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International Journal of Bioprinting Bioprinting hearing loss treatment

(nearly identical in terms of cartilage components, conducting polymers, enabling enhanced functionalities
toughness, and maturation), potentially addressing such as radiofrequency communication and music
the drawbacks associated with conventional auricular playback. Chen et al. pioneered a novel digital near-
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implants. 34,35 Ideally, bioprinted auricles are engineered infrared (NIR) photopolymerization (DNP)-based 3D
using combinations of hydrogel scaffold materials, a printing method, enabling 3D bioprinting in situ without
variety of other scaffold materials, and ear chondrocytes, causing trauma to implantation sites. Their research
without the distress of wound contraction and scar showcased promising advancements in the field of
formation. 36–39 The main process includes gathering data auricular cartilage implantation in animal models. In
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from the middle ear, external auditory canal, inner ear, and their 2021 study, Della Volpe et al. successfully replicated
facial morphology, followed by a combination of imaging the malformed temporal bone of a 5-year-old girl with
data collection and facial scanning to facilitate model tragus atresia in order to optimize the placement of a bone-
design and the subsequent 3D bioprinting of the external anchored hearing implant. The patient did not experience
ear. Lee et al. detailed the production of a personalized any adverse events during or after the procedure and
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ear-shaped 3D scaffold in early development utilizing achieved significant improvement in hearing. These
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a structural framework of polycaprolactone (PLA) and findings highlight the continuous advancement of 3D
alginate hydrogels encapsulating cells. A notable feature bioprinting technologies, as illustrated in Figure 2, which
of this study is the application of a multi-head tissue/ indicate that the management of anotia/microtia may
organ building system, which utilizes a multicellular progress towards more established methods with the aid of
3D printing method to allocate two distinct cell types, future technological innovations.
chondrocytes and adipocytes, derived from fat-stromal
cells for the regeneration of auricular cartilage and 2.2. Tympanic membrane perforation
the earlobe, respectively, as validated through in vitro Tympanic membrane perforations are a common
immunostaining. Zhou et al. developed a patient-specific occurrence in the field of otolaryngology. Although
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resin model of a healthy ear and a composite poly(glycolic minor perforations may resolve on their own, persistent
acid)/polylactic acid (PGA/PLA) coating scaffold with a perforations can result in chronic otitis media, conductive
polycaprolactone (PCL) core for auricular reconstruction. hearing loss, tinnitus, and the potential development
Following the process of trimming based on the ear of middle ear cholesteatoma over an extended period of
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resin model, implantation of auricular chondrocytes, time. Presently, autologous fascia remains the primary
and in vitro culturing, the desired auricular scaffold was material used for repairing tympanic membrane defects.
acquired and chosen for auricular reconstruction via The successful restoration of the tympanic membrane
skin flap expansion. Subsequent follow-up after 2.5 years necessitates careful evaluation of various factors, including
revealed that one out of the five patients with microtia and esthetics, safety, efficacy, cost, and efficiency. Currently,
other ear malformations expressed satisfaction with the the multipotent mesenchymal stem cells (MSCs) provide
reengineered ear morphology, and histological analysis a promising therapeutic approach for TMP due to their
indicated the presence of typical cartilage formation self-renewal capabilities and autocrine and paracrine
exhibiting properties akin to native auricular cartilage. functions. The regeneration of TMP can be achieved
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Kang et al. presented the integrated tissue-organ printer by administering MSCs either alone or combined with
(ITOP) as a sophisticated 3D bioprinting apparatus. The biomaterials and growth factors at the site of the damaged
researchers utilized Pluronic F-127 hydrogels as a sacrificial tympanic membrane. 47
layer to fabricate composite hydrogels containing rabbit A crucial element of TMP bioprinting entails the
ear chondrocytes (consisting of glycerol, hyaluronic acid, utilization of scaffolds that integrate cells with epidermal
gelatin, and fibrinogen) in conjunction with PCL. These growth factors to promote cohesive self-repair of the
materials were printed in a predetermined arrangement membrane defect, thereby obviating the necessity for
to replicate human ear cartilage, exhibiting durable manual shaping of the reparative material. The preliminary
and robust mechanical properties. Subsequently, the investigations into 3D bioprinting and MSCs resulted in
regenerated cartilage tissues were implanted in nude mice, the development of scaffolds composed of PCL, collagen,
displaying similarities to native rabbit auricular cartilage. and alginate-encapsulated MSCs. In comparison to
An important benefit of this method is the incorporation of scaffolds without cells, these cell-laden constructs
diverse cell types at specific sites, enabling the fabrication facilitated full recovery from subacute TMP in Sprague–
of diverse freeform 3D structures.
Dawley rats without notable adverse effects on their
Furthermore, researchers have employed bioprinting auditory function. Nonetheless, scholars posit that this
techniques to develop advanced bionic ears incorporating approach is most appropriate for treating non-severe

Volume 10 Issue 4 (2024) 107 doi: 10.36922/ijb.3497