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International Journal of Bioprinting 3D printing technology in neurotrauma

are compatible with a variety of materials, capable of 2. Three-dimensional printing technologies
creating constructs with high resolution and highly for neurotrauma treatment
controllable spatial structures. It allows customization
according to the characteristics of different diseases. 32-34 The 3D printing technologies currently used for
3D bioprinting is an extended application of the neurotrauma treatment can be divided into two categories.
additive manufacturing process or rapid prototyping The first category is cell-free printing, like fused deposition
(RP) systems to print various cells, bioactive substances, modeling, near-field electrospinning, and two-photon
and biomaterials in the form of layers, which can printing. This type of 3D printing technology usually
produce biological constructs that highly mimic the requires high temperatures, lasers, and other cell-harmful
properties of innate tissues and organs. Bioink is environments. Such printed constructs usually exploit
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an important component in bioprinting. Bioinks are their physical properties or are used to carry drugs to treat
composed of biomaterials that encapsulate cells or neurotrauma. The other type is bioprinting, which uses
bioactive substances, allowing the creation of mimetic bioink to directly print constructs, like inkjet, extrusion,
3D tissue constructs by different printing principles stereolithography, and digital light processing. This type of
such as extrusion, inkjet, stereolithography, and digital 3D printing technology enables more accurate arrangement
light processing. 36 of cells, bioactive components, and biomaterials, thereby
better simulating the microenvironment for repairing
1.4. Advantages of 3D printing in neurotrauma nervous system injuries. The principles, advantages, and
3D printing technology has many unique advantages in disadvantages of various 3D printing methods used for
treating neurotrauma. First, 3D printing can customize neurotrauma treatment are summarized in Figure 1 and
personalized constructs based on different nervous Table 1, respectively.
system injuries. Constructs designed based on 3D
topological data of patients using 3D imaging technology 2.1. 3D printing technology
are highly matched to the patient’s injured site, facilitating 2.1.1. Fused deposition modeling
nerve regeneration and neurological function recovery. Fused deposition modeling (FDM) is a 3D printing
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Secondly, 3D printing can directly print cells and technique based on the controlled, layer-by-layer deposition
bioactive substances by various bioinks at precise and of thermoplastic materials. FDM printing process involves
optimal locations, such as in specific areas of a layered heating a filament of thermoplastic material until it
or multi-channel scaffold, to better facilitate the survival becomes molten and extruding it through a fine nozzle
of transplanted cells and nerve regeneration. Thirdly, onto a build platform. The material quickly solidifies,
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the nervous system is composed of complex cells and forming a layer, and the platform is lowered for the next
ECM components. 3D printing allows different types of layer. The process is repeated until the entire 3D structure
cells (e.g., nerve cells, glial cells, and immune cells) and is fabricated. FDM is well-suited for material fabrication
different bioactive substances (e.g., neurotrophic factors and the production of highly porous constructs and fully
and cytokines) to be combined with various biomaterials interconnected channel networks. 41,42 It enables localized
and printed simultaneously to better restore the neural and targeted drug delivery within the nervous system,
microenvironment of the injured site. 38,39 Finally, the reducing systemic side effects and optimizing treatment
nervous system is fragile and mainly located within effectiveness. One of the primary applications of FDM
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bony structures, making it difficult to be accessible in the field of regeneration medicine is the fabrication of
for examination. 3D printing enables long-term, non- constructs with porous structures and controllable pore
invasive visualization of implanted constructs by adding sizes, into which cells can be seeded to repair injured
contrast agents to bioinks. tissue. Channels and cavities within the constructs can
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Herein, we introduce 3D printing and bioprinting facilitate nutrient and oxygen exchange for growing cells.
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technologies based on different principles that have been Besides, the 3D construct with gaps obtained through FDM
applied to neurotrauma treatment, and summarize the makes it easier to induce cells to differentiate into neural
current strategies in the aspects of biomaterials, physical cells. However, the disadvantages of FDM include poor
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stimulation, bioactive substances, cell transplantation, mechanical properties, limited availability of thermoplastic
and their combination that have been considered in polymers, substandard surface properties, and the inability
the fabrication of 3D-printed devices for neurotrauma to directly print cells. The layer-by-layer construction in
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treatment. Finally, the challenges and prospects FDM may result in visible layer lines on the final construct,
of combining 3D printing to treat neurotrauma potentially affecting biocompatibility and surface quality.
are discussed. FDM typically offers lower resolution than high-precision

Volume 10 Issue 3 (2024) 63 doi: 10.36922/ijb.2311