Flexural properties of native and tissue-engineered human septal cartilage

Properties of the Nasal Cartilage, from Development to Adulthood: A Scoping Review

OBJECTIVE

Nasal septum cartilage is a hyaline cartilage that provides structural support to the nasal cavity and midface. Currently, information on its cellular and mechanical properties is widely dispersed and has often been inferred from studies conducted on other cartilage types such as the knee. A detailed understanding of nasal cartilage properties is important for several biological, clinical, and engineering disciplines. The objectives of this scoping review are to (1) consolidate actual existing knowledge on nasal cartilage properties and (2) identify gaps of knowledge and research questions requiring future investigations.

DESIGN

This scoping review incorporated articles identified using PROSPERO, Cochrane Library (CDSR and Central), WOS BIOSIS, WOS Core Collection, and ProQuest Dissertations and Theses Global databases. Following the screening process, 86 articles were considered. Articles were categorized into three groups: growth, extracellular matrix, and mechanical properties.

RESULTS

Most articles investigated growth properties followed by extracellular matrix and mechanical properties. NSC cartilage is not uniform. Nasal cartilage growth varies with age and location. Similarly, extracellular matrix composition and mechanical properties are location-specific within the NSC. Moreover, most articles included in the review investigate these properties in isolation and only very few articles demonstrate the interrelationship between multiple cartilage properties.

CONCLUSIONS

This scoping review presents a first comprehensive description of research on NSC properties with a focus on NSC growth, extracellular matrix and mechanical properties. It additionally identifies the needs (1) to understand how these various cartilage properties intersect and (2) for more granular, standardized assessment protocols to describe NSC.

Multi-material 3D bioprinting of porous constructs for cartilage regeneration

The current gold standard for nasal reconstruction after rhinectomy or severe trauma includes transposition of autologous cartilage grafts in conjunction with coverage using an autologous skin flap. Harvesting autologous cartilage requires a major additional procedure that may create donor site morbidity. Major nasal reconstruction also requires sculpting autologous cartilages to form a cartilage framework, which is complex, highly skill-demanding and very time consuming. These limitations have prompted facial reconstructive surgeons to explore different techniques such as tissue engineered cartilage. This work explores the use of multi-material 3D bioprinting with chondrocyte-laden gelatin methacrylate (GelMA) and polycaprolactone (PCL) to fabricate constructs that can potentially be used for nasal reconstruction. In this study, we have investigated the effect of 3D manufacturing parameters including temperature, needle gauge, UV exposure time, and cell carrier formulation (GelMA) on the viability and functionality of chondrocytes in bioprinted constructs. Furthermore, we printed chondrocyte-laden GelMA and PCL into composite constructs to combine biological and mechanical properties. It was found that 20% w/v GelMA was the best concentration for the 3D bioprinting of the chondrocytes without comprising the scaffold's porous structure and cell functionality. In addition, the 3D bioprinted constructs showed neocartilage formation and similar mechanical properties to nasal alar cartilage after a 50-day culture period. Neocartilage formation was also observed in the composite constructs evidenced by the presence of glycosaminoglycans and collagen type II. This study shows the feasibility of manufacturing neocartilage using chondrocytes/GelMA/PCL 3D bioprinted porous constructs which could be applied as a method for fabricating implants for nose reconstruction.

Evaluation of human nasal cartilage nonlinear and rate dependent mechanical properties

Nasal reconstruction frequently requires donor cartilage and tissue, and ideally, donor tissue will closely emulate native nasal cartilage mechanics. Tissue engineering scaffolds, especially 3D printed scaffolds, have been proposed for nasal reconstruction, and the success of these constructs may depend on how well scaffolds reflect native nasal cartilage mechanical properties. Therefore, consistent and comprehensive characterization of native nasal cartilage mechanical properties is a foundation for nasal cartilage tissue engineering and reconstruction in general by providing design targets for reconstructive materials. Our group has previously shown the feasibility of producing scaffolds with porous architecture permitting chondrocyte growth and cartilage production. In this study, we determined the nonlinear and stress relaxation behavior of human nasal cartilage under unconfined compression. We then fit this experimental data to nonlinear elastic, nonlinear viscoelastic and nonlinear biphasic constitutive models. The resulting coefficients will provide design targets for nasal reconstruction and scaffold design as well as outcome measures for assessment of tissue engineered nasal cartilage.

Toward tissue-engineering of nasal cartilages

Nasal cartilage pathologies are common; for example, up to 80% of people are afflicted by deviated nasal septum conditions. Because cartilage provides the supportive framework of the nose, afflicted patients suffer low quality of life. To correct pathologies, graft cartilage is often required. Grafts are currently sourced from the patient's septum, ear, or rib. However, their use yields donor site morbidity and is limited by tissue quantity and quality. Additionally, rhinoplasty revision rates exceed 15%, exacerbating the shortage of graft cartilage. Alternative grafts, such as irradiated allogeneic rib cartilage, are associated with complications. Tissue-engineered neocartilage holds promise to address the limitations of current grafts. The engineering design process may be used to create suitable graft tissues. This process begins by identifying the surgeon's needs. Second, nasal cartilages' properties must be understood to define engineering design criteria. Limited investigations have examined nasal cartilage properties; numerous additional studies need to be performed to examine topographical variations, for example. Third, tissue-engineering processes must be applied to achieve the engineering design criteria. Within the recent past, strategies have frequently utilized human septal chondrocytes. As autologous and allogeneic rib graft cartilage is used, its suitability as a cell source should also be examined. Fourth, quantitative verification of engineered neocartilage is critical to check for successful achievement of the engineering design criteria. Finally, following the FDA paradigm, engineered neocartilage must be orthotopically validated in animals. Together, these steps delineate a path to engineer functional nasal neocartilages that may, ultimately, be used to treat human patients. STATEMENT OF SIGNIFICANCE: Nasal cartilage pathologies are common and lead to greatly diminished quality of life. The ability to correct pathologies is limited by cartilage graft quality and quantity, as well as donor site morbidity and surgical complications, such as infection and resorption. Despite the significance of nasal cartilage pathologies and high rhinoplasty revision rates (15%), little characterization and tissue-engineering work has been performed compared to other cartilages, such as articular cartilage. Furthermore, most work is published in clinical journals, with little in biomedical engineering. Therefore, this review discusses what nasal cartilage properties are known, summarizes the current state of nasal cartilage tissue-engineering, and makes recommendations via the engineering design process toward engineering functional nasal neocartilage to address current limitations.

Transplantation of Tissue-Engineered Cartilage in an Animal Model (Xenograft and Autograft): Construct Validation

Tissue engineering holds great promise for cartilage repair with minimal donor-site morbidity. The in vivo maturation of a tissue-engineered construct can be tested in the subcutaneous tissues of the same species for autografts or of immunocompromised animals for allografts or xenografts. This section describes detailed protocols for the surgical transplantation of a tissue-engineered construct into an animal model to assess construct validity.