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A team of scientists at the University of Wisconsin-Madison claim to have 3D-printed functional human brain tissue for the first time.

They hope their research could open the doors for the development of treatments for existing neurological disorders, including Alzheimer's and Parkinson's disease.

As detailed in a new paper published in the journal Cell Stem Cell, the team flipped the usual method of 3D-printing on its side, fabricating horizontal layers of brain cells encased in soft "bio-ink" gel.

"The tissue still has enough structure to hold together but it is soft enough to allow the neurons to grow into each other and start talking to each other," said coauthor and UW–Madison neuroscience professor Su-Chun Zhang in a statement.

Thanks to this arrangement, each of these neurons, which were grown from pluripotent stem cells, had enough access to oxygen and nutrients from growth media.

In experiments, the cells started forming networks, much like the human brain, and could even communicate with each other through the neurotransmitters they formed.

"We printed the cerebral cortex and the striatum and what we found was quite striking," Zhang explained in the statement. "Even when we printed different cells belonging to different parts of the brain, they were still able to talk to each other in a very special and specific way."

Zhang says the 3D-printed cells have a key advantage over organoids, the "mini-brain" tissue models scientists already use to study the brain.

"Our lab is very special in that we are able to produce pretty much any type of neurons at any time," Zhang said. "Then we can piece them together at almost any time and in whatever way we like."

"We can look very specifically at how the nerve cells talk to each other under certain conditions because we can print exactly what we want," he added.

Thanks to that flexibility, the team is hoping such a system could be used to study how cells talk to each other, for instance in tissue affected by Alzheimer's. The tissue could also be used to evaluate new drug candidates.

"In the past, we have often looked at one thing at a time, which means we often miss some critical components," Zhang explained in the statement. "Our brain operates in networks. We want to print brain tissue this way because cells do not operate by themselves. They talk to each other."

Best of all, Zhang and his colleagues used a commercially available bioprinter, which could allow other institutions to print their own human brain tissue.

The team is now looking for ways to print cells at predefined orientations, which could allow them to get even more control over the types of brain tissue they can manufacture.

"This could be a hugely powerful model to help us understand how brain cells and parts of the brain communicate in humans," Zhang said. "It could change the way we look at stem cell biology, neuroscience, and the pathogenesis of many neurological and psychiatric disorders."