Human nasal cartilage: Functional properties and structure-function relationships for the development of tissue engineering design criteria

Gelatin methacryloyl bioinks for bioprinting nasal cartilage: Balancing mechanical integrity and extracellular matrix formation

Gelatin methacryloyl (GelMA) is widely recognized as a versatile hydrogel, though few studies have examined its role in nasal cartilage engineering. In this study, we investigated how variations in GelMA concentration and lysyl oxidase-like 2 (LOXL2) supplementation would affect mechanical properties, extracellular matrix (ECM) deposition, and human nasoseptal chondrocyte remodeling in 3D bioprinted constructs. Using human serum-supplemented media to enhance clinical feasibility, we evaluated a Good Manufacturing Practices (GMP)-grade GelMA at 5, 10, and 15 % w/v. To improve mechanical properties, we investigated LOXL2's potential to enhance crosslinking of newly synthesized collagen, an approach not previously evaluated in gelatin biomaterials. After six weeks, higher GelMA concentrations increased stiffness, as demonstrated by suture pull-out, three-point bending, and compressive equilibrium moduli. However, improved mechanical performance accompanied a reduction in ECM deposition and elevated catabolic gene expression. These findings suggest that cells encapsulated in stiffer, more densely crosslinked constructs exhibited an altered anabolic-catabolic balance and chondrocyte behavior These results underscore the need to balance mechanical integrity with a microenvironment conducive to collagen synthesis and remodeling. By examining how GelMA concentration, crosslinking, and human serum-based conditions influence ECM deposition, this work advances macromolecular interactions in GelMA-based constructs in the development of clinically translatable cartilage grafts.

Cartilage Tissue Engineering in Multilayer Tissue Regeneration

The functional and structural integrity of the tissue/organ can be compromised in multilayer reconstructive applications involving cartilage tissue. Therefore, multilayer structures are needed for cartilage applications. In this review, we have examined multilayer scaffolds for use in the treatment of damage to organs such as the trachea, joint, nose, and ear, including the multilayer cartilage structure, but we have generally seen that they have potential applications in trachea and joint regeneration. In conclusion, when the existing studies are examined, the results are promising for the trachea and joint connections, but are still limited for the nasal and ear. It may have promising implications in the future in terms of reducing the invasiveness of existing grafting techniques used in the reconstruction of tissues with multilayered layers.

Challenges in Nasal Cartilage Tissue Engineering to Restore the Shape and Function of the Nose

The repair of nasal septal cartilage is a key challenge in cosmetic and functional surgery of the nose, as it determines its shape and its respiratory function. Supporting the dorsum of the nose is essential for both the prevention of nasal obstruction and the restoration of the nose structure. Most surgical procedures to repair or modify the nasal septum focus on restoring the external aspect of the nose by placing a graft under the skin, without considering respiratory concerns. Tissue engineering offers a more satisfactory approach, in which both the structural and biological roles of the nose are restored. To achieve this goal, nasal cartilage engineering research has led to the development of scaffolds capable of accommodating cartilaginous extracellular matrix-producing cells, possessing mechanical properties close to those of the nasal septum, and retaining their structure after implantation in vivo. The combination of a non-resorbable core structure with suitable mechanical properties and a biocompatible hydrogel loaded with autologous chondrocytes or mesenchymal stem cells is a promising strategy. However, the stability and immunotolerance of these implants are crucial parameters to be monitored over the long term after in vivo implantation, to definitively assess the success of nasal cartilage tissue engineering. Here, we review the tissue engineering methods to repair nasal cartilage, focusing on the type and mechanical characteristics of the biomaterials; cell and implantation strategy; and the outcome with regard to cartilage repair. Impact statement Nasal septal cartilage is key to the cosmetic and function of the nose. To repair important damage to the nasal septum, current surgical techniques are complex and limited by graft source availability. Conversely, tissue engineering is a promising strategy to reproduce the dimensions and mechanical properties of the nose without causing donor site morbidity. This approach, however, remains overlooked for the reconstruction of the nasal septum compared with other cartilaginous tissues. This review describes the specific challenges associated with nasal cartilage repair and the pioneering studies leading to advances in the growing field of nose tissue engineering.

Human Septal Cartilage Tissue Engineering: Current Methodologies and Future Directions

Nasal septal cartilage tissue engineering is a promising and dynamic field with the potential to provide surgical options for patients with complex reconstruction needs and mitigate the risks incurred by other tissue sources. Developments in cell source selection, cell expansion, scaffold creation, and three-dimensional (3D) bioprinting have advanced the field in recent years. The usage of medicinal signaling cells and nasal chondroprogenitor cells can enhance chondrocyte proliferation, stimulate chondrocyte growth, and limit chondrocyte dedifferentiate. New scaffolds combined with recent innovations in 3D bioprinting have allowed for the creation of more durable and customizable constructs. Future developments may increase technical accessibility and manufacturability, and lower costs, to help incorporate these methods into pre-clinical studies and clinical applications of septal cartilage tissue engineering.

Tissue Engineering Nasal Cartilage Grafts with Three-Dimensional Printing: A Comprehensive Review

Nasal cartilage serves a crucial structural function for the nose, where rebuilding the cartilaginous framework is an essential aspect of nasal reconstruction. Conventional methods of nasal reconstruction rely on autologous cartilage harvested from patients, which contributes to donor site pain and the potential for site-specific complications. Some patients are not ideal candidates for this procedure due to a lack of adequate substitute cartilage due to age-related calcification, differences in tissue quality, or due to prior surgeries. Tissue engineering, combined with three-dimensional printing technologies, has emerged as a promising method of generating biomimetic tissues to circumvent these issues to restore normal function and aesthetics. We conducted a comprehensive literature review to examine the applications of three-dimensional printing in conjunction with tissue engineering for the generation of nasal cartilage grafts. This review aims to compare various approaches and discuss critical considerations in the design of these grafts.

Distribution of Immunomodulation, Protection and Regeneration Factors in Cleft-Affected Bone and Cartilage

BACKGROUND

Craniofacial clefts can form a significant defect within bone and cartilage, which can negatively affect tissue homeostasis and the remodeling process. Multiple proteins can affect supportive tissue growth, while also regulating local immune response and tissue protection. Some of these factors, like galectin-10 (Gal-10), nuclear factor kappa-light-chain-enhancer of activated B cells protein 65 (NF-κB p65), heat shock protein 60 (HSP60) and 70 (HSP70) and cathelicidin (LL-37), have not been well studied in cleft-affected supportive tissue, while more known tissue regeneration regulators like type I collagen (Col-I) and bone morphogenetic proteins 2 and 4 (BMP-2/4) have not been assessed jointly with immunomodulation and protective proteins. Information about the presence and interaction of these proteins in cleft-affected supportive tissue could be helpful in developing biomaterials and improving cleft treatment.

METHODS

Two control groups and two cleft patient groups for bone tissue and cartilage, respectively, were organized with five patients in each group. Immunohistochemistry with the semiquantitative counting method was implemented to determine Gal-10-, NF-κB p65-, HSP60-, HSP70-, LL-37-, Col-I- and BMP-2/4-positive cells within the tissue.

RESULTS

Factor-positive cells were identified in each study group. Multiple statistically significant correlations were identified.

CONCLUSIONS

A significant increase in HSP70-positive chondrocytes in cleft patients could indicate that HSP70 might be reacting to stressors caused by the local tissue defect. A significant increase in Col-I-positive osteocytes in cleft patients might indicate increased bone remodeling and osteocyte activity due to the presence of a cleft. Correlations between factors indicate notable differences in molecular interactions within each group.

Composite Thickness and Stiffness Analysis of the Nasal Septum

Background: The nasal septum supports the structure of the nose and is frequently manipulated during septorhinoplasty. Objective: To compare measurements of thickness and compressive Young's modulus (YM) between different regions of nasal septa from human anatomic specimens. Study Design: Case series. Methods: Cartilaginous septa from human anatomic specimens were dissected. Septum thickness was measured at 24 points with regular intervals using a digital caliper. Compressive YM was determined at 14 regions using a force gauge. Two-tailed student's t-tests were used to compare the average thickness and YM between different regions. Results: Septa from 40 human anatomic specimens were included, with age ranging from 50 to 89. Fifty percent of specimens were female. The mean (standard deviation) thickness of the septum was 1.75 (0.76) mm. The mean YM was 2.38 (1.29) MPa. The septum was thickest near the maxillary crest (3.09 [1.17] mm) and the keystone area (2.52 [0.91] mm) and thinnest near the anterior septal angle (1.29 [0.58] mm). The septum was most stiff posteriorly (2.90 [1.32] MPa) and least stiff anteriorly (1.80 [1.15] MPa). Conclusion: The nasal septum is thickest posteriorly, inferiorly, and along its bony edges. The septum is stiffest posteriorly, ventrally, and along its bony edges.

Innovative Non-Surgical Plastic Technique for Saddle Nose Correction: A Study on 97 Patients

Background: Non-surgical rhinoplasty is one of the best choices in mild cases of the saddle nose, and it represents a solution for the aesthetical amelioration of facial deformity; nevertheless, in most critical cases, surgical intervention is still required. This study reports the experience and results of a single facial plastic surgeon (M.G.) using a non-surgical technique for the correction of saddle noses in a large cohort of patients. Methods: This retrospective study assesses all patients injected from January 2017 through October 2023 in private clinics in Milan (Italy), London (UK), and Dubai (UAE). All patients were followed up for 12 months. The harvested adipose tissues were processed with different systems and with or without acoustic wave therapy (AWT). The extracted products have been characterized in terms of cellular yield and cell growth. Ninety-seven patients were injected with adipose-derived products or hyaluronic acid (HA). Patients were followed up for 12 months, and satisfaction data were analyzed. Results: The stem cells obtained from the patients who previously received AWT displayed a statistically higher cell growth ability in comparison with those of the cells derived from patients who did not receive AWT. The evolution of patient satisfaction during the time for each group of treatment was investigated, and cellular treatments show the best maintenance of patient satisfaction over time. Conclusions: Dermgraft and AWT approaches resulted in the highest patient satisfaction for the non-surgical correction of the saddle nose deformity.

Usefulness of T2-Weighted Images with Deep-Learning-Based Reconstruction in Nasal Cartilage

OBJECTIVE

This study aims to evaluate the feasibility of visualizing nasal cartilage using deep-learning-based reconstruction (DLR) fast spin-echo (FSE) imaging in comparison to three-dimensional fast spoiled gradient-echo (3D FSPGR) images.

MATERIALS AND METHODS

This retrospective study included 190 set images of 38 participants, including axial T1- and T2-weighted FSE images using DLR (T1WIDL and T2WIDL, belong to FSEDL) and without using DLR (T1WIO and T2WIO, belong to FSEO) and 3D FSPGR images. Subjective evaluation (overall image quality, noise, contrast, artifacts, and identification of anatomical structures) was independently conducted by two radiologists. Objective evaluation including signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was conducted using manual region-of-interest (ROI)-based analysis. Coefficient of variation (CV) and Bland-Altman plots were used to demonstrate the intra-rater repeatability of measurements for cartilage thickness on five different images.

RESULTS

Both qualitative and quantitative results confirmed superior FSEDL to 3D FSPGR images (both p < 0.05), improving the diagnosis confidence of the observers. Lower lateral cartilage (LLC), upper lateral cartilage (ULC), and septal cartilage (SP) were relatively well delineated on the T2WIDL, while 3D FSPGR showed poorly on the septal cartilage. For the repeatability of cartilage thickness measurements, T2WIDL showed the highest intra-observer (%CV = 8.7% for SP, 9.5% for ULC, and 9.7% for LLC) agreements. In addition, the acquisition time for T1WIDL and T2WIDL was respectively reduced by 14.2% to 29% compared to 3D FSPGR (both p < 0.05).

CONCLUSIONS

Two-dimensional equivalent-thin-slice T1- and T2-weighted images using DLR showed better image quality and shorter scan time than 3D FSPGR and conventional construction images in nasal cartilages. The anatomical details were preserved without losing clinical performance on diagnosis and prognosis, especially for pre-rhinoplasty planning.