Just one seemingly tiny error during the early stages of brain development can have an enormous impact on a person's life. Finding such errors will likely be critical to one day prevent developmental disorders such as autism — but studying the developing brain in humans presents many challenges.
To get around these challenges, scientists came up with a way to take skin cells from patients, convert them into brain cells, and grow them up into miniature brain "organoids" in a dish. This extremely useful brain-in-a-dish method was only introduced a couple of years ago, and now researchers report in the journal Cell that they have gained new insights into autism by studying brain organoids grown from the skin cells of patients with the disorder. By growing a brain organoid from the cells of patients with enlarged brains – a distinctive trait associated with more severe autism symptoms – the researchers were able to identify key developmental differences that could one day be used to prevent this type of autism.
"This is the first time the brain organoid approach has been used to study autism," senior study author Flora Vaccarino told Tech Times. "You can recapitulate development in a dish – all of the genes that are activated during development, the cells that are generated – there's no other way to do that."
Because autism is a developmental disorder, researchers must look at the way the brain changes early in life to properly study how it arises. That's possible in the unfortunate case of an autistic child dying, with the parents donating the child's brain to science — but those brains are of course very scarce. Plus, these brains are not as useful as the brain organoids; they show only a static snapshot of a brain that has already gone through many of the major stages of brain development.
Brain organoids afford researchers the unique opportunity to study how brain development occurs dynamically and in those crucial early stages. This is especially useful for autism research, because autism is a very complex disorder with many different causes. The list of genes associated with autism continues to grow, but these genes account for only about 20 percent of autism cases.
For the most part, "we really don't know what's going on in autistic brains," according to Vaccarino.
By focusing on autism patients who have enlarged brains, Vaccarino and her colleagues hoped to home in on just one subgroup of autism. They took skin cell samples from four such patients and their parents, for comparison, and used them to grow brain organoids that mimicked the development of a brain in an embryo 10 to 16 weeks old. (The image above shows one of the brain organoids used in the study, each of which measured just millimeters across.) In particular, they looked at the cerebral cortex — the seat of higher brain functions like complex thought.
The brain organoids of the autistic patients showed a marked imbalance between two types of neurons and increased levels of expression of a gene active in brain development, the researchers found. By suppressing that one gene, they were actually able to restore balance to the brain organoids. This result hints at the possibility of regulating genes that cause autism to restore normal brain function before a child is born.
Vaccarino cautions that it is still too early to say how this research might lead to clinical interventions, but notes that "this is something that [I, as well as] others, will be exploring."
Autism is only the beginning for brain organoid research. This technique can likely provide insights on a variety of other human brain disorders ranging from schizophrenia to addiction.
Photo: _DJ_ | Flickr
