American scientists have successfully 3D printed functional human brain tissue
American scientists have successfully 3D printed functional human brain tissue for the first time, capable of growing and functioning like traditional brain tissue. The related research was published on February 1st in the journal Cell Stem Cell.
Scientists believe that this breakthrough has significant implications for studying the brain and treating a variety of neurodegenerative and neurodevelopmental diseases, such as Alzheimer’s and Parkinson’s disease.
Co-author of the study, Professor Su-Chun Zhang from the Waisman Center, Neuroscience and Neurology at the University of Wisconsin-Madison, states that the brain tissue could be a powerful model to help understand how human brain cells communicate with each other. "It could change our understanding of stem cell biology, neuroscience, and the pathogenesis of many neurological and psychiatric diseases," he said.
The researchers note that previous printing techniques limited the potential for printing brain tissue. They did not use the traditional vertical layering associated with 3D printing; rather, they utilized a horizontal layering approach, placing brain cells derived from induced pluripotent stem cells into a soft "bio-ink" gel, eventually cultivating neurons.
"The tissue has enough structure to be interconnected, and the soft environment promotes neuronal growth and communication. Our tissue is relatively thin, which allows neurons to obtain enough oxygen and nutrients from the growth medium with ease," says Zhang Su-Chun.
Cells are aligned like pencils on a desktop. The printed cells form connections within and between each printed layer through the medium, establishing a network comparable to a human brain. Neurons communicate using neurotransmitters, send signals, interact, and even form proper networks with support cells added to the printed tissue.
The research team printed the cerebral cortex and striatum, and the results were astonishing. The cells from different parts of the brain communicated with each other in a very specific way, despite the cells being different types. This printing technique allows precise control over the type and arrangement of cells, something mini-brains or brain organoids, miniature organs used for brain research, cannot do.
Researchers claim they can produce almost any type of neuron at any given time, thus being able to assemble them in any desired way. By designing the tissue to be printed, researchers can observe how human brain networks operate through a clear system and even see how neurons communicate with each other under specific conditions.
Beyond specificity, this 3D printing technology also offers flexibility. The printed brain tissue can be used to study signaling between cells in Down syndrome patients, the interaction between healthy tissue and tissue affected by Alzheimer's disease, test new candidate drugs, and observe brain growth to study brain development, human development, developmental disorders, and potential molecular mechanisms in neurodegenerative diseases.
It is noteworthy that this new 3D printing technique can be applied to various laboratories, as it does not require special bioprinting equipment or culture methods to maintain tissue health and can be studied in depth using microscopes, standard imaging techniques, and electrodes common in the field.
Going forward, researchers hope to tap into the specialization potential, further improving the "bio-ink" and equipment to achieve specific orientations of cells within the printed tissue. Currently, the printer used in the lab is a commercial desktop printer. Zhang Su-Chun mentions plans for specialized improvements that allow for on-demand printing of specific types of brain tissue.
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