Dear colleagues and friends,
The products that are being printed with 3D printers today have achieved impressive sophistication. As an example, a dear colleague shares this article, written by Emily LeClerc, published in the newsletter of the University of Wisconsin-Madison (UW-Madison) and translated by us for this space. Let's see what it's about...
A team of UW-Madison scientists has developed the first 3D printed nerve cell-based tissue that can grow and function like typical human nervous tissue.
It's an achievement with important implications for scientists who study the brain and work on treatments for a wide range of neurodevelopmental disorders and diseases, such as Alzheimer's and Parkinson's.
“This could be an enormously powerful model to help us understand how nerve cells and parts of the brain communicate in humans,” says Su-Chun Zhang, professor of neuroscience and neurology at the Waisman Center at UW-Madison. “It could change the way we view stem cell biology, neuroscience, and the pathogenesis of many neurological and psychiatric disorders.”
Printing methods have limited the success of previous attempts to print nerve tissue, according to Zhang and Yuanwei Yan, a scientist in Zhang's lab. The group developing this new 3D printing process describes their method in the journal Cell Stem Cell.
Instead of using the traditional 3D printing approach, stacking layers vertically, the researchers chose to do so horizontally. They put nerve cells, neurons grown from induced pluripotent stem cells, in a softer “biological ink” gel than had been used in previous attempts.
“The tissue still has enough structure to hold together, but it's soft enough to allow neurons to grow into each other and start communicating with each other,” Zhang says.
The cells are placed side by side like pencils placed side by side on a table.
“Our tissue stays relatively thin and this makes it easier for neurons to get enough oxygen and enough nutrients from the growth medium,” Yan says.
The results speak for themselves, that is, cells can communicate with each other. The printed cells cross the medium to form connections within each printed layer, as well as between layers, forming networks comparable to human brains. That is, neurons communicate, send signals, interact with each other through neurotransmitters, and even form suitable networks with support cells that were added to the printed tissue.
“We printed the cerebral cortex and striatum and what we found was quite surprising,” Zhang says. “Even when we printed different cells belonging to different parts of the brain, they could still communicate with each other in a very special and specific way.”
The printing technique offers precision (control over cell types and arrangement) not found in brain organoids, miniature organs used to study the brain. Organoids grow with less organization and control.
“Our laboratory is very special because we can produce practically any type of neuron at any time. Then we can assemble them any way we want,” Zhang says. “Because we can print fabric by design, we can have a defined system for observing how our human network operates. We can observe in a very specific way how nerve cells communicate with each other under certain conditions because we can print exactly what we want to observe.”
