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International Journal of Bioprinting 3D bioprinting in otorhinolaryngology

in PU microspheres, was printed at low temperatures to Their results demonstrated that chondrogenic bMSCs had
form scaffolds containing Y27632 microspheres, and a greater potential for new cartilage formation in the short
mesenchymal stem cells (MSCs) in the scaffolds were term. However, viral transduction is necessary during the
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observed to migrate and differentiate in vitro. Moreover, differentiation and proliferation of iPSCs and may have its
the in vivo experiments revealed that the stent promoted potential risks. For example, stem cells may be susceptible
cartilage cell regeneration. Tallia et al. and Li et al. used to insertional mutations, tumorigenesis, and teratoma
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an inorganic–organic hybrid of SiO -polytetrahydrofuran/ formation. Regardless, stem cells are not ideal bioinks
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2
PCL as a bioink to fabricate a regenerative scaffold for due to their poor repeatability, incomplete differentiation,
cartilage using 3D bioprinting. The printed silicone low quantity, and low usage, thereby warranting further
network and organic components were combined using research to enhance cell differentiation and proliferation
covalent bonds, both of which have similar elasticity, self- for better application in bioprinting technology. Liang et
healing ability, and biological activity when used in vivo al. developed a new extrusion-based bioprinting method
as tissues. Cartilage differentiation was observed during with pre-cultured MSCs in hydrogels, supplemented with
in vitro experiments. In addition, Park et al. used PCL to alginate–gelatin–collagen, for use as a cellular aggregating
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print porous bellows framework and STP mesh. Moreover, bioink in bioprinting. The resultant bioink displayed
hNCs and hNTSCs were encapsulated in thermosensitive enhanced differentiation and proliferation as compared
3% (w/v) atelocollagen-based hydrogel to print trachea with single-cell bioinks, demonstrating the potential for
rings and epithelium, thereby producing trachea structures complex tissue construction. 104
(Figure 4B). 96 Different mature cell types can be used as bioinks

3.5. Cells for different structures, depending on the tissue source.
The cell source used in 3D bioprinting often depends For example, Gantumur et al. successfully constructed a
on the anatomy and function of the target tissue. In human nasal-like 3D construct from a bioink formulation
otorhinolaryngology, cells are divided into stem and containing mouse 10T1/2 fibroblasts using extrusion-based
mature cells according to their degree of differentiation and bioprinting, and the cells of the 3D construct displayed
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can be used as bioinks alone for bioprinting or combined excellent stability in vitro. The success of cell formulations
with other biomaterials. Stem cells, such as embryonic has helped to promote 3D bioprinting for the direct
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stem cells (ESCs), induced pluripotent stem cells (iPSCs), construction of living tissues, highlighting a significant
human amniotic fluid stem cells (hAFSCs), and MSCs, breakthrough in the history of 3D bioprinting. Although
are often subjected to targeted differentiation to obtain there is a lack of direct application of cell bioinks in clinical
bone, cartilage, and other tissue types for use as bioink implantation, cell bioinks have reported good proliferation
components. 85,97-99 For example, human ESC (hESC)- and differentiation in vivo, and these bioink formulations
derived oral neuron progenitor cells (ONPs) were cultured can potentially stimulate artificial regeneration and solve
in a hypoxic environment to aggregate into multicellular common clinical problems related to tissue repair (e.g.,
spheres, a polymeric form that facilitates differentiation, poor cellular regeneration), such as in tracheal cartilages
transplantation, and prolonged cell survival to optimize and nerves that become permanently dysfunctional
their transplantation conditions. The bioprinting of upon damage. Current studies use two main methods to
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inner ear structures using a bioink developed with cell stimulate artificial regeneration: (i) induce different stem
spheres may be an alternative to cochlear implants for cell types to proliferate and differentiate into target tissues,
treating sensory hearing loss. Adipose-derived stem and (ii) use the regenerative ability of the original tissue in
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cells (ADSCs) have become one of the most popular seed vitro to restore tissue function. These methods have their
cells used in 3D cartilage bioprinting because of their respective advantages and disadvantages. For stem cells,
high quantity, good proliferative potential, low harvest it is necessary to limit differentiation and proliferation to
incidence, and ethical advantages. Researchers can prevent tumor formation, but mature cells should have
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induce ADSC differentiation to form different cartilage rapid regenerative abilities. Therefore, future studies
tissues and construct different bioinks with the addition should focus on developing better methods to improve the
of appropriate growth factors and stimulating forces. In efficiency and outcome of tissue repair.
one study, researchers designed hydrogel bioinks loaded
with human ADSCs that exhibited reasonable printability 4. Bioink performance
and successful differentiation into osteoblasts. Bae et An ideal bioink should share similar physical and
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al. printed a trachea structure by culturing rabbit bone chemical properties (printability, mechanical properties,
marrow MSCs (bMSCs) and respiratory epithelial cells biodegradability, biocompatibility, and biological activity)
and subsequently differentiated them in different media. to the structure of interest to ensure that the bioprinted

Volume 10 Issue 4 (2024) 37 doi: 10.36922/ijb.3006