brain. However, only a handful of studies have successfully used 3D cell culture techniques which have achieved this. Now, a study from researchers at University of California, San Diego engineer miniature brains from stem cells which spontaneously develop functional neural networks. The team state despite being a million times smaller than human brains, their lab-grown brains are the first to produce brain waves resembling those of preterm babies. The opensource study is published in the journal Cell Stem Cell.
Previous studies show research in early brain development has been slow, partly because it is difficult to obtain fetal-tissue samples for analysis and to examine a fetus in utero. Therefore, there is much excitement around the development of brain ‘organoids’, which, when grown in 3D cultures, can develop some of the complex structures seen in brains. However, there is no evidence that these organoids develop complex and functional neural network activity, networks which appear when neurons are mature and become interconnected, that are essential for most brain activities. The current study develops lab-grown brains which form intricate networks of neurons that produce strong brain waves.
The current study optimizes the 3D culture medium formula which allows brain organoids to become more mature than previous models. Hundreds of organoids were grown for 10 months, using multi-electrode arrays to monitor their neural activities. Results show that bursts of brain waves were detected from organoids at about two months. Data findings show the signals were sparse and had the same frequency or pattern seen in very immature human brains.
Results show as the organoids continued to grow, they produced brain waves at different frequencies, with the signals appearing more regularly, suggesting the organoids further developed their neural networks. The lab explain to compare the brain wave patterns of organoids with those of human brains early in development, they used an algorithm with brain waves recorded from 39 premature babies between six and nine-and-a-half months old. They go on to add the algorithm was able to predict how many weeks the organoids have developed in culture, which suggests these organoids and human brain share a similar growth trajectory. They stress it’s not likely these organoids have mental activities, such as consciousness.
The team surmise they have detected functional brain waves from mini-brains they grew in lab. For the future, the researchers state findings suggest that these organoids are suitable for the investigation into network formation at early and late stages of the human brain development.