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International Journal of Bioprinting 3D bioprinting in otorhinolaryngology

organoid model could potentially be constructed soon patient with congenital tracheoesophageal fistula and
using 3D bioprinting. reported prolonged patient survival (Figure 10B). Yu
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et al. designed a 3D-printed absorbable airway external
7.2.2. Trachea fixator for the treatment of patients with congenital heart
Airway stenosis is a common laryngeal and neck disease disease and severe airway disease. The splint effectively
that results in severe dyspnea and is treated with airway limited external pressure, prevented airway collapse,
reconstruction. In the diagnosis and treatment of tracheal and prevented airway growth. Consequently, respiratory
stenosis, 3D bioprinting is an effective auxiliary diagnosis symptoms were relieved in an experiment involving
and treatment method. Before surgery, 3D bioprinting can nine patients, and there were no related complications.
accurately restore the narrow plane and angle to guide the These findings highlight the safety and reliability of 3D
surgery for relieving the obstruction. Reighard et al. used bioprinting in treating trachea-related conditions. 199
a combination of computer-aided design (CAD) and 3D
bioprinting to produce a low-cost, high-fidelity surgical In conclusion, 3D bioprinting has been clinically
simulation model for the laryngotracheal reconstruction applied for tracheal surgery reconstruction. In the future,
of subglottic stenosis. Jackson et al. used 3D bioprinting there must be more technologies for better manufacture
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to model the tracheal stenosis of two children and used the of bioprinted trachea to achieve better reconstruction of
model to guide the tracheal reconstruction surgery. related nonregenerative tissues.
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Tracheal stenosis, caused by malignant tumors, requires 7.2.3. Vocal fold
tracheal resection according to the extent of invasion. Recently, voice-related research (e.g., production, disorders,
Consequently, the defective trachea needs to be repaired. and learning) has received increasing attention, with a
The trachea is a complex and heterogeneous structure particular focus on vocal fold vibrations. Human vocal
consisting of alternating C-shaped cartilage (C-C) rings and folds (VFs) comprise different types of tissues with large
connected vascularized fibrous tissue (VF) rings, as well variations in stiffness and vibrate due to airflow in and out
as the endovascular epithelium. Because of the complex of the lungs. In vocal fold research, synthetic experiment
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anatomy of the trachea, the application of 3D bioprinting models are easier to obtain than in vivo experiment models,
is still difficult, and many conditions need to be met, except for laryngectomy. The use of 3D bioprinting can
including efficient and inexpensive bioprinting methods, accurately restore the structure and movements of the
adequate mechanical strength and structural stability, and vocal fold. Romero et al. used liquid silica gel bioink and
tissue-specific growth. Numerous studies have proposed printed self-oscillating synthetic vocal fold structures
design methods for manufacturing 3D-printed tissues for by layer-by-layer extrusion in the supporting matrix
tracheal anastomosis. Sun et al. reported a C-shaped bionic through a translation needle. Compared with conventional
trachea using 3D bioprinting. In their design, GelMA was manufacturing methods, this method is low-cost and rapid.
first crosslinked with chondroitin sulfate methacryloyl The synthetic vocal fold models could self-oscillate at
(CSMA) as a cartilage-specific matrix gel and elastin frequencies and amplitudes similar to a regular human vocal
methacryloyl (ElaMA) as a fibrous tissue-specific matrix fold. Greenwood et al. used embedded 3D bioprinting
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gel using a hybrid photocrosslinking strategy. The two to fabricate vocal fold models comprising four layers: (i)
types of hydrogels were printed as C-type trachea rings, body, (ii) ligament, (iii) superficial lamina propria, and (iv)
and the rabbit trachea was reconstructed by end-to-end the epithelium and fibers within the ligament layer. These
anastomosis. The printed tissue (even after 8 weeks structures simulate the geometry, stiffness, and directional
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after implantation) displayed good mechanical properties motion of the vocal folds. Although the resulting structures
capable of supporting tracheal reconstruction, with mature may be slightly different from human vocal cords, they
fibrous tissue formation, epithelial tissue formation, are comparable and better than the models generated
and abundant vascular infiltration. The results of this using other technologies. While the inner geometry of the
study demonstrated the potential of bionic trachea as an synthetic vocal folds may be limited by the spatial resolution
alternative therapy for the repair of segmental duct defects, of the printer, further research and refinements could
warranting further research prior to clinical application. facilitate the development of more detailed structures with
accurate restoration of each layer.
In addition, several clinical studies have demonstrated
the value of 3D bioprinting in tracheal applications, and the 8. Conclusion
successful construction of 3D trachea has been confirmed
in in vivo and in vitro studies (Figure 10A and C). 195-197 Tsai In this review, we described the latest application of
et al. treated tracheal loss via esophageal reconstruction 3D bioprinting in otorhinolaryngology. 3D bioprinting
with a 3D-printed absorbable PCL tracheal splint in a is an emerging and rapidly developing manufacturing

Volume 10 Issue 4 (2024) 49 doi: 10.36922/ijb.3006