Could we grow a brain in the lab?

What if you could grow a human brain in a petri dish?

Well, we’re not there yet, but the rise of 3-D human brain cell culture has opened the door to some exciting possibilities.

We spend a lot of time and resources studying mouse or rat brains. Ideally, though, we want to study human brains. Unfortunately, we can’t remove chunks of people’s brains to study in the lab.

“Will we be able to build an entire human brain from scratch someday?”

Brain “organoids” might be the next best thing. These are balls of human brain cells that begin as stem cells and grow in a dish in the lab. Most cell culture (growing cells outside of the body) is two-dimensional, meaning that cells stick to the surface of a dish and grow in a thin layer. This approach has worked pretty well so far for scientists, but a major limitation is that this is obviously not how cells behave in real life. Organoids, however, are suspended in liquid, so they can grow in three dimensions and more closely resemble real organs in their structure and behavior. By slightly manipulating the environment, scientists interested in the brain can coax stem cells to develop into different brain regions. They can also study interactions between brain regions by fusing organoids together to form “brain assembloids.”

Organoids and assembloids will almost certainly be key in modeling human brain development and progression of disease in the near future. Will we be able to build an entire human brain from scratch someday? Maybe not in our lifetimes, but a brain is no more than billions of cells that are organized in a specific structure. Once we can reproduce that design, what is stopping us from building a mind?