In vivo implantation of tissue-engineered human nasal septal neocartilage constructs: a pilot study

Tissue Engineering and Regenerative Medicine in the Field of Otorhinolaryngology

BACKGROUND

Otorhinolaryngology is a medical specialty that focuses on the clinical study and treatments of diseases within head and neck regions, specifically including the ear, nose, and throat (ENT), but excluding eyes and brain. These anatomical structures play significant roles in a person's daily life, including eating, speaking as well as facial appearance and expression, thus greatly impacting one's overall satisfaction and quality of life. Consequently, injuries to these regions can significantly impact a person's well-being, leading to extensive research in the field of tissue engineering and regenerative medicine over many years.

METHODS

This chapter provides an overview of the anatomical characteristics of otorhinolaryngologic tissues and explores the tissue engineering and regenerative medicine research in otology (ear), rhinology (nose), facial bone, larynx, and trachea.

RESULTS AND CONCLUSION

The integration of tissue engineering and regenerative medicine in otorhinolaryngology holds the promise of broadening the therapeutic choices for a wide range of conditions, ultimately improving quality of a patient's life.

Application of Tissue Engineering and Biomaterials in Nose Surgery

Surgery of the nose involves a series of operations that are directed at restoring the nasal anatomy and physiology. The extent or degree of reconstruction needed is dependent on the appearance-based requirement of the patients and the procedure exploited for the correction such that nasal airflow is preserved. Standard surgical approach includes the use of autologous tissue or implantation alloplastic bio or synthetic/fabricated construct materials to correct the defects. Over the years, tissue engineering has been proven to be a promising technique for reconstructing tissue and organ defects, including the nose. Recently, there has been keen interest in fabricating new tissues and organ scaffolds using 3D printing technology with good control over the micro-architecture and excellent interior architecture suitable for cell seeding. Unviability of the tissue and harvest-associated complications have increased the need for the investigation of tissue engineering based methods for nasal reconstruction using biomaterials, stem cells, and growth factors combined with 3D bioprinting. However, there are only a handful of studies vis-à-vis the application of cartilage tissue engineering, stem cells, and growth factors for the purpose. This review provides highlights about the available studies based on the application of stem cells, biomaterials, and growth factors for nasal reconstruction surgery, as there is limited recent information on the use of these entities in nasal surgeries.

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.

Tissue engineering in otorhinolaryngology: A knowledge-based analysis

Objective

To analyze the impact, performance, degree of specialization, and collaboration patterns of the worldwide scientific production on tissue engineering in otorhinolaryngology at the level of countries and institutions.

Methods

Two different techniques were used, performance and science mapping analyses, using as samples all the available documents regarding tissue engineering focused on otorhinolaryngology applications. The dataset was retrieved from the Core Collection of the Web of Science database from 1900 to 2020. Social structure was analyzed using science mapping analysis with VOSviewer software.

Results

The United States was the main producer, followed by Germany, and Japan. Malaysia and Germany had the highest Relative Specialization Index, indicating their greater relative interest in this area compared to other countries. The social structure analysis showed that the United States and Germany had significant co-authorship relationships with other countries. The University of California System, Kyoto University, and Harvard University were the leading institutions producing literature in this field. These latter two institutions showed the largest number of collaborations, although most of them were with institutions within their own country. There was a lack of connections between different communities of research.

Conclusion

The United States is the main country driving progress in this research area, housing the most notable institutions. However, significant collaborations between these research centers are currently lacking. Encouraging greater cooperation among these institutions and their researchers would promote the exchange of knowledge, ultimately facilitating and accelerating advancements in this field.

Nuclear Factor-κB Decoy Oligodeoxynucleotide Attenuates Cartilage Resorption In Vitro

BACKGROUND

Cartilage harvest and transplantation is a common surgery using costal, auricular, and septal cartilage for craniofacial reconstruction. However, absorption and warping of the cartilage grafts can occur due to inflammatory factors associated with wound healing. Transcription factor nuclear factor-κB (NF-κB) is activated by the various stimulation such as interleukin-1 (IL-1), and plays a central role in the transactivation of this inflammatory cytokine gene. Inhibition of NF-κB may have anti-inflammatory effects. The aim of this study was to explore the potential of an NF-κB decoy oligodeoxynucleotide (Decoy) as a chondroprotective agent.

MATERIALS AND METHODS

Safe and efficacious concentrations of Decoy were assessed using rabbit nasal septal chondrocytes (rNSChs) and assays for cytotoxicity, proteoglycan (PG) synthesis, and PG turnover were carried out. The efficacious concentration of Decoy determined from the rNSChs was then applied to human nasal septal cartilage (hNSC) in vitro and analyzed for PG turnover, the levels of inflammatory markers, and catabolic enzymes in explant-conditioned culture medium.

RESULTS

Over the range of Decoy conditions and concentrations, no inhibition of PG synthesis or cytotoxicity was observed. Decoy at 10 μM effectively inhibited PG degradation in the hNSC explant, prolonging PG half-life by 63% and decreasing matrix metalloprotease 3 (MMP-3) by 70.7% (p = 0.027).

CONCLUSIONS

Decoy may be considered a novel chondroprotective therapeutic agent in cartilage transplantation due to its ability to inhibit cartilage degradation due to inflammation cytokines.

Cartilage Tissue Engineering for Nasal Alar and Auricular Reconstruction: A Critical Review of the Literature and Implications for Practice in Dermatologic Surgery

BACKGROUND

Reconstructing defects requiring replacement of nasal or auricular cartilage after Mohs micrographic surgery can at times be challenging. While autologous cartilage grafting is considered the mainstay for repair, it may be limited by cartilage quality/quantity, donor site availability/morbidity, and surgical complications. Tissue-engineered cartilage has recently shown promise for repairing properly selected facial defects.

OBJECTIVE

To (1) provide a comprehensive overview of the literature on the use of tissue-engineered cartilage for nasal alar and auricular defects, and (2) discuss this technology's advantages and future implications for dermatologic surgery.

MATERIALS AND METHODS

A literature search was performed using PubMed/MEDLINE and Google Scholar databases. Studies discussing nasal alar or auricular cartilage tissue engineering were included.

RESULTS

Twenty-seven studies were included. Using minimal donor tissue, tissue-engineered cartilage can create patient-specific, three-dimensional constructs that are biomechanically and histologically similar to human cartilage. The constructs maintain their shape and structural integrity after implantation into animal and human models.

CONCLUSION

Tissue-engineered cartilage may be able to replace native cartilage in reconstructing nasal alar and auricular defects given its ability to overcome several limitations of autologous cartilage grafting. Although further research is necessary, dermatologic surgeons should be aware of this innovative technique and its future implications.

The Need for Innovation in Rhinoplasty

Rhinoplasty is a challenging surgery and results are not always perfect. There are many obstacles to achieving optimal results. Among these are inadequate instrumentation, the unpredictability of healing, imprecise planning, and many more. Furthermore, selecting patients who can most benefit from surgery is equally important. In this article, some of the more pressing areas of rhinoplasty that need innovation are discussed. From proper patient selection, to advances in education, to the standardization of training programs, to the development of sophisticated implants, the future of rhinoplasty surgery lies in continued creativity and innovation.

Promising Implants in Rhinoplasty

Many dilemmas in rhinoplasty tempt surgeons to use exogenous materials. We have long looked toward implants to decrease operative time, to achieve a more reliable result, or when there is a paucity of autologous material. More than ever, the innovative and highly lucrative field of nasal implantology is developing technologically advanced products. This article looks at some popular nasal implant choices with a look toward what might be on the horizon.

Progress of 3D Printing Techniques for Nasal Cartilage Regeneration

Once cartilage is damaged, its self-repair capacity is very limited. The strategy of tissue engineering has brought a new idea for repairing cartilage defect and cartilage regeneration. In particular, nasal cartilage regeneration is a challenge because of the steady increase in nasal reconstruction after oncologic resection, trauma, or rhinoplasty. From this perspective, three-dimensional (3D) printing has emerged as a promising technology to address the complexity of nasal cartilage regeneration, using patient's image data and computer-aided deposition of cells and biomaterials to precisely fabricate complex, personalized tissue-engineered constructs. In this review, we summarized the major progress of three prevalent 3D printing approaches, including inkjet-based printing, extrusion-based printing and laser-assisted printing. Examples are highlighted to illustrate 3D printing for nasal cartilage regeneration, with special focus on the selection of seeded cell, scaffolds and growth factors. The purpose of this paper is to systematically review recent research about the challenges and progress and look forward to the future of 3D printing techniques for nasal cartilage regeneration.Level of Evidence III This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/00266 .

Achievements and Challenges in Transplantation of Mesenchymal Stem Cells in Otorhinolaryngology

Otorhinolaryngology enrolls head and neck surgery in various tissues such as ear, nose, and throat (ENT) that govern different activities such as hearing, breathing, smelling, production of vocal sounds, the balance, deglutition, facial animation, air filtration and humidification, and articulation during speech, while absence of these functions can lead to high morbidity and even mortality. Conventional therapies for head and neck damaged tissues include grafts, transplants, and artificial materials, but grafts have limited availability and cause morbidity in the donor site. To improve these limitations, regenerative medicine, as a novel and rapidly growing field, has opened a new therapeutic window in otorhinolaryngology by using cell transplantation to target the healing and replacement of injured tissues. There is a high risk of rejection and tumor formation for transplantation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); mesenchymal stem cells (MSCs) lack these drawbacks. They have easy expansion and antiapoptotic properties with a wide range of healing and aesthetic functions that make them a novel candidate in otorhinolaryngology for craniofacial defects and diseases and hold immense promise for bone tissue healing; even the tissue sources and types of MSCs, the method of cell introduction and their preparation quality can influence the final outcome in the injured tissue. In this review, we demonstrated the anti-inflammatory and immunomodulatory properties of MSCs, from different sources, to be safely used for cell-based therapies in otorhinolaryngology, while their achievements and challenges have been described too.

Cartilage tissue engineering for craniofacial reconstruction

Severe cartilage defects and congenital anomalies affect millions of people and involve considerable medical expenses. Tissue engineering offers many advantages over conventional treatments, as therapy can be tailored to specific defects using abundant bioengineered resources. This article introduces the basic concepts of cartilage tissue engineering and reviews recent progress in the field, with a focus on craniofacial reconstruction and facial aesthetics. The basic concepts of tissue engineering consist of cells, scaffolds, and stimuli. Generally, the cartilage tissue engineering process includes the following steps: harvesting autologous chondrogenic cells, cell expansion, redifferentiation, in vitro incubation with a scaffold, and transfer to patients. Despite the promising prospects of cartilage tissue engineering, problems and challenges still exist due to certain limitations. The limited proliferation of chondrocytes and their tendency to dedifferentiate necessitate further developments in stem cell technology and chondrocyte molecular biology. Progress should be made in designing fully biocompatible scaffolds with a minimal immune response to regenerate tissue effectively.

Alginate Formulations: Current Developments in the Race for Hydrogel-Based Cardiac Regeneration

Cardiovascular diseases, including myocardial infarction (MI), represent the main worldwide cause of mortality and morbidity. In this scenario, to contrast the irreversible damages following MI, cardiac regeneration has emerged as a novel and promising solution for in situ cellular regeneration, preserving cell behavior and tissue cytoarchitecture. Among the huge variety of natural, synthetic, and hybrid compounds used for tissue regeneration, alginate emerged as a good candidate for cellular preservation and delivery, becoming one of the first biomaterial tested in pre-clinical research and clinical trials concerning cardiovascular diseases. Although promising results have been obtained, recellularization and revascularization of the infarcted area present still major limitations. Therefore, the demand is rising for alginate functionalization and its combination with molecules, factors, and drugs capable to boost the regenerative potential of the cardiac tissue. The focus of this review is to elucidate the promising properties of alginate and to highlight its benefits in clinical trials in relation to cardiac regeneration. The definition of hydrogels, the alginate characteristics, and recent biomedical applications are herewith described. Afterward, the review examines in depth the ongoing developments to refine the material relevance in cardiac recovery and regeneration after MI and presents current clinical trials based on alginate.

Neural Crest-Derived Chondrocytes Isolation for Tissue Engineering in Regenerative Medicine

Chondrocyte transplantation has been successfully tested and proposed as a clinical procedure aiming to repair articular cartilage defects. However, the isolation of chondrocytes and the optimization of the enzymatic digestion process, as well as their successful in vitro expansion, remain the main challenges in cartilage tissue engineering. In order to address these issues, we investigated the performance of recombinant collagenases in tissue dissociation assays with the aim of isolating chondrocytes from bovine nasal cartilage in order to establish the optimal enzyme blend to ensure the best outcomes of the overall procedure. We show, for the first time, that collagenase H activity alone is required for effective cartilage digestion, resulting in an improvement in the yield of viable cells. The extracted chondrocytes proved able to grow and activate differentiation/dedifferentiation programs, as assessed by morphological and gene expression analyses.

Neural Crest-Derived Chondrocytes Isolation for Tissue Engineering in Regenerative Medicine

Chondrocyte transplantation has been successfully tested and proposed as a clinical procedure aiming to repair articular cartilage defects. However, the isolation of chondrocytes and the optimization of the enzymatic digestion process, as well as their successful in vitro expansion, remain the main challenges in cartilage tissue engineering. In order to address these issues, we investigated the performance of recombinant collagenases in tissue dissociation assays with the aim of isolating chondrocytes from bovine nasal cartilage in order to establish the optimal enzyme blend to ensure the best outcomes of the overall procedure. We show, for the first time, that collagenase H activity alone is required for effective cartilage digestion, resulting in an improvement in the yield of viable cells. The extracted chondrocytes proved able to grow and activate differentiation/dedifferentiation programs, as assessed by morphological and gene expression analyses.

Clinical Application of 3-Dimensional Printing Technology for Patients With Nasal Septal Deformities: A Multicenter Study

Importance

Studies have shown the controllability and porosity of polycaprolactone as well as the use of 3-dimensional (3-D) printing for nasal reconstruction in animal models. The utility of polycaprolactone with 3-D technology in nasal cartilaginous framework reconstruction in humans remains unknown.

Objective

To investigate the safety and efficacy of 3-D printed, bioresorbable polycaprolactone nasal implants.

Design, Setting, and Participants

This multicenter clinical trial comprised 20 patients with caudal septal deviations who underwent septoplasty, which used a 3-D printed polycaprolactone mesh, at 2 centers in South Korea. Patients were included if they were aged 18 to 74 years and had nasal septal deviations, Nasal Obstruction Symptom Evaluation scores greater than 20, and persistent nasal obstructions. Twenty-two patients met the inclusion criteria, but 2 patients were excluded before the operation. The study was conducted from July 1, 2016, to June 30, 2017.

Main Outcomes and Measures

The change in total Nasal Obstruction Symptom Evaluation score between the preoperative examination and the week 12 postoperative examination was the primary outcome. Changes in bilateral nasal cavity minimum cross-sectional area and volume on acoustic rhinometry at weeks 4 and 12 after the operation as well as changes in the nasal cavity cross-sectional area at the osteomeatal unit and nasal septum angle in the paranasal sinus on computed tomography after week 12 were among the secondary outcomes.

Results

Of the 20 patients included in the study, 4 (20%) were female, 16 (80%) were male, with a mean (SD) age of 34.95 (11.96) years. The preoperative and week 12 postoperative results revealed significant changes in the minimal cross-sectional areas on acoustic rhinometry (0.41 [SD, 0.39] vs -0.11 [SD, 0.18]; difference, 0.42; 95% CI, 0.23-0.61), nasal septum angles on computed tomography (11.22 [SD, 6.57] vs 2.89 [SD, 3.12]; difference, 8.33; 95% CI, 5.08-11.58), and Nasal Obstruction Symptom Evaluation scores (73.50 [SD, 19.88] vs 3.75 [SD, 6.26]; difference, 69.75; 95% CI, 59.22-80.28). The surgeons' convenience level with the procedure was favorable (visual analog scale score [SD], 90.90 [9.45]), and so were the patients' symptom improvements and satisfaction after 12 weeks (visual analog scale score [SD], 88.30 [9.87]).

Conclusions and Relevance

The 3-D printed, homogeneous, composite, microporous polycaprolactone nasal implant demonstrated proper mechanical support and thinness with excellent biocompatibility and surgical manipulability. Polycaprolactone may be a clinically biocompatible material for use in various craniofacial reconstructions in the future.

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.

Generating Mechanically Stable, Pediatric, and Scaffold-Free Nasal Cartilage Constructs In Vitro

Traditional methods of cartilage tissue engineering rely on the use of scaffolds. Although successful chondrogenesis has been reported in scaffold-based constructs, the use of exogenous materials has limited their application due to eliciting host immunogenic responses and potentially resulting in construct failure. As a result, tissue engineering approaches, which aim to generate scaffold-free cartilaginous constructs, have become of particular interest. Here, we generated stable three-dimensional scaffold-free cartilaginous constructs by cultivating expanded pediatric nasal chondrocyte multilayers in a slow turning lateral vessel bioreactor system under chemically defined media. Bioreactor cultivation resulted in increased construct cellularity, fourfold tissue thickness, and 200% sulfated glycosaminoglycan deposition with respect to static culture equivalent cultures. These improvements led to significantly enhanced mechanical and biochemical properties of bioreactor-cultivated constructs, allowing them to support their own weight, while static culture constructs remained fragile. Consequently, bioreactor-cultivated constructs closely resembled native nasal cartilage tissue histologically, mechanically, and biochemically. We propose that this method of cartilage construct formation could be used to obtain readily available human scaffold-free cartilaginous constructs.

Nasal chondrocytes as a neural crest-derived cell source for regenerative medicine

Cells deriving from neural crest are generally acknowledged during embryonic development for their multipotency and plasticity, accounting for their capacity to generate various cell and tissue types even across germ layers. At least partial preservation of some of these properties in adulthood makes neural crest derived cells of large interest for regenerative purposes. Chondrocytes from fully mature nasal septum cartilage in adults are also derivatives of neural crest cells and were recently demonstrated to be able not only to maintain functionality across serial cloning, as surrogate self-renewal test, but also to respond and adapt to heterotopic transplantation sites. Based on these findings, cartilage grafts engineered by nasal chondrocytes were clinically used to reconstitute the nasal alar lobule and to repair articular cartilage defects. This article discusses further perspectives of potential clinical utility for nasal chondrocytes in musculoskeletal regeneration. It then highlights the need to derive deeper understanding of their biological properties in order to inform on possible therapeutic modes of action. This acquired knowledge will help to optimise manufacturing conditions to guarantee defined functional traits associated with safety and therapeutic potency of nasal chondrocytes in regenerative medicine.

New application of three-dimensional printing biomaterial in nasal reconstruction

OBJECTIVES

Polycaprolactone (PCL) is an U.S. Food and Drug Administration-approved synthetic biodegradable polymer and is easily fabricated into three-dimensional (3D) structures. In this study, the 3D-printed PCL implant for nasal augmentation was further evaluated for its suitability for nasal surgeries such as septoplasty and rhinoplasty.

METHODS

Ten New Zealand White rabbits were included and divided into study and sham groups (7 and 3, respectively). A lateral incision was made on the nasal dorsum and a pocket formed in the subperichondrial plane between the upper lateral cartilage and nasal septum. Polycaprolactone was fabricated based on 3D printing technology into a 0.8 × 0.8-cm rectangular shape for use as a nasal implant. The material was inserted as a septal extension graft and sutured with alar cartilage for nasal reshaping. The implants were harvested 4, 8, and 12 weeks after implantation and evaluated by gross morphological assessment and histological examination.

RESULTS

The initial shape of the implant was unchanged in all cases, and no definitive postoperative complications were seen over the 3-month period. Gross morphological evaluation confirmed that implants remained in their initial location without migration or extrusion. Histologic evaluations showed that the implant architectures were maintained with excellent fibrovascular ingrowth and minimal inflammatory reactions.

CONCLUSION

Polycaprolactone can be used for nasal reconstruction such as nasal augmentation. Polycaprolactone is easy to work with and will avoid the increased operative time and morbidity associated with autograft harvesting. Therefore, PCL implants designed by 3D printing can serve as clinically biocompatible materials in craniofacial reconstruction in the future.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:1036-1043, 2017.

Scaffold-free cartilage tissue engineering with a small population of human nasoseptal chondrocytes

OBJECTIVE

Cartilage tissue engineering is a promising approach to provide suitable materials for nasal reconstruction; however, it typically requires large numbers of cells. We have previously shown that a small number of chondrocytes cultivated within a continuous flow bioreactor can elicit substantial tissue growth, but translation to human chondrocytes is not trivial. Here, we aimed to demonstrate the application of the bioreactor to generate large-sized tissues from a small population of primary human nasoseptal chondrocytes.

STUDY DESIGN

Experimental study.

METHODS

Chondrocytes were cultured in the bioreactor using different medium compositions, with varying amounts of serum and with or without growth factors. Resulting engineered tissues were analyzed for physical properties, biochemical composition, tissue microstructure, and protein localization.

RESULTS

Bioreactor-cultivated constructs grown with serum and growth factors (basic fibroblast growth factor and transforming growth factor beta 2) had greater thickness, as well as DNA and glycosaminoglycan (GAG) contents, compared to low serum and no growth factor controls. These constructs also showed the most intense proteoglycan and collagen II staining.

CONCLUSION

The combination of bioreactor conditions, serum, and growth factors allowed the generation of large, thick scaffold-free human cartilaginous tissues that resembled the native nasoseptal cartilage. There also may be implications for patient selection in future clinical applications of these engineered tissues because their GAG content decreased with donor age.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:E91-E99, 2017.

Alginate: Current Use and Future Perspectives in Pharmaceutical and Biomedical Applications

Over the last decades, alginates, natural multifunctional polymers, have increasingly drawn attention as attractive compounds in the biomedical and pharmaceutical fields due to their unique physicochemical properties and versatile biological activities. The focus of the paper is to describe biological and pharmacological activity of alginates and to discuss the present use and future possibilities of alginates as a tool in drug formulation. The recent technological advancements with using alginates, issues related to alginates suitability as matrix for three-dimensional tissue cultures, adjuvants of antibiotics, and antiviral agents in cell transplantation in diabetes or neurodegenerative diseases treatment, and an update on the antimicrobial and antiviral therapy of the alginate based drugs are also highlighted.

Tissue-engineered cartilage for facial plastic surgery

PURPOSE OF REVIEW

The reconstruction of cartilaginous craniofacial defects is ideally performed with analogous grafting material, such as autologous tissue. However, the use of autologous cartilage is limited by its finite availability and potentially suboptimal geometry to repair specific defects. Tissue engineering of human cartilage may provide the adequate supply of grafting and implant material for the reconstruction of cartilaginous facial defects. An update of the various cartilage tissue engineering methodologies is provided in this review.

RECENT FINDINGS

The cartilage tissue engineering paradigm begins with the harvest of a small septal cartilage donor specimen. This is followed by the isolation and subsequent proliferation of chondrocytes and the seeding of these cells onto three-dimensional scaffolds. Neocartilage is created as pericellular substrate, is produced by the cells and deposited throughout the scaffold. Theoretically, the mature cartilage construct can be introduced back into the same patient for reconstruction of craniofacial defects. Initial steps of the cartilage tissue engineering protocol have been standardized; however, modifications of subsequent steps have shown the potential to profoundly impact tissue composition and strength, bringing the properties of cartilage constructs closer to those of native human septum.

SUMMARY

The ability to engineer virtually limitless quantities of autologous cartilage could have a profound impact on facial plastic and reconstructive surgery. The strategies used to refine human cartilage culture techniques have successfully produced neocartilage constructs with biochemical and biomechanical properties approaching those of native septal tissue. With the steady progress achieved in recent years, there is great capacity for the proximate realization of surgically implantable tissue-engineered cartilage constructs.

Regenerative medicine and nasal surgery

Nasal surgery is a constellation of operations that are intended to restore form and function to the nose. The amount of augmentation required for a given case is a delicate interplay between patient aesthetic desires and corrective measures taken for optimal nasal airflow. Traditional surgical techniques make use of autologous donor tissue or implanted alloplastic materials to restore nasal deficits. Limited availability of donor tissue and associated harvest site morbidity have pushed surgeons and researchers to investigate methods to bioengineer nasal tissues. For this article, we conducted a review of the literature on regenerative medicine as it pertains to nasal surgery. PubMed was searched for articles dating from January 1, 1994, through August 1, 2014. Journal articles with a focus on regenerative medicine and nasal tissue engineering are included in this review. Our search found that the greatest advancements have been in the fields of mucosal and cartilage regeneration, with a growing body of literature to attest to its promise. With recent advances in bioscaffold fabrication, bioengineered cartilage quality, and mucosal regeneration, the transition from comparative animal models to more expansive human studies is imminent. Each of these advancements has exciting implications for treating patients with increased efficacy, safety, and satisfaction.

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.

Engineered nasal cartilage by cell homing: a model for augmentative and reconstructive rhinoplasty

BACKGROUND

Current augmentative and reconstructive rhinoplasties use auto logous tissue grafts or synthetic bioinert materials to repair nasal trauma or attain an aesthetic shape. Autologous grafts are associated with donor-site trauma and morbidity. Synthetic materials are widely used but often yield an unnatural appearance and are prone to infection or dislocation. There is an acute clinical need for the generation of native tissues to serve as rhinoplasty grafts without the undesirable features that are associated with autologous grafts or current synthetic materials.

METHODS

Bioactive scaffolds were developed that not only recruited cells in the nasal dorsum in vivo, but also induced chondrogenesis of the recruited cells. Bilayered scaffolds were fabricated with alginate-containing gelatin microspheres encapsulating cytokines atop a porous poly(lactic-co-glycolic acid) base. Microspheres were fabricated to contain recombinant human transforming growth factor-β3 at doses of 200, 500, or 1000 ng, with phosphate-buffered saline-loaded microspheres used as a control. A rat model of augmentation rhinoplasty was created by implanting scaffolds atop the native nasal cartilage surface that was scored to induce cell migration. Tissue formation and chondrogenesis in the scaffolds were evaluated by image analysis and histologic staining with hematoxylin and eosin, toluidine blue, Verhoeff elastic-van Geison, and aggrecan immunohistochemistry.

RESULTS

Sustained release of increasing doses of transforming growth factor-β3 for up to the tested 10 weeks promoted orthotopic cartilage-like tissue formation in a dose-dependent manner.

CONCLUSIONS

These findings represent the first attempt to engineer cartilage tissue by cell homing for rhinoplasty, and could potentially serve as an alternative material for augmentative and reconstructive rhinoplasty.

Evaluation of Autogenous Engineered Septal Cartilage Grafts in Rabbits- A Minimally Invasive Preclinical Model

OBJECTIVES

Evaluate safety of autogenous engineered septal neocartilage grafts.Compare properties of implanted grafts versus in vitro controls.

STUDY DESIGN

Prospective, basic science.

SETTING

Research laboratory.

METHODS

Constructs were fabricated from septal cartilage and serum harvested from adult rabbits and then cultured in vitro or implanted on the nasal dorsum as autogenous grafts for 30 or 60 days. Rabbits were monitored for local and systemic complications. Histological, biochemical and biomechanical properties of implanted and in vitro constructs were evaluated and compared.

RESULTS

No systemic or serious local complications were observed. After 30 and 60 days, implanted constructs contained more DNA (p<0.01) and less sGAG per DNA (p<0.05) when compared with in vitro controls. Confined compressive aggregate moduli were also higher in implanted constructs when compared with in vitro controls (p<0.05) and increased with longer in vivo incubation time (p<0.01). Implanted constructs displayed resorption rates of 20-45 percent. Calcium deposition in implanted constructs was observed using alizarin red histochemistry and microtomographic analyses.

CONCLUSION

Autogenous engineered septal cartilage grafts were well tolerated. As seen in experiments with athymic mice, implanted constructs accumulated more DNA and less sGAG when compared with in vitro controls. Confined compressive aggregate moduli were also higher in implanted constructs. Implanted constructs displayed resorption rates similar to previously published studies using autogenous implants of native cartilage. The basis for observed calcification in implanted constructs and its effect on long-term graft efficacy is unknown at this time and will be a focus of future studies.

Volume Expansion of Tissue Engineered Human Nasal Septal Cartilage

IMPORTANCE

Cartilaginous craniofacial defects range in size and autologous cartilaginous tissue is preferred for repair of these defects. Therefore, it is important to have the ability to produce large size cartilaginous constructs for repair of cartilaginous abnormalities.

OBJECTIVES

To produce autologous human septal neocartilage constructs substantially larger in size than previously produced constructsTo demonstrate that volume expanded neocartilage constructs possess comparable histological and biochemical properties to standard size constructsTo show that volume expanded neocartilage constructs retain similar biomechanical properties to standard size constructs.

DESIGN

Prospective, basic science.

SETTING

Laboratory.

PARTICIPANTS

The study used remnant human septal specimens removed during routine surgery at the University of California, San Diego Medical Center or San Diego Veterans Affairs Medical Center. Cartilage from a total of 8 donors was collected.

MAIN OUTCOMES MEASURED

Human septal chondrocytes from 8 donors were used to create 12mm and 24mm neocartilage constructs. These were cultured for a total of 10 weeks. Photo documentation, histological, biochemical, and biomechanical properties were measured and compared.

RESULTS

The 24mm diameter constructs were qualitatively similar to the 12mm constructs. They possessed adequate strength and durability to be manually manipulated. Histological analysis of the constructs demonstrated similar staining patterns in standard and volume expanded constructs. Proliferation, as measured by DNA content, was similar in 24mm and 12mm constructs. Additionally, glycosaminoglycan (GAG) and total collagen content did not significantly differ between the two construct sizes. Biomechanical analysis of the 24mm and 12mm constructs demonstrated comparable compressive and tensile properties.

CONCLUSION AND RELEVANCE

Volume expanded human septal neocartilage constructs are qualitatively and histologically similar to standard 12mm constructs. Biochemical and biomechanical analysis of the constructs demonstrated equivalent properties. This study shows that modification of existing protocols is not required to successfully produce neocartilage constructs in larger sizes for reconstruction of more substantial craniofacial defects.

LEVEL OF EVIDENCE

NA.

[Techniques for correction of the nasal dorsum]

Correction of the nasal dorsum ranks among the most common surgical procedures in rhinoplasty. Due to the involvement of nasal support structures such as septolateral cartilage and the K and scroll areas, these procedures have both aesthetic and functional impacts. In addition to spreader grafts and spreader flaps, the most important surgical methods currently include the split hump reduction technique, cartilage-fascia transplants and cartilage grafts from rib and ear. In addition to serving to correct deformities, the techniques described here help prevent complications such as inverted V, hourglass and saddle nose deformities, as well as nasal valve stenosis. The basic operative principle calls for reinforcement and reconstruction of the anatomical support structures, while avoiding overresection and mucosal lacerations.

A compositional analysis of cadaveric human nasal septal cartilage

OBJECTIVES/HYPOTHESIS

To localize quantitatively the major biochemical constituents of native adult human septal cartilage across whole septa.

STUDY DESIGN

Prospective, basic science.

METHODS

The nasal septa from seven cadavers were partitioned into 24 separate regions: six from caudal to cephalic and four from dorsal to ventral. Biochemical assays were used to determine the quantities, relative to wet weight, of the major constituents of cartilage: chondrocytes, collagen, and sulfated glycosaminoglycan.

RESULTS

On average, each milligram of wet cartilage contained 24,900 cells, 73.9 μg collagen, and 17.1 μg sulfated glycosaminoglycan. Cell number showed no significant variation across the septa. In contrast, the caudal regions of the septa were associated with higher levels of collagen, the ventral regions correlated with higher levels of sulfated glycosaminoglycan, and the dorsal regions were associated with an elevated ratio of collagen to sulfated glycosaminoglycan.

CONCLUSIONS

This study represents the first characterization of the biochemical composition of native human septal cartilage across whole septa. Quantities of collagen and sulfated glycosaminoglycan showed region-specific variation across the septum. The localized pattern of collagen and sulfated glycosaminoglycan deposition are consistent with the significance of preserving the L-strut during rhinoplasty and other nasal reconstructive procedures. In addition, it may assist in defining design goals for tissue-engineered septal neocartilage constructs to meet specific reconstructive needs in the future.

Shape fidelity of native and engineered human nasal septal cartilage

OBJECTIVE

To test engineered and native septal cartilage for resistance to deformation and remodeling under sustained bending loads and to determine the effect of bending loads on the biochemical properties of constructs.

STUDY DESIGN

Prospective, basic science.

SETTING

Laboratory.

SUBJECTS AND METHODS

Human septal chondrocytes from 6 donors were used to create 12-mm constructs. These were cultured for 10 weeks and subjected to bending for 6 days. Free-swelling controls and native tissue from 6 donors were used for comparison. Shape retention, photo documentation, live-dead staining, and biochemical properties were measured.

RESULTS

Live-dead staining showed no difference in cell survival between loaded constructs and free-swelling controls. The immediate shape retention of the constructs was 39.0% versus 24.4% for native tissue (P = .13). After 2 and 24 hours of relaxation, the constructs possessed similar shape retention to native tissue (26.9% and 16.4%; P = .126; 21.7% and 14.4%; P = .153). There was no significant change in construct shape retention from immediately after release to 2 hours of relaxation (39.0% and 26.9%, respectively; P = .238). In addition, the retention did not change significantly between 2 and 24 hours of relaxation (26.9% and 21.7%; P = .48). There was no significant difference in biochemical properties between loaded constructs and controls.

CONCLUSION

The shape retention properties of human septal neocartilage constructs are comparable to human native septal cartilage. In addition, mechanical loading of neocartilage constructs does not adversely affect cell viability or biochemical properties. This study demonstrates that neocartilage constructs possess adequate shape fidelity for use as septal cartilage graft material.

Culture of human septal chondrocytes in a rotary bioreactor

OBJECTIVES

(1) To show that extracellular matrix deposition in 3-dimensional culture of human septal chondrocytes cultured in a rotary bioreactor is comparable to the deposition achieved under static culture conditions. (2) To demonstrate that the biomechanical properties of human septal chondrocytes cultured in a bioreactor are enhanced with time and are analogous to beads cultured under static culture.

STUDY DESIGN

Prospective, basic science.

SETTING

Research laboratory.

METHODS

Human septal chondrocytes from 9 donors were expanded in monolayer and seeded in alginate beads. The beads were cultured in a rotary bioreactor for 21 days in media supplemented with growth factors and human serum, using static culture as the control. Biochemical and biomechanical properties of the beads were measured.

RESULTS

Glycosaminoglycan (GAG) accumulation significantly increased during 2 measured time intervals, 0 to 21 days and 10 to 21 days (P < .01). No significant difference was seen between the static and bioreactor conditions. Substantial type II collagen production was demonstrated in the beads terminated at day 21 of culture in both conditions. In addition, the biomechanical properties of the beads were significantly improved at 21 days in comparison to beads from day 0.

CONCLUSION

Human septal chondrocytes cultured in alginate beads exhibit significant matrix deposition and improved biomechanical properties after 21 days. Alginate bead diameter and stiffness positively correlated with GAG and type II collagen accretion. Matrix production in beads is supported by the use of a rotary bioreactor.