For the first time, scientists have generated functional human brain tissue using a 3D printer.
The scientists printed the tissue to be less than 0.02 centimeters (0.01 in) thick and contained as much nerve cells and supporting cells called glia. All of these cells can communicate with each other and form networks, as they would in a real situation. human brain.
The tissue was created using a biological “printer” that produced stem cell-laden gel in horizontal layers. The stem cells were then convinced to become brain cells with chemicals that stimulate this development. The tissue layers were carefully stacked, one by one, on a laboratory plate to form a complete tissue model.
The researchers behind the printed fabric described their achievement in an article published February 1 in the journal. cell stem cell. They hope it will complement other models of the human brain; Such models, made from real human cells, more accurately represent the intricate and unique characteristics of the human brain that traditional animal models do. These include the so-called brain on a chip technologiesthat mimic brain tissue in devices the size of a credit card, and brain organoidswhich are simplified miniature models of brains that self-assemble in dishes.
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However, unlike organoids, the printing technique gives scientists more control over which cells end up where in the final tissue. Nerves within the printed tissue also form connections with each other within two to five weeks, a process that can take many months in organoids. Dr. Su-Chun ZhangCo-senior author of the study and professor of neuroscience and neurology at the University of Wisconsin-Madison, told Live Science in an email.
Thanks to this speed, different versions of 3D-printed brain tissue can also be made much more easily than organoids, Zhang said. Therefore, this technology could be particularly useful for testing new drug candidates for diseases that affect brain function, such as neurodegenerative and psychiatric disorders, she added. This is because different printed models could be designed to show the characteristics of each disorder.
Scientists have He previously attempted to print human brain tissue.. However, the neurons and glia within the final product were unable to form proper working connections with each other, the authors wrote in the paper. The new printing approach allowed networks to form because it used a gel that was soft enough to facilitate this process, allowing the cells enough flexibility to spread and connect. Additionally, the gel had the extra strength needed to hold the layers of brain tissue together.
And unlike traditional 3D printing methods, which stack layers of material vertically, the authors stacked their gel horizontally. This allowed the layers to be thinner and therefore the cells within them to be exposed to as much oxygen and nutrients as possible.
The printed stem cells became complete neurons and glia cells, which formed networks similar to those found in the human brain, and even communicated with each other. Through chemical messengers called neurotransmitters.. The printed cells that normally belong to different parts of the brain, such as its outer layer or cortex, and the striatumwho participates in decision making, also established connections with each other.
The new model still has flaws, the authors acknowledged. For example, the softness of the gel means that multiple layers cannot be printed at once, because they would collapse if the gel were not allowed to settle between them. This slows down the printing process. The individual layers are also limited in thickness due to the nutrient demands of the cells within them, consequently restricting the overall size of the tissue.
“A model is a model, not the real brain,” Zhang said. However, the team is working to address these potential obstacles and refine the technology in the future, she said.
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