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International Journal of Bioprinting 3D bioprinting in otorhinolaryngology

the physiological matrix, cell connections, and overall and organ repair. Lesmes et al. recently used polyglycolic
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contractility. The mechanical properties of agarose are acid (PGA) to print a scaffold to support cartilage growth
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similar to those of the tissue structures in the human body, and subcutaneous implantation. The chondrocyte-seeded
and it can be used as a standalone support material or PGA scaffolds, containing chondrocytes from children
provide mechanical stability for other soft gel materials to and rabbits, were transplanted into immunocompetent
support cell maturation, considering its easy removal after rabbits and successfully promoted cartilage growth to
maturation. 130,131 Finally, the viability of cells before and obtain sufficient full-size ear-shaped cartilage. A dense
after bioprinting is also a key consideration. Experiments type II collagen network and a small amount of type
have demonstrated that the proliferation rate of printed I collagen production were observed 2 months after
tissue structures was remarkable, suggesting that the cells transplantation. These results proved this approach can be
had good access to nutrients and the bioprinting process used to obtain a sufficient amount of cartilage for auricular
does not affect the survival rate of the encapsulated cells. reconstruction surgery. 135
Kang et al. printed hydrogel-loaded rabbit ear chondrocyte Kang et al. successfully printed a multi-material,
components supplemented with degradable biopolymers. patient-specific, human-scale, auricular cartilage scaffold
The simultaneous bioprinting of cell components and using (i) rabbit ear chondrocytes mixed with a composite
a temporary hydrogel mold resulted in a structurally hydrogel (containing gelatin, fibrinogen, hyaluronic acid,
stable post-scaffold that gradually dissolved to ensure the and glycerol) and (ii) PCL-thrombin-crosslinked Pluronic
diffusion of nutrients and oxygen into the printed tissue. F-127 hydrogel as a sacrificial external support layer.
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The designed scaffold had sufficient mechanical properties. The artificial ear retained its shape for 1–2 months after
Cell proliferation and differentiation in the scaffold transplantation into athymic mice, demonstrating the
displayed a high cell survival rate and produced new tissue feasibility of the approach. Simultaneously, the authors
structures with mechanical characteristics similar to those described the formation of microchannels from the
of natural auricular cartilage. The cell-loaded hydrogel composite to facilitate diffusion of nutrients and oxygen
protected the viability of the cells, and the temporary into the tissues, as well as the potential of this bioprinting
scaffold structure provided stability and integrity. However, method for the formation of various vascularized tissues.
during the transition from cells to tissue components, the This approach may restore the structure and function of
cells secreted a matrix that replaced the hydrogel scaffold. the tissues to their natural state and can be used in the
Nonetheless, this scaffold bioprinting method would be clinical setting.
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suitable for tissue engineering.
Numerous studies have evaluated the feasibility
5. Application of 3D bioprinting in otology of growing cartilage on human auricle-shaped
biomaterial scaffolds, but few have reported on human
5.1. Auricle reconstruction transplantation. Zhou et al. printed (i) ear scaffolds
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External ear diseases, such as microtia, often have for pediatric deformity patients and (ii) a 3D scaffold
negative physical (i.e., dysfunction) and psychological of microtia chondrocytes (from skin expansion) for
(i.e., appearance) effects and usually require surgical implantation in vivo. Satisfactory aesthetic results and
reconstruction. 132 Prosthetic reconstruction and mature cartilage formation were achieved at the 30-month
autologous cartilage transplantation are commonly used follow-up (Figure 5A). Wang et al. studied 20 cases of
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in external ear reconstruction, but not without their microtia reconstruction using customized 3D-printed ear
respective limitations. For example, the prosthesis models and reported relatively high accuracy and good
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may be extruded, and the autograft may cause lesions at reconstruction results with few complications. Whole
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the donor site or be limited by size. In recent years, 3D ear autotransplantation can also be completed by inserting
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bioprinting has displayed obvious advantages that could a cartilage framework into the free flap of the anterior wall
circumvent the complications of reconstruction surgery of the radius and then transplanting it to the head and
with autologous transplantation for better reconstruction neck. The auricular framework can be constructed using
results.
3D bioprinting and implanted into a radial forearm free
The basis of auricle reconstruction lies in bioprinting flap to assist in the recovery of patients with complete
cartilage scaffolds. Numerous studies have reported amputation of the right ear (Figure 5B).
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the construction of auricle cartilage scaffolds using 3D
bioprinting. These scaffolds are to be loaded with cells 5.2. Middle ear reconstruction
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to support the directional differentiation of living cells Several types of middle ear diseases, such as chronic
into mature cells with distinct functions and subsequently suppurative otitis media and otosclerosis, can cause
incorporated into an extracellular matrix to promote tissue conductive deafness. In these circumstances, the ossicle is

Volume 10 Issue 4 (2024) 40 doi: 10.36922/ijb.3006