3D-Printing Neural Networks: A Step Forward in Biomedical Research

In a remarkable feat of scientific innovation, researchers at Monash University in Melbourne, Australia, have successfully 3D-printed living neural networks composed of rat brain cells. This breakthrough has profound implications for the future of drug trials and the study of brain functions.

“We’re inching our way closer to doing experiments that don’t require animals in the most complex organ we know of. Perhaps the most complex structure in the universe.” - Michael Moore, Professor of Biomedical Engineering at Tulane University.

Why 3D-Print Neural Networks?

The creation of mini-brains is driven partially by the desire to find an alternative to animal testing in drug trials and studies of basic brain function. In 2023, the US Congress passed a spending bill urging scientists to reduce their use of animals in federally funded research. This followed the US Food and Drug Administration’s Modernization Act 2.0, which permitted high-tech alternatives in drug safety trials. In theory, pharmaceutical companies could apply new drugs to 3D-printed mini-brains instead of testing them on animals. However, significant complexities must be resolved before this becomes a standard lab practice.

3D-Printing: A Promising Technique

3D printing offers a promising method for the development of a better mini-brain. While existing options involve culturing a layer of neurons in a petri dish or coaxing stem cells to organize themselves into 3D tissues called organoids, 3D printing provides a unique advantage. Researchers can use this technique to culture cells in specific patterns on top of recording electrodes, allowing for experimental control. The structure is also soft enough to enable cells to migrate and reorganize themselves in 3D space, more closely mimicking the form of normal tissue.

Creating Neural Structures with 3D-Printing

The team at Monash University, led by materials science and engineering professor John Forsythe, described their experiment in the journal Advanced Healthcare Materials. They created their neural networks by 3D-printing "bioink" - rat brain cells suspended in a gel - into a scaffold. They constructed the networks by crosshatching layer by layer, creating a structure that gave cells access to nutrients while mimicking the alternating grey and white matter in the cortex. As they matured, the 3D-printed neurons extended their long axons across cell-free layers to reach other cells, enabling them to communicate across layers like in the cortex.

Implications and Future Work

This breakthrough has significant implications for biomedical applications like drug discovery and the study of neurodegenerative diseases. However, for these neural networks to be valuable, they need to be functional, which involves ensuring the survival of the cells during the printing process. Researchers also need to replicate this level of function in human cells before these neural network models can be used in translational research and medicine. Furthermore, the technique could be faster, and scaling from academic research labs to pharmaceutical companies will be challenging.

Despite these obstacles, the 3D printing of neural networks shows excellent promise for the future. It could eventually replace animals in many research settings and even lead to the creation of living artificial neural networks. This technology could be used for personalized treatments for neurodegenerative diseases and other brain injuries, pushing the boundaries of personalized medicine.