RESUMO
Augmentation of the nasal dorsum often requires implantation of structural material. Existing methods include autologous, cadaveric or alloplastic materials and injectable hydrogels. Each of these options is associated with considerable limitations. There is an ongoing need for precise and versatile implants that produce long-lasting craniofacial augmentation. Four separate polylactic acid (PLA) dorsal nasal implant designs were 3D-printed. Two implants had internal PLA rebar of differing porosities and two were designed as "shells" of differing porosities. Shell designs were implanted without infill or with either minced or zested processed decellularized ovine cartilage infill to serve as a "biologic rebar", yielding eight total treatment groups. Scaffolds were implanted heterotopically on rat dorsa (N = 4 implants per rat) for explant after 3, 6, and 12 months followed by volumetric, histopathologic, and biomechanical analysis. Low porosity implants with either minced cartilage or PLA rebar infill had superior volume retention across all timepoints. Overall, histopathologic and immunohistochemical analysis showed a resolving inflammatory response with an M1/M2 ratio consistently favoring tissue regeneration over the study course. However, xenograft cartilage showed areas of degradation and pro-inflammatory infiltrate contributing to volume and contour loss over time. Biomechanical analysis revealed all constructs had equilibrium and instantaneous moduli higher than human septal cartilage controls. Biocompatible, degradable polymer implants can induce healthy neotissue ingrowth resulting in guided soft tissue augmentation and offer a simple, customizable and clinically-translatable alternative to existing craniofacial soft tissue augmentation materials. PLA-only implants may be superior to combination PLA and xenograft implants due to contour irregularities associated with cartilage degradation.
RESUMO
Reconstruction of the human auricle remains a formidable challenge for plastic surgeons. Autologous costal cartilage grafts and alloplastic implants are technically challenging, and aesthetic and/or tactile outcomes are frequently suboptimal. Using a small animal "bioreactor", we have bioengineered full-scale ears utilizing decellularized cartilage xenograft placed within a 3D-printed external auricular scaffold that mimics the size, shape, and biomechanical properties of the native human auricle. The full-scale polylactic acid ear scaffolds were 3D-printed based upon data acquired from 3D photogrammetry of an adult ear. Ovine costal cartilage was processed either through mincing (1 mm3) or zesting (< 0.5 mm3), and then fully decellularized and sterilized. At explantation, both the minced and zested neoears maintained the size and contour complexities of the scaffold topography with steady tissue ingrowth through 6 months in vivo. A mild inflammatory infiltrate at 3 months was replaced by homogenous fibrovascular tissue ingrowth enveloping individual cartilage pieces at 6 months. All ear constructs were pliable, and the elasticity was confirmed by biomechanical analysis. Longer-term studies of the neoears with faster degrading biomaterials will be warranted for future clinical application. STATEMENT OF SIGNIFICANCE: Accurate reconstruction of the human auricle has always been a formidable challenge to plastic surgeons. In this article, we have bioengineered full-scale ears utilizing decellularized cartilage xenograft placed within a 3D-printed external auricular scaffold that mimic the size, shape, and biomechanical properties of the native human auricle. Longer-term studies of the neoears with faster degrading biomaterials will be warranted for future clinical application.