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Pei, et al.
According to the layered characteristics of the brain Fundamental Research Funds for the Central Universities,
tissue, in this paper, we developed a technology to print and the Youth Innovation Team of Shaanxi Universities.
the layered structure with gradient distribution of pore
size. This technology not only be used to manufacture Conflicts of interest
brain-like tissue with layered structure, but also can We have no financial and personal relationships with other
be used to manufacture layered tissues widely existing people or organizations that can inappropriately influence
in human body, such as cartilage, blood vessels and our work, there is no professional or other personal
others. By changing and optimizing the cell type and cell interest of any nature or kind in any product, service, and/
density used in this printing process, we can construct the or company that could be construed as influencing the
corresponding tissue/organ in vitro. position presented in, or the review of, this article.
We encountered some problems in this study.
A printed structure of <30 layers can maintain a more Author contributions
regular and complete structure, but when the printed
structure had more than 30 layers, the edge of the printed J.H. is one of the guest editors of the Special Issue:
structure began to appear defects, but the middle part Bioprinting of 3D Functional Tissue Constructs. The
could still maintain a better structure. In future research, editorial and peer-review processes of this paper was
we plan to further optimize the printing parameters and exclusively handled by the editors of the journal without
printing process to produce a structure with more layers. interference of any of the guest editors.
Although the cells possess a high survival rate and References
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Acknowledgments Perspectives in Extrusion-based Bioprinting. Biomaterials,

The work was supported by the Program of the National 76:321–43.
Natural Science Foundation of China (51675411), and the https://doi.org/10.1016/j.biomaterials.2015.10.076

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