Scientists have been creating brain “organoids” for years, but tiny lab-grown cultures have their limits. One of the most frustrating problems is the lack of control over their design, which often limits the functionality and use of an organoid. Although researchers have long suspected that 3D printing could offer a solution, the workaround has so far proven difficult and ineffective. A new breakthrough in production, however, could resolve this long-standing hurdle and one day provide new avenues for exploring the treatment of diseases such as Parkinson's and Alzheimer's.
As detailed in the new issue of the journal Stem cell, researchers at the University of Wisconsin-Madison have developed a new 3D printing approach to create cultures that grow and function similarly to brain tissue. While traditional 3D printing involves layering “bio-ink” vertically like a cake, the team instead instructed their machine to print horizontally, as if playing dominoes.
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As New Atlas explain, researchers placed neurons cultured from pluripotent stem cells (capable of becoming several different types of cells) in a new bio-ink gel based on fibrinogen and thrombin, biomaterials involved in blood clotting. The addition of other hydrogels then made it possible to detach the bio-ink to resolve the 3 problems encountered in previous experiments on 3D printed fabrics.
According to Su-Chun Zhang, research director and professor of neuroscience and neurology at UW-Madison, the resulting tissue is strong enough to maintain its structure, but also malleable enough to allow neurons to absorb adequate levels of oxygen and nutrients.
“The tissue still has enough structure to hold together, but it is soft enough to allow neurons to grow into each other and start communicating with each other,” Zhang explains in a paper. recent academic profile.
Because of their horizontal construction, the new tissue cells formed connections not only within each layer, but also between them, much like human neurons. The new structures could interact through the production of neurotransmitters and even create networks of supporting cells within 3D printed tissues.
In these experiments, the team printed cultures of cerebral cortex and striatum. Although responsible for very different functions – the former associated with thought, language and voluntary movement; the latter being linked to visual information – the two 3D printed fabrics could still communicate, “in a very special and specific way”, Zhang said.
The researchers believe their technique is not limited to creating just these two types of cultures, but hypothetically “just about any type of neuron.” [sic] at any time,” according to Zhang. This means that the 3D printing method could eventually help study how healthy parts of the brain interact with parts affected by Alzheimer's disease, examining cellular signal pathways in Down syndrome, as well as to use tissues to test new drugs.
“Our brain works in networks,” Zhang explained. “We want to print brain tissue this way because cells don't work on their own. They are talking to each other. This is how our brain works and we need to study it together to truly understand it.