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This review aims to investigate the properties of growth factors concerning the morphogenesis and development of nasal cartilage, which is fundamentally important for facial form and appearance. Since cartilage lacks a blood supply, it is more difficult to regenerate, as cartilage tissue obtains sustenance by diffusion. Cytokines are signalling molecules that control chondrocyte metabolism and extracellular matrix formation, which is required for cartilage development, homeostasis, and healing. Some craniofacial illnesses alter the composition of the cartilage and the structural organization of growth factors, allowing for moulding. TGF-ß (transforming growth factor-ß) encourages chondrocyte differentiation, whereas IGF-1 (insulin-like growth factor-1) stimulates cartilage-forming collagen synthesis and chondrocyte multiplication. We used the scoping review approach to present current research on the role of growth factors in the creation and architecture of nasal cartilage. We generally observed this structure before conducting specific experiments to determine the impact of growth agents on the development of chondrocytes and cartilage. Prominent findings increase our understanding of how growth factors influence the extracellular matrix, cell activities and features, and cartilage growth rate; all are critical for cartilage tissue development and repair. Research into growth factors and their physiological interactions with cartilage may help improve treatment's functional and aesthetic outcomes and our understanding of the origins and consequences of nasal congenital anomalies. This study emphasizes the importance of expanding knowledge and experience, as well as the use of growth factors in clinical practice, to stimulate cartilage development.

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BACKGROUND: The aesthetic importance of nasal tip and the complexity of its surgical correction make the surgery of this area one of the most fascinating facial surgical procedures. Despite description of different sculpturing techniques to correct nasal tip defects, this surgery remains one of the most discussed and challenging aesthetic procedures. OBJECTIVES: The objective of this study was to define an algorithm of treatment for nasal tip surgery based on 40-year experience on Caucasian patients evaluated by our proposed clinical qualitative assessment, who were treated by closed rhinoplasty. METHODS: We retrospectively reviewed 19,643 Caucasian patients (15,266 females and 4,377 males) who underwent primary closed rhinoplasty from 1979 to 2019 due to different tip defects. The patients were evaluated by volume projection rotation (VPR) assessment. The surgical indications options, long-term aesthetic results and complications were analysed. RESULTS: 22% patients with minimal nasal defects were treated by non-delivery approach and 78% patients with important tip malformation by delivery approach. In all cases, the surgery was performed to reduce tip volume and modify tip projection and rotation based on the specific nasal defects. 67% patients, who needed important reduction of tip projection, were treated by tip-interrupting techniques. 88.7% patients declared full satisfaction after surgery, and only 12.3% needed a requiring minor revision surgery during the 20 years follow-up. CONCLUSION: The proposed algorithm may be a useful tool to plan surgery. The use of an adequate technique depending on the evaluation of volume, projection and rotation may guarantee higher patients satisfaction and a stable long-term aesthetic result. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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This study employs an optimized and environmentally friendly method to extract and purify chondroitin sulfate (CS) from bovine nasal cartilage using enzymatic hydrolysis, ethanol precipitation, and DEAE Sepharose Fast Flow column chromatography. The extracted CS, representing 44.67 % ± 0.0016 of the cartilage, has a molecular weight of 7.62 kDa. Characterization through UV, FT-IR, NMR spectroscopy, and 2-aminoacridone derivatization HPLC revealed a high content of sulfated disaccharides, particularly ΔDi4S (73.59 %) and ΔDi6S (20.61 %). Interaction studies with bovine serum albumin (BSA) using fluorescence spectroscopy and molecular docking confirmed a high-affinity, static quenching interaction with a single binding site, primarily mediated by van der Waals forces and hydrogen bonding. The interaction did not significantly alter the polarity or hydrophobicity of BSA aromatic amino acids. These findings provide a strong foundation for exploring the application of CS in tissue engineering and drug delivery systems, leveraging its unique interaction with BSA for targeted delivery and enhanced efficacy.

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Natural hydrogels are widely employed in tissue engineering and have excellent biodegradability and biocompatibility. Unfortunately, the utilization of such hydrogels in the field of three-dimensional (3D) printing nasal cartilage is constrained by their subpar mechanical characteristics. In this study, we provide a multicrosslinked network hybrid ink made of photocurable gelatin, hyaluronic acid, and acrylamide (AM). The ink may be processed into intricate 3D hydrogel structures with good biocompatibility and high stiffness properties using 3D printing technology based on digital light processing (DLP), including intricate shapes resembling noses. By varying the AM content, the mechanical behavior and biocompatibility of the hydrogels can be adjusted. In comparison to the gelatin methacryloyl (GelMA)/hyaluronic acid methacryloyl (HAMA) hydrogel, adding AM considerably enhances the hydrogel's mechanical properties while also enhancing printing quality. Meanwhile, the biocompatibility of the multicrosslinked network hydrogels and the development of cartilage were assessed using neonatal Sprague-Dawley (SD) rat chondrocytes (CChons). Cells sown on the hydrogels considerably multiplied after 7 days of culture and kept up the expression of particular proteins. Together, our findings point to GelMA/HAMA/polyacrylamide (PAM) hydrogel as a potential material for nasal cartilage restoration. The photocuring multicrosslinked network ink composed of appropriate proportions of GelMA/HAMA/PAM is very suitable for DLP 3D printing and will play an important role in the construction of nasal cartilage, ear cartilage, articular cartilage, and other tissues and organs in the future. Notably, previous studies have not explored the application of 3D-printed GelMA/HAMA/PAM hydrogels for nasal cartilage regeneration.

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Background: Tissue engineering is a multidisciplinary field that combines principles from cell biology, bioengineering, material sciences, medicine and surgery to create functional and viable bioproducts that can be used to repair or replace damaged or diseased tissues in the human body. The complexity of tissue engineering can affect the prospects of efficiently translating scientific discoveries in the field into scalable clinical approaches that could benefit patients. Organizational challenges may play a key role in the clinical translation of tissue engineering for the benefit of patients. Methods: To gain insight into the organizational aspects of tissue engineering that may create impediments to efficient clinical translation, we conducted a retrospective qualitative case study of one tissue engineering multi-site translational project on knee cartilage engineered tissue grafts. We collected qualitative data using a set of different methods: semi-structured interviews, documentary research and audio-visual content analysis. Results: Our study identified various challenges associated to first-in-human trials in tissue engineering particularly related to: logistics and communication; research participant recruitment; clinician and medical student participation; study management; and regulation. Conclusions: While not directly generalizable to other types of advanced therapies or to regenerative medicine in general, our results offer valuable insights into organizational barriers that may prevent efficient clinical translation in the field of tissue engineering.

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INTRODUCTION: Nasal valve compromise is a common issue for patients presenting to an otolaryngologist. Anatomically, the dorsal septal cartilage (DSA) articulates with the upper lateral nasal cartilage (ULC). When the ULC weakens, it is prone to collapse and may result in nasal obstruction. Our objectives were to analyze histological differences between quadrangular and DSA nasal cartilages and compare histological composition of these tissues among patients with diagnosis of nasal valve compromise (NVC) versus those without NVC (no NVC). METHODS: Prospective cross-sectional study of nasal cartilages from seventy-three (73) live donors. Quadrangular cartilage (QC), and DSA from patients undergoing septorhinoplasty were collected. Safranin O histochemical staining was used to observe glycosaminoglycans (GAGs) content and cell count. Masson's Trichrome staining was used to assess collagen content in these nasal cartilages. RESULTS: Mean GAG content was lower in DSA compared with QUAD cartilage (68.18% vs. 87.22%, p < 0.0001), and was lowest in DSA of patients with NVC (59.07%). Mean collagen content was higher in DSA compared with QUAD cartilage, (65.43% vs. 46.65%, p = 0.0002), and was highest in DSA of patients with NVC (74.86%). CONCLUSION: The DSA showed decreased GAG and increased collagen content compared with quadrangular cartilage. Within the DSA subsite, patients with presurgical NVC had the lowest GAG and highest collagen levels. This observation suggests that the biochemical composition of the DSA may contribute to its weakening, potentially resulting in its inability to withstand minor trauma and/or the effects of aging, ultimately leading to NVC. LEVEL OF EVIDENCE: N/A Laryngoscope, 2024.

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Aim This study aimed to determine and compare the cytotoxicity of light-cured composite resin (Enlight light cure composite (Ormco, Glendora, California, USA)), light-cured acrylic resin (Orthocryl LC (Dentaurum, Ispringen, Germany)), and the self-cure acrylic (DPI RR cold cure acrylic (Dental Products of India, Bombay Burmah Trading Corporation Ltd., Mumbai, India)) material and to determine which component is best to be used for the purpose of nasal stent fabrication in the nasoalveolar molding (NAM) technique for cleft therapy. Methods Circular discs made from Enlight light cure composite, Orthocryl LC, and self-cure acrylic were submerged for 24 hours in gingival fibroblast media (three discs of each material) and control medium (three discs of each material) that were both contained in plates. After analyzing the optical densities of the plates, the cytotoxicity of the products was assessed by measuring cell viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The compiled data was analyzed using IBM SPSS Statistics for Windows, V. 23.0 (IBM Corp., Armonk, NY). The normality of the data was evaluated using the Shapiro-Wilk test. One-way analysis of variance (ANOVA) and pairwise comparison made with Tukey's honestly significant difference (HSD) post hoc test with a significance level (p) of 0.05 were considered. Results The percentage of cell viability was between 80% and 150%. A significant mean difference was noted in the cell viability between the three groups (p=0.009). High mean cell viability was seen in Orthocryl LC. However, there was no significant mean difference between Orthocryl LC and Enlight light cure composite material (p=0.854). Conclusion Both Orthocryl LC and Enlight light cure composite materials are less cytotoxic when compared to the self-cure acrylic resin material and can be used to fabricate the nasal stent component for infants with cleft defects, undergoing NAM procedure.

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Nasal cartilage diseases and injuries are known as significant challenges in reconstructive medicine, affecting a substantial number of individuals worldwide. In recent years, the advent of three-dimensional (3D) bioprinting has emerged as a promising approach for nasal cartilage reconstruction, offering potential breakthroughs in the field of regenerative medicine. This paper provides an overview of the methods and challenges associated with 3D bioprinting technologies in the procedure of reconstructing nasal cartilage tissue. The process of 3D bioprinting entails generating a digital 3D model using biomedical imaging techniques and computer-aided design to integrate both internal and external scaffold features. Then, bioinks which consist of biomaterials, cell types, and bioactive chemicals, are applied to facilitate the precise layer-by-layer bioprinting of tissue-engineered scaffolds. After undergoing in vitro and in vivo experiments, this process results in the development of the physiologically functional integrity of the tissue. The advantages of 3D bioprinting encompass the ability to customize scaffold design, enabling the precise incorporation of pore shape, size, and porosity, as well as the utilization of patient-specific cells to enhance compatibility. However, various challenges should be considered, including the optimization of biomaterials, ensuring adequate cell viability and differentiation, achieving seamless integration with the host tissue, and navigating regulatory attention. Although numerous studies have demonstrated the potential of 3D bioprinting in the rebuilding of such soft tissues, this paper covers various aspects of the bioprinted tissues to provide insights for the future development of repair techniques appropriate for clinical use.

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New supplements with preventive effects against skin photodamage are receiving increasing attention. This study evaluated the anti-photoaging effects of salmon nasal cartilage proteoglycan (SPG), acting as a functional material for skin health. We administered SPG to in vitro and in vivo models exposed to ultraviolet B (UVB) radiation and assessed its moisturizing and anti-wrinkle effects on dorsal mouse skin and keratinocytes and dermal fibroblasts cell lines. These results showed that SPG restored the levels of filaggrin, involucrin, and AQP3 in the epidermis of UVB-irradiated dorsal skin and keratinocytes, thereby enhancing the keratinization process and water flow. Additionally, SPG treatment increased the levels of hyaluronan and skin ceramide, the major components of intercellular lipids in the epidermis. Furthermore, SPG treatment significantly increased the levels of collagen and procollagen type 1 by down-regulating matrix metalloproteinase 1, which play a crucial role in skin fibroblasts, in both in vitro and in vivo models. In addition, SPG strongly inhibited mitogen-activated protein kinase (MAPKs) signaling, the including extracellular signal-regulated kinase, c-Jun N-terminal kinase (JNK), and p38. These findings suggest that dietary SPG may be an attractive functional food for preventing UVB-induced photoaging. And this SPG product may provide its best benefit when treating several signs of skin photoaging.

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Neural crest cells (NCC) arise from the dorsal margin of the neural plate border and comprise a unique cell population that migrates to and creates the craniofacial region. Although factors including Shh, Fgf8, and bone morphogenetic proteins have been shown to regulate these biological events, the role of parathyroid hormone 1 receptor (Pth1r) has been less studied. We generated an NCC-specific mouse model for Pth1r and researched gene expression, function, and interaction focusing on nasal cartilage framework and midfacial development. Wnt1-Cre;Pth1rfl/fl;Tomatofl/+ mice had perinatal lethality, but we observed short snout and jaws, tongue protrusion, reduced NCC-derived cranial length, increased mineralization in nasal septum and hyoid bones, and less bone mineralization at interfrontal suture in mutants at E18.5. Importantly, the mutant nasal septum and turbinate cartilage histologically revealed gradual, premature accelerated hypertrophic differentiation. We then studied the underlying molecular mechanisms by performing RNA seq analysis and unexpectedly found that expression of Ihh and related signaling molecules was enhanced in mutant nasomaxillary tissues. To see if Pth1r and Ihh signaling are associated, we generated a Wnt1-Cre; Ihhfl/fl;Pth1rfl/fl;Tomatofl/+ (DKO) mouse and compared the phenotypes to those of each single knockout mouse: Wnt1-Cre; Ihhfl/fl;Pth1rfl/+;Tomatofl/+ (Ihh-CKO) and Wnt1-Cre;Ihhfl/+;Pth1rfl/fl;Tomatofl/+ (Pth1r-CKO). Ihh-CKO mice displayed a milder effect. Of note, the excessive hypertrophic conversion of the nasal cartilage framework observed in Pth1r-CKO was somewhat rescued DKO embryos. Further, a half cAMP responsive element and the 4 similar sequences containing 2 mismatches were identified from the promoter to the first intron in Ihh gene. Gli1-CreERT2;Pth1rfl/fl;Tomatofl/+, a Pth1r-deficient model targeted in hedgehog responsive cells, demonstrated the enlarged hypertrophic layer and significantly more Tomato-positive chondrocytes accumulated in the nasal septum and ethmoidal endochondral ossification. Collectively, the data suggest a relevant Pth1r/Ihh interaction. Our findings obtained from novel mouse models for Pth1r signaling illuminate previously unknown aspects in craniofacial biology and development.

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OBJECTIVE: Analyze age-related changes in histologic features and biochemical properties of human auricular cartilage and two subsites of nasal cartilages (quadrangular cartilage and dorsal septal articulation with upper lateral cartilages). STUDY DESIGN: Prospective cross-sectional study of nasal and auricular cartilages from seventy-three (73) live donors. METHODS: Auricular cartilage (AC), quadrangular cartilage (QC), and dorsal septal cartilage articulation (DSA) with the upper lateral cartilage (ULCs) were collected intraoperatively. Histochemical staining was used: Safranin O for glycosaminoglycans (GAGs), Verhoeff's for elastin, and Masson's trichrome for collagen. ImageJ2 software was used to calculate cell count and percent stained for each cartilage type. R studio "ggplot" package was used to visualize age versus cell count or percent stained. RESULTS: Participant ages ranged from 20 to 77 years, average 46.5 years. There was a significant decline in GAGs with age for the DSA subsite, (n = 64, p < 0.001). Significant increase in collagen content with age was observed for DSA subsite (n = 66, p < 0.001) and the QC subsite (n = 64, p < 0.05). There was a statistically insignificant decline in elastin with age (n = 41, p = 0.309) for AC. Cell count declined with age at all cartilage subsites. CONCLUSION: Our findings confirm that there were age-related decreases in cartilage glycosaminoglycan content, and chondrocyte cell count in both auricular and nasal cartilages. We have also confirmed that collagen content increases with age for both auricular and nasal cartilage. The histologic findings while not statistically significant in all comparisons, provides additional evidence that there is some loss of structural integrity and flexibility in nasal and auricular cartilage with aging. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1220-1226, 2024.

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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.

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BACKGROUND: The demand for rhinoplasty in Asia is growing annually, and short nose deformity has been one of the main reasons for the surgery due to its high incidence. There is an urgent need for rhinoplasty suitable for Asians because of their different facial features from Westerners. The M-shaped auricular cartilage rhinoplasty has been developed as a new method for correcting short nose deformity for Asians. This study aimed to evaluate the aesthetic and functional results of M-shaped auricular cartilage rhinoplasty compared to clinically commonly used rhinoplasty methods. METHODS: A total of 45 patients were enrolled and divided into three groups of 15 patients: The first group underwent M-shaped auricular cartilage rhinoplasty, the second group underwent auricular-septal cartilage rhinoplasty, and the third group underwent overlapped auricular cartilage rhinoplasty. All of these patients underwent comprehensive rhinoplasty and had silicone or expanded polytetrafluoroethylene implants in the dorsum of their noses. RESULTS: The patient score improvements on the three patient-reported outcome measures were higher in the M-shaped auricular cartilage rhinoplasty group (1.65/1.79/0.11) compared with the overlapped auricular cartilage rhinoplasty group (1.40/1.51/0.05), and the score improvements in the auricular-septal cartilage rhinoplasty group (2.04/1.98/0.28) were the highest. CONCLUSIONS: This is a retrospective clinical study demonstrating the clinical efficacy of M-shaped auricular cartilage rhinoplasty. Compared with the overlapped auricular cartilage rhinoplasty, the effect of this novel M-shaped method is better. However, when compared to the auricular-septal cartilage rhinoplasty with septal extension and reinforcement using nasal septal cartilage, its effect is slightly worse. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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The nasal septal cartilage plays an important role in preventing the collapse of the nasal bones and maintaining the appearance of the nose. In the context of inherent difficulties regarding septal cartilage repair and the shortage of cartilage graft resources for regeneration, tissue engineering, especially the in situ strategy based on scaffolds, has become a new prospect and become one of the most promising approaches. Given that it is difficult for chondrocytes to achieve directional migration and secrete matrix components to participate in tissue repair after cartilage injury, cartilage progenitor cells (CPCs), with great migratory ability and stem cell characteristics, have caught the attention of researchers and brought hope for nasal septal cartilage in situ regeneration. In this review, we first summarized the distribution, characteristics, isolation, and culture methods of nasal septal CPCs. Subsequently, we described the roles of migratory CPCs in cartilage regeneration. Finally, we reviewed the existing studies on CPCs-based cartilage tissue engineering and summarized the strategies for promoting the migration and chondrogenesis of CPCs so as to provide ideas for achieving nasal septal cartilage in situ regeneration.

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BACKGROUND: Using M-shaped cartilage grafts is a new method for the correction of short nose deformity with good effect for Asians. Although the basic approach to M-shaped cartilage surgery is well understood, there is a great deal of uncertainty when plastic surgeons perform the procedure, and still a lack of standard guidance on the specific details. METHODS: In this study, the authors used finite element analysis to explore and compare postoperative cartilage stability of different fixing methods, different suturing positions, and different sizes of M-shaped cartilage. The authors applied a 0.01 N load to a 1 cm2 area of the nasal tip to simulate nasal tip palpation and compared the maximum deformations of different groups, which were used to make stability judgments. RESULTS: The maximum deformation of the model was the least when the M-shaped cartilage was fixed medially to the septal cartilage and laterally to the outer crura of the lower lateral cartilage. At the same time, the maximum deformation was the least when the M-shaped cartilage was sutured to the middle of the nasal septal cartilage. Besides, the length of M-shaped cartilage was preferably around 30 mm, while its width was not worthy of being overly concerned. CONCLUSIONS: For optimal postoperative stability of Asian short nose correction, the M-shaped cartilage should be sutured and fixed medially to the middle of the septal cartilage and laterally to the lateral crura of the lower lateral cartilage, and the length of the M-shaped cartilage should be controlled at around 30 mm. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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BACKGROUND: Porcine nasal cartilage type II collagen-derived peptides (PNCPs) may be complexed with calcium to provide a highly bioavailable, low-cost, and effective calcium food supplement. However, the calcium-binding characteristics of PNCPs have not yet been investigated. In the present study, calcium-binding peptides were derived from porcine nasal cartilage type II collagen and the resulting PNCPs-Ca complex was characterized. RESULTS: The study reveals that the calcium-binding capacity of PNCPs is closely related to enzymatic hydrolysis conditions. The highest calcium-binding capacity of PNCPs was observed at a hydrolysis time of 4 h, temperature of 40 °C, enzyme dosage of 1%, and solid-to-liquid ratio of 1:10. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed that the PNCPs had a pronounced capacity for calcium binding, with the PNCPs-Ca complex exhibiting a clustered structure consisting of aggregated spherical particles. Fourier-transform infrared spectroscopy, fluorescence spectroscopy, X-ray diffraction, dynamic light scattering, amino acid composition, and molecular weight distribution analyses all indicated that the PNCPs and calcium complexed via the carboxyl oxygen and amino nitrogen atoms, leading to the formation of a ß-sheet structure during the chelation process. In addition, the stability of the PNCPs-Ca complex was maintained over a range of pH values consistent with those found in the human gastrointestinal tract, facilitating calcium absorption. CONCLUSION: These research findings suggest the feasibility of converting by-products from livestock processing into calcium-binding peptides, providing a scientific basis for the development of novel calcium supplements and the potential reduction of resource waste. © 2023 Society of Chemical Industry.

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Septoplasty is a widely used method in treating deviated septum. Although it is successfully implemented, there are problems with excessive bleeding, septal perforation, or infections. The use of anatomically shaped implants could help overcome these problems. This paper focuses on assessing the possibility of the usage of a nasal septum cartilage implant 3D printed from various market-available filaments. Five different types of laments were used, two of which claim to be suitable for medical use. A combination of modeling, mechanical (bending, compression), structural (FTIR), thermal (DSC, MFR), surface (contact angle), microscopic (optical), degradation (2 M HCl, 5 M NaOH, and 0.01 M PBS), printability, and cell viability (MTT) analyses allowed us to assess the suitability of materials for manufacturing implants. Bioflex had the most applicable properties among the tested materials, but despite the overall good performance, cell viability studies showed toxicity of the material in MTT test. The results of the study show that selected filaments were not suitable for nasal cartilage implants. The poor cell viability of Bioflex could be improved by surface modification. Further research on biocompatible elastic materials for 3D printing is needed either by the synthesis of new materials or by modifying existing ones.

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Hydrogels appear to be an attractive class of biomaterial for cartilage tissue engineering due to their high water content, excellent biocompatibility, tunable stiffness, etc. The crosslinking density of the hydrogel can affect their viscoelastic property, and therefore potentially impact the chondrogenic phenotype of re-differentiated chondrocytes in a 3D microenvironment through physical cues. To understand the effect of crosslinking densities on chondrocytes phenotype and cellular interaction with the hydrogel, this study utilized a clinical grade thiolate hyaluronic acid and thiolate gelatin (HA-Gel) hydrogel, crosslinked with poly(ethylene glycol) diacrylate to create various crosslinking densities. The HA-Gel hydrogels were then mixed with human nasal chondrocytes to generate neocartilage in vitro. The influence of the hydrogel crosslinking density and the viscoelastic property on the cell behaviours on the gene and matrix levels were evaluated using biochemistry assays, histology, quantitative polymerase chain reaction (qPCR) and next-generation sequencing (RNA seq). In general, the differences in the storage modulus of the HA-Gel hydrogel are not enough to alter the cartilaginous gene expression of chondrocytes. However, a positively correlated trend of PPAR-γ gene expression to the crosslinking density was measured by qPCR. The RNA-seq results have shown that 178 genes are significantly negatively correlated and 225 genes are positively correlated to the crosslinking density, which is worth investigating in the future studies.

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Due to the limited self-repair capacity of the hyaline cartilage, the repair of cartilage remains an unsolved clinical problem. Tissue engineering strategy with 3D bioprinting technique has emerged a new insight by providing patient's personalized cartilage grafts using autologous cells for hyaline cartilage repair and regeneration. In this review, we first summarized the intrinsic property of hyaline cartilage in both maxillofacial and orthopedic regions to establish the requirement for 3D bioprinting cartilage tissue. We then reviewed the literature and provided opinion pieces on the selection of bioprinters, bioink materials, and cell sources. This review aims to identify the current challenges for hyaline cartilage bioprinting and the directions for future clinical development in bioprinted hyaline cartilage.

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BACKGROUND: A 1-2-mm thin rib cartilage graft was used as a septal extension graft to overcome the drawbacks of traditional rib cartilage rhinoplasty, which often results in a stiff nasal tip. The remaining rib cartilage was placed on the nasal dorsum as an ultrafine diced cartilage wrapped in fascia (UDCWF) graft. This study aimed to assess the stability of thin rib cartilage grafts and measure the resorption rate of the UDCWF graft. METHODS: This retrospective study included 53 patients who underwent rhinoplasty with septal extension grafting and nasal dorsum augmentation using a septal cartilage (SC group) or rib cartilage (RC group) graft between June 2017 and June 2020. The nasal length, tip height, sellion height, and nasolabial angle in the preoperative, immediate postoperative, and long-term postoperative periods were analyzed using three-dimensional photogrammetry. RESULTS: A total of 26 patients received rib cartilage grafts and 27 patients received septal cartilage grafts. The RC group showed greater maintenance of tip height, nasal length, and tip derotation over time. The relapse ratio in tip height was -3.3 ± 1.6% and -8.4 ± 4.3% in the RC and SC groups, respectively (p = 0.001). The resorption rate of the UDCWF graft was -7.5 ± 3.6% and -7.8 ± 2.3% at the sellion and rhinion, respectively. CONCLUSIONS: The thin rib cartilage provided sufficient intrinsic strength to maintain tip height and tip rotation. It can be an effective alternative to rhinoplasty in Asians with features such as thick skin and a short nose. Moreover, the UDCWF graft exhibited an approximately 7.5% resorption rate, leading to lower probabilities of dorsal irregularity and stepping deformity.

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