Building a better brain (model) in the lab

Leica Picture of a brain organoid: courtesy National Institute of Allergy and Infectious Diseases, NIH

One of the biggest problems with trying to understand what is happening in a disease that affects the brain is that it’s really difficult to see what is going on inside someone’s head. People tend to object to you trying to open their noggin while they are still using it.

New technologies can help, devices such as MRI’s – which chart activity and function by measuring blood flow – or brain scans using electroencephalograms (EEGs), which measure activity by tracking electrical signaling and brain waves. But these are still limited in what they can tell us.

Enter brain organoids. These are three dimensional models made from clusters of human stem cells grown in the lab. They aren’t “brains in a dish” – they can’t function or think independently – but they can help us develop a deeper understanding of how the brain works and even why it doesn’t always work as well as we’d like.

Now researchers at UCLA’s Broad Center of Regenerative Medicine have created brain organoids that demonstrate brain wave activity similar to that found in humans, and even brain waves found in particular neurological disease.

The team – with CIRM funding – took skin tissue from healthy individuals and, using the iPSC method – which enables you to turn these cells into any other kind of cell in the body – they created brain organoids. They then studied both the physical structure of the organoids by examining them under a microscope, and how they were functioning by using a probe to measure brain wave activity.

In a news release Dr. Ranmal Samarasinghe, the first author of the study in the journal Nature Neuroscience, says they wanted to do this double test for a very good reason: “With many neurological diseases, you can have terrible symptoms but the brain physically looks fine. So, to be able to seek answers to questions about these diseases, it’s very important that with organoids we can model not just the structure of the brain but the function as well.”

Next, they took skin cells from people with a condition called Rhett syndrome. This is a rare genetic disorder that affects mostly girls and strikes in the first 18 months of life, having a severe impact on the individual’s ability to speak, walk, eat or even breathe easily. When the researchers created brain organoids with these cells the structure of the organoids looked similar to the non-Rhett syndrome ones, but the brain wave activity was very different. The Rhett syndrome organoids showed very erratic, disorganized brain waves.

When the team tested an experimental medication called Pifithrin-alpha on the Rhett organoids, the brain waves became less erratic and more like the brain waves from the normal organoids.

“This is one of the first tangible examples of drug testing in action in a brain organoid,” said Samarasinghe. “We hope it serves as a stepping stone toward a better understanding of human brain biology and brain disease.”

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