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Zhang, et al.
to cure. Recently, the artificial spinal cord shows miniscule structure, such as liver, lung and other
great potential in assisting SCI repair [54,62,63] . vascularized tissues.
The 3D printing technology allows the
fabrication of personalized scaffolds that are 5 Pharmacy
matched with the patients’ injured sites. The The 3D printing technology can be used in all
microstructure can promote SCI repair by phases of pharmacy research, including drug
stimulating, guiding, and aligning axon. However, discovery, development, and delivery . Despite
[66]
due to the complex inner structure of the spinal the continuous improvement of detection
cord, it is difficult to construct a spinal cord equipment and technology, achievement in
structure in detail . The technology of DLP 3D discovery and development require a long time
[62]
printing provides a method to manufacture such and high cost, which are mainly reflected in
complex and precise structures. Using this rapid screening drugs from a large number of candidates
3D printing technology, Koffler et al. printed 3D and researching their absorption, metabolization,
biomimetic hydrogel scaffolds suitable for rodent toxicity, etc. As described in the previous section,
spinal cord size in several seconds (Figure 3E) .
[54]
The printed scaffolds can encapsulate the neuronal the DLP 3D printed tissue or organ or disease
progenitor cells (NPCs) and promote axonal model can simulate the real situation of human
regeneration. After implanting the bionic scaffold body. It can be used to discover and develop drugs
[42]
to replace the injured site, the damaged axons in vitro and replace part animal experiments .
regenerated and entered to the scaffold and High-accuracy 3D printing allows the fabrication
synapsed with NPCs. The NPCs extended to and of pharmaceutical preparations with fine
synapsed with the host spinal cord below the structures, and control the position and dose of
injury. The scaffold formed a new “contact” across drugs precisely.
the entire spinal cord and improved the recovery 5.1 Drug discovery and development
of the function of spinal cord. The artificial spinal
cord tissue can be extended to human spinal cord In the early stage of drug development, 3D
size and fit to any shapes. printing products have important applications
The 3D bioprinting has been widely used in in early and high throughput drug screening
fabricating various tissues and organs. Inkjet and due to their complex bionic structure and good
[67]
extrusion bioprinters are good methods to solve part repeatability . It is difficult to get a satisfying
of the problems in tissue engineering. However, result by applying traditional 2D and 3D disease
these two methods also have limitations. First, models for drug screening. These disease models
they are nozzle-based 3D printing technology. lack bionic structures, vascular networks, and
Due to the small aperture of the nozzle, used to complex microenvironments. In the section of
deliver bio-ink, cells will be stressed and damaged tissue engineering, it has been discussed that
during passing through the nozzle. Next, the DLP-based 3D printing can build complicated
printing resolution is limited by the aperture of vascularized tissues, which can also be used in
the nozzle, which is usually bigger than 50 μm. fabricating disease models correspond to those in
Finally, the printing speed of these methods is not the human body. If these models were applied in
very high. Cells would subside to the bottom of the drug screening, the results might be more accurate.
printing ink in the process of printing [16,64,65] . DLP On the cover glass, an alginate loaded gel chip
3D bioprinting is a rapid, precise and mild printing loaded with Escherichia coli was printed on the
method. The printing speed is approximately cover glass as a platform for high-throughput
~1000× times faster than the traditional nozzle screening of micro drugs . Three drops of
[68]
printers . The X- and Y-resolutions can reach the antibiotic mixture (penicillin/streptomycin,
[16]
6 μm. Thus, DLP 3D bioprinting has advantages antifungal agent, and kanamycin sulfate) were
in fabricating living tissues with complex and added to evaluate the bioactivity, function,

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