3D Bioprinting in Otolaryngology: A Review

Abstract

The evolution of tissue engineering and 3D bioprinting has allowed for increased opportunities to generate musculoskeletal tissue grafts that can enhance functional and aesthetic outcomes in otolaryngology-head and neck surgery. Despite literature reporting successes in the fabrication of cartilage and bone scaffolds for applications in the head and neck, the full potential of this technology has yet to be realized. Otolaryngology as a field has always been at the forefront of new advancements and technology and is well poised to spearhead clinical application of these engineered tissues. In this review, current 3D bioprinting methods are described and an overview of potential cell types, bioinks, and bioactive factors available for musculoskeletal engineering using this technology is presented. The otologic, nasal, tracheal, and craniofacial bone applications of 3D bioprinting with a focus on engineered graft implantation in animal models to highlight the status of functional outcomes in vivo; a necessary step to future clinical translation are reviewed. Continued multidisciplinary efforts between material chemistry, biological sciences, and otolaryngologists will play a key role in the translation of engineered, 3D bioprinted constructs for head and neck surgery.

Keywords: 3D-printing; bioprinting; head and neck surgery; otolaryngology; tissue engineering.

Figure 1:. The 3D bioprinting process.

The 3D bioprinting process steps include pre-bioprinting, bioprinting, and post-bioprinting. Adapted from ^[18], no permissions required.

Figure 2.. 3D bioprinting for otologic applications.

A. Schematic of cell-printed scaffold (CPS) composed of chondrocytes encapsulated in alginate bioink printed with PCL framework. (a, b) autologous cartilage, (c) CPS, (d) defect site on the rabbit ear, and (e) defect creation, (f) implantation of the grafts into the cartilage defect of rabbit model. Figure adapted from ^[114], permissions obtained. B. Schematic diagram of digital near-infrared (NIR) photopolymerization (DNP)-based noninvasive 3D bioprinting. Figure adapted from ^[115], permissions not required. C. DNP-based 3D bioprinted, ear-shaped construct printed subcutaneously in BALB/c nude mice. Figure adapted from ^[115], permissions not required. Scale bar, 5 mm.

Figure 3.. 3D bioprinting for nasal applications.

A. Gross morphology of FRESH printed nasal alar structure composed of collagen type I hydrogel with incorporated human nasal chondrocytes (hNCs). Image (top) shows 3D model of a right lower lateral nasal cartilage from CT (top left) and a preview of sliced nasal cartilage using Slic3r software (top right). Image (bottom) shows nasal alar cartilage 3D bioprinted in a gelatin support bath before (bottom left) and 30 min after incubation in 37°C with removal of support bath (bottom right). Figure adapted from ^[123], permissions not required. B. Demonstration of gross morphology of 3D bioprinted nasal alar constructs and commercially available control (chondro-gide) scaffolds across culture time. Figure adapted from ^[123], permissions not required. C. Photograph of hNC-laden nanofibrillated cellulose/alginate hydrogel after 14 days of implantation. Figure adapted from ^[124], permissions not required. D. Histological evaluation of glycosaminoglycan deposition of hNC and hNC/human bone marrow mesenchymal stem cell (hBMSC)-laden nanofibrillated cellulose/alginate hydrogel at days 14, 30, and 60 of implantation. Scale bar, 100 μm. Figure adapted from ^[124], permissions not required.

Figure 4.. 3D bioprinting for tracheal applications.

A. 3D bioprinted artificial trachea, longitudinal and vertical view (top left). An SEM view of the five-layered structure (bottom left) shows (a,c,e) polycaprolactone (PCL) layers, (b) the alginate layer with mesenchymal stem cells (MSCs), and (d) the alginate layer with epithelial cells. Following implantation of the 3D bioprinted trachea in a rabbit model (top right), bronchoscopic images reveal fully epithelialized mucosa at 12 weeks post-surgery within the trachea inner lumen. Figure adapted from ^[126], permission not required. B. In vitro culture of a 4D-bioprinted trachea composed of hTBSCs to target the mucous membrane of the trachea as the base layer of the construct and hNCs for the hyaline cartilage ring to create a trachea-mimetic scaffold through shape morphing (top). Transplantation of the 4D bioprinted trachea into a partial defect rabbit trachea (bottom). Figure adapter from ^[128], permissions obtained.

Figure 5.. 3D bioprinting for maxillofacial bone applications.

A. Three-dimensional computer assisted design (CAD) model generated from a CT image of mandibular bony defect to 3D bioprint the tissue defect site. The 3D bioprinted graft was composed of human amniotic fluid–derived stem cells (hAFSCs) mixed with composite hydrogel of gelatin, fibrinogen, hyaluronic acid and glycerol co-printed with polycaprolactone, tricalcium phosphate, and Pluronic F127 as a temporary support. Scaffolds were cultured in osteogenic medium for 28 days followed by Alizarin Red S staining, indicating calcium deposition, a marker of osteogenesis. Figure adopted from ^[44], permissions obtained.