Until now, scientists believed that brain organoids were only representative of the fetal brain, however, new research has shown that brain-like organoids grown in the lab follow an internal clock genetically mirroring pre- and postnatal human brain development. Recent findings suggest that brain organoids could have a wider application and may also be useful in studying adult-onset diseases such as dementia.
Senior author, Professor Daniel Geschwind of the University of California Los Angeles (UCLA), said 'This will be an important boost for the field. We've shown that these organoids can mature and replicate many aspects of normal human development – making them a good model for studying human disease in a dish'.
Researchers at UCLA and Stanford University, California, used a type of stem cell called induced pluripotent stem cells (iPSCs). These are obtained from skin and blood and turned back into embryonic stem cells, which are then able to form any cell in the body. With time, under specific conditions, iPSCs can self-organise into 3D structures representative of a brain region.
By growing these organoids for up to 20 months, and periodically running genetic analyses, researchers showed that several aspects of human brain development were replicated. The organoids even showed physiological changes at around 280 days (approximately nine months) correlating to changes in the newborn brain, suggesting maturation.
Dr Sergiu Pașca of Stanford University, also a senior author, told Science that a striking discovery from this research is that despite the unnatural environment in which they are grown, 'the cells just know how to progress'.
Brain organoids are already used to study a range of disorders including epilepsy, autism, and schizophrenia. They are not considered conscious, and lack many aspects of the human brain including sensory inputs, blood vessels, and immune cells. However, they can still provide a valuable tool in studying development, disease, and potential therapies. The use of iPSCs also means that brain organoids could be grown from patients with genetic brain disorders, potentially allowing scientists to investigate neurodegeneration, a process that is currently difficult to study.
Dr Madeline Lancaster, of the MRC Laboratory of Molecular Biology, Cambridge, commented to Science: 'Things that, before I saw this paper, I would have said you can't do with organoids… actually, maybe you can'.
The paper was published in Nature Neuroscience.