Correction to: Effects of astrocyte on neuronal outgrowth in a layered 3D structure.

It was highlighted that the original article [1] contained an error in the Acknowledgments section.

Effects of astrocyte on neuronal outgrowth in a layered 3D structure.

BACKGROUND: Human brain models and pharmacological models of brain diseases are in high demand for drug screening because animal models have been found to be less than ideal for fully representing the human brain and are likely to fail during drug screening and testing; therefore, the construction of brain-like tissues is necessary. Due to the complexity of cortical tissue, the in vitro construction of brain-like tissue models has been restricted to mostly two-dimensional (2D) models and, on a limited scale, three-dimensional (3D) models. METHODS: In this study, 3D tissue blocks encapsulating neurons and astrocytes were constructed and cultured in vitro to mimic the cortex of the brain and to investigate the effects of astrocytes on the growth of neurons in a 3D culture. RESULTS: The results indicated that such methodology can provide a 3D culture environment suitable for neurons and astrocytes to live and function. When both cells were evenly mixed and cultured in a 3D manner, the astrocytes, which showed better outgrowth and a higher proliferation rate, benefited more than the neurons. On the other hand, the neurons benefited, showing longer axons and a denser network of dendrites, when they were accompanied by astrocytes at a certain distance. CONCLUSION: In conclusion, astrocytes stimulated the outgrowth of neurons in a 3D culture environment in vitro. Regardless, the spatial relationship between both types of cells should be controlled. Thus, culturing cells in a 3D manner is necessary to investigate the correlations between them. This study provides a foundation for biofabricating 3D neurons' cultures to allow for a deeper insight into the relationship between astrocytes or other glial cells and neurons in a 3D culture that is similar to the natural environment of the brain.

3D Printing of Layered Gradient Pore Structure of Brain-like Tissue.

The pathological research and drug development of brain diseases require appropriate brain models. Given the complex, layered structure of the cerebral cortex, as well as the constraints on the medical ethics and the inaccuracy of animal models, it is necessary to construct a brain-like model in vitro. In this study, we designed and built integrated three-dimensional (3D) printing equipment for cell printing/culture, which can guarantee cell viability in the printing process and provide the equipment foundation for manufacturing the layered structures with gradient distribution of pore size. Based on this printing equipment, to achieve the purpose of printing the layered structures with multiple materials, we conducted research on the performance of bio-inks with different compositions and optimized the printing process. By extruding and stacking materials, we can print the layered structure with the uniform distribution of cells and the gradient distribution of pore sizes. Finally, we can accurately print a structure with 30 layers. The line width (resolution) of the printed monolayer structure was about 478 mm, the forming accuracy can reach 97.24%, and the viability of cells in the printed structure is as high as 94.5%.