Bioprinting Technology: Overview, Applications, and Challenges

This report provides a comprehensive introduction to bioprinting technology, a revolutionary field in regenerative medicine. It begins by highlighting the critical need for organ transplants and how bioprinting offers a promising solution. The report then delves into the bioprinting process, explaining the use of bio-inks and 3D models to create structures that mimic natural tissues. Key bioprinters, including the EnvisionTEC 3D-Bioplotter, RegenHu 3DDiscovery Evolution, and Poietis NGB-R & NGB-C printers, are compared and contrasted based on their technology, resolution, and materials used. The report also addresses the challenges faced by the bioprinting industry, such as limitations in materials, cell sources, and vascularization. The application of bioprinting in kidney creation is discussed, including the necessary steps and testing procedures. Finally, the report highlights the importance of material properties and strategies to overcome cell apoptosis during the printing process, concluding with a forward-looking perspective on the future of bioprinting in organ transplantation and improved healthcare outcomes.

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Bioprinting Technology
Introduction
The shortage of organs is a major concern for most health care providers across the
globe. Advance in medical technology has raised the quality of life of most people thus
longer lifespans (Giwa et al., 2017). Since the number of available transplants has not gone
up to meet the demand, bioprinting or regenerative medicine comes in to fill the void. Bio-
printing is a manufacturing process whereby biomaterials for instance hydrogels are
combined with growth factors and cells and printed into structures that mimic natural tissues
(Sundaramurthi et al., 2016). The bioprinting process is based on digital models that the
printer produces. Bio ink is the material that is used to manufacture the organs in a layer to
layer manner. Post-bioprinting is done to check the chemical and mechanical stable structures
for the actual biological material. In this paper, we will compare and contrast some of the
available bioprinting technologies and challenges faced. Kidney bioprinting provides an
exciting alternative for donors in transplantation.
Bioprinters
EnvisionTEC 3D-Bioplotter is a 3D bioprinter that was commercialized by the
EnvisionTec company. The printer is extrusion-based and can hold up to five print heads.
This bioprinter has a resolution of 0.001mm and can make scaffolds from several materials
including medical-grade silicone and thermoplastics. The printer can use cells ranging from
pluripotent stem cells among others. comes in three versions based on the required
application (Envision, T.E.C, 2013).

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RegenHu 3DDiscovery Evolution is a bioprinter developed by the RegenHu company
based in Switzerland. Like the EnivsionTec it is extrusion-based and capable of handling
multiple print heads. The printer is more cost-effective compared to the EnvisionTEC. The
materials it uses include hyaluronic acid-based, gelatin and PEG for bio-ink and calcium
phosphate for Osteoink. RegenHu resolution is +(-)5 μm (Ozbolat, 2017).
The next bioprinters are the Poietis NGB-R & NGB-C printers from the Poietis
company. Unlike EnvisionTEC and RegenHu, NGB-R and NGB-C use the latest technology
for bioprinting. The printer uses tiny laser pulses shot that deposit small droplets of bio-ink
every nanosecond which contrasts the EnvisionTEC and RegenHu that use print heads. The
printer is a laser-assisted type of computer which is different from the previous two. The
printers have a high resolution of nanometres because they are laser-guided (Guillemot et al.,
2018).
Challenges facing Bioprinting
Bioprinting faces several challenges. Bioprinting technology limits the
commercialization of the printers. Technology such as speed and resolution enables better
control and interaction in the 3D environment. The limited availability of biocompatible
synthetic materials and bio-inks reduces the applications of bioprinting. Another major
challenge facing the bioprinting industry is the choice of cell sources which determines the
success of the printed construct. The way the cells such as stem-cells interact with the
scaffold and their differentiation is essential for successful printing. Another challenge facing
the industry is the vasculature of the final printed construct. In-vivo tissues are constantly
supplied with nutrients and oxygen through several vessels. In-vitro tissues, therefore, need to
mimic this aspect in every way which is always not easy (Malkoc, 2018).

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Kidney Bioprinting and Testing
A kidney can be printed by following three major steps essential in bio-printing. The
first step is the development of a blueprint that is used to give a digital reconstruction of a
live kidney. The next step is layer by layer printing whereby the printing bioink materials and
cells are placed into the scaffold using means such as stereolithography. The last step is post-
organ processing whereby the printed kidney matures and perfused. Kidneys have a complex
structure with about 26 different cell types that are derived from the metanephrogenic
mesenchyme and ureteric buds (Destefani et al., 2017). Therefore, autologous cells are
generated from stem cells and biopsies. Embryonic stem cells can also be used but are limited
by ethical concern. Important tests performed before transplanting include HLA typing
ensures that the organ won’t be rejected (Wragg et al., 2019). Other tests include structural
and functional viability of the organ.
Key materials properties to test before printing
Before bioprinting, the printing materials must be tested for properties such as
cytocompatibility, printability, bioactivity, degradation, functionalization capacity, mechanics
and biocompatibility (Ji and Guvendiren, 2017). If the biomaterials are not tested, they risk
being attacked by the host’s immune system.
Ways to overcome cell apoptosis during printing.
Bioprinting consists of simultaneous deposition of biomaterial, growth factors and
cells under pressure. During this process cell, necrosis and apoptosis might occur. Reducing
the pressure with which cells are deposited may reduce cell death. One study showed that cell
death is significant when placed in hypotonic alginate before printing. Preparation of the
alginate in complete culture media or an isotonic solution such as phosphate-buffered saline
increases cell viability to 80%.

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Conclusion
Bioprinting is the future of organ transplants. If the technology is commercialized
then most lives will be saved thus improving the lifespan of human beings. Kidney failure
which is a major cause of mortality, especially during transplantation, can be curbed using
bioprinting technology.

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References
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Envision, T.E.C., 2013. 3D-Bioplotter. Envision TEC Technical Data, p.1.
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Ozbolat, I.T., Moncal, K.K. and Gudapati, H., 2017. Evaluation of bioprinter technologies.
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Sundaramurthi, D., Rauf, S. and Hauser, C., 2016. 3D bioprinting technology for regenerative
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Wragg, N.M., Burke, L. and Wilson, S.L., 2019. A critical review of current progress in 3D
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