Regenerative medicine and nasal surgery

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.

Prevention and Management of Complications in Nasal Reconstruction

Nasal reconstruction is a challenging practice with the potential for complications. Surgeons can prevent complications through preoperative optimization of patient factors, refinement of intraoperative surgical techniques, and postoperative surgical and nonsurgical wound care. Preoperatively, optimization of modifiable and recognition of nonmodifiable risk factors is paramount. Intraoperatively, meticulous flap design and surgical technique promote healing. In the postoperative setting, attentive wound care, adjuvant therapies, and close follow-up for consideration of additional procedures enhance outcomes. By anticipating potential complications across perioperative settings, surgeons can prevent common complications in nasal reconstruction and more effectively manage those complications that arise.

Organoids and Their Research Progress in Plastic and Reconstructive Surgery

Organoids are 3D structures generated from stem cells. Their functions and physiological characteristics are similar to those of normal organs. They are used in disease mechanism research, new drug development, organ transplantation and other fields. In recent years, the application of 3D materials in plastic surgery for repairing injuries, filling, tissue reconstruction and regeneration has also been investigated. The PubMed/MEDLINE database was queried to search for animal and human studies published through July of 2022 with search terms related to Organoids, Plastic Surgery, Pluripotent Stem Cells, Bioscaffold, Skin Reconstruction, Bone and Cartilage Regeneration. This review presents stem cells, scaffold materials and methods for the construction of organoids for plastic surgery, and it summarizes their research progress in plastic surgery in recent years.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 .

A dynamic Air Liquid Interface system for in vitro mimicking of the nasal mucosa

The development of an in vitro 3D model for the growth of the nasal mucosa cells can improve the therapy and the study of pathological states for subjects with chronic airway conditions. We have previously characterized a system consisting of a scaffold with an internal channel and a perfusion bioreactor with two independent flows provided by an external and an internal circuit, respectively. In this paper, this system was designed as a model of the nasal cavity, in which cells, grown on the inner surface of the scaffold channel, would be in contact at the same time with both culture medium, supplied by the external circuit, and air, provided with the internal flow. To ensure adequate nutrient supply to the cells in the scaffold channel, the radial diffusion of the culture medium through the porous matrix was evaluated first in qualitative and, then, in quantitative terms, demonstrating the capability of the system to control the value and direction of this flux. As a preliminary study, the culture of epithelial cells in the scaffold channel is also discussed in static, maintaining the air-liquid-interface (ALI) condition for up to three weeks. Despite minor abnormalities, such as a gap between cell layers and some detachments from the scaffold, the scaffold ensured cell survival and growth during the experimental time. This article is protected by copyright. All rights reserved.

Morphological and Molecular Evaluation of the Tissue Repair following Nasal Septum Biopsy in a Sheep Model

OBJECTIVE

Nasal septal pathologies requiring surgical intervention are common in the population. Additionally, nasal chondrocytes are becoming an important cell source in cartilage tissue engineering strategies for the repair of articular cartilage lesions. These procedures damage the nasal septal cartilage whose healing potential is limited due to its avascular, aneural, and alymphatic nature. Despite the high incidence of various surgical interventions that affect septum cartilage, limited nasal cartilage repair characterizations have been performed to date.

METHODS

To evaluate the healing of the nasal septum cartilage perforation, a septal biopsy was performed in 14 sheep. Two and 6 months later, the tissue formed on the place of perforation was explanted and compared with the native tissue. Tissue morphology, protein and gene expression of explanted tissue was determined using histological, immunohistochemical and real-time quantitative polymerase chain reaction analysis.

RESULTS

Tissue formed on the defect site, 2 and 6 months after the biopsy was characterized as mostly connective tissue with the presence of fibroblastic cells. This newly formed tissue contained no glycosaminoglycans and collagen type II but was positively stained for collagen type I. Cartilage-specific genes COL2, AGG, and COMP were significantly decreased in 2- and 6-month samples compared with the native nasal cartilage. Levels of COL1, COL4, and CRABP1 genes specific for perichondrium and connective tissue were higher in both test group samples in comparison with native cartilage.

CONCLUSIONS

Newly formed tissue was not cartilage but rather fibrous tissue suggesting the role of perichondrium and mucosa in tissue repair after nasal septum injury.

Quitting smoking reverses nasal mucosal changes

BACKGROUND

Smoking, whether active or passive, has proven deleterious effects on the nasal mucosa. There is also a link between smoking and development and/or maintenance of chronic rhinosinusitis (CRS). Reversal of smoking-induced mucosal changes after quitting smoking is still unconfirmed and controversial. The present study investigated the possibility of reversal of smoking-related nasal mucosal changes back to normal after completely quitting smoking.

METHODS

The study was performed on 32 smokers whose nasal mucosa was previously biopsied for electron microscopic examination and then they completely quit smoking. Smoking history of the participants and duration of cessation of smoking were recorded. A tiny 1-mm3 biopsy was taken from the inferior turbinate 1 cm behind its anterior end and processed for electron microscopy. The specimens were processed for electron microscopy and the sections were examined by a pathologist who was blinded to the identity and smoking status of the participant. The results of electron microscopic examination of the nasal mucosa before and after quitting smoking were compared.

RESULTS

The mean duration of quitting smoking was 30.75 months (± 8.26). Examination of the electron microscopic sections before quitting smoking showed variable degrees of loss of cilia and columnar cells, edema between the epithelial cells, few goblet cells, hyperplasia of seromucinous acini, and vascular congestion. The pathologic changes correlated positively with the smoking index of the participant. On the other hand, the sections after quitting smoking showed variable degrees of regeneration of the ciliated cells and decreased vascular congestion. Numerous goblet cells and seromucinous acini were seen. Less pathologic changes were observed with longer durations of cessation of smoking.

CONCLUSIONS

The present study showed an association between smoking and the nasal mucosa. Smoking has several injurious effects on the nasal mucosa. However, the nasal mucosa has excellent regeneration potentials and quitting smoking for sufficient periods of time may reverse these deleterious changes. Considering the established link between smoking and CRS, quitting smoking may help smokers to overcome their recalcitrant disease. This should be further investigated.

Evaluation of human nasal cartilage nonlinear and rate dependent mechanical properties

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

Mechanical, Cellular, and Proteomic Properties of Laryngotracheal Cartilage

The larynx sometimes requires repair and reconstruction due to cancer resection, trauma, stenosis, or developmental disruptions. Bioengineering has provided some scaffolding materials and initial attempts at tissue engineering, especially of the trachea, have been made. The critical issues of providing protection, maintaining a patent airway, and controlling swallowing and phonation, require that the regenerated laryngotracheal cartilages must have mechanical and material properties that closely mimic native tissue. These properties are determined by the cellular and proteomic characteristics of these tissues. However, little is known of these properties for these specific cartilages. This review considers what is known and what issues need to be addressed.

Assessment of Scaffolding Properties for Chondrogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells in Nasal Reconstruction

Importance

Nasal reconstruction in patients who are missing a significant amount of structural nasal support remains a difficult challenge. One challenge is the deficiency of cartilage left within the nose as a consequence of rhinectomy or a midline destructive disease. Historically, the standard donor source for large quantities of native cartilage has been costal cartilage.

Objective

To enable the development of protocols for new mesenchymal stem cell technologies as alternative procedures with reduced donor site morbidity, risk of infection and extrusion.

Design, Setting, and Materials

We examined 6 popular scaffold materials in current practice in terms of their biodegradability in tissue culture, effect on adipose-derived mesenchymal stem cell growth, and chondrogenic fate commitment. Various biomaterials of matching size, porosity, and fiber alignment were synthesized by electrospinning and overlaid with rabbit adipose-derived mesenchymal cells in media supplemented or not with chondrogenic factors. Experiments were performed in vitro using as end points biomarkers for cell growth and chondrogenic differentiation. Polydioxanone (PDO), poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), PHBV-polycaprolactone, poly(L-lactide-co-caprolactone), poly(lactic-co-glycolic acid), and polystyrene scaffolds of 60% to 70% porosity and random fiber alignment were coated with poly(L)-lysine/laminin to promote cell adhesion and incubated for 28 days with 2.5 to 3.5 × 105 rabbit adipose mesenchymal cells.

Main Outcomes and Measures

Cell growth was measured by fluorometric DNA quantitation and chondrogenic differentiation of stem cells by spectrophotometric sulfated glycosaminoglycan (sGAG) assay. Microscopic visualization of cell growth and matrix deposition on formalin-fixed, paraffin-embedded tissue sections was performed, respectively, with nuclear fast red and Alcian blue.

Results

Of 6 scaffold materials tested using rabbit apidose mesenchymal cells, uncoated scaffolds promoted limited cell adhesion but coating with poly(L)-lysine/laminin enabled efficient cell saturation of scaffold surfaces, albeit with limited involvement of scaffold interiors. Similar growth rates were observed under these conditions, based on DNA content analysis. However, PDO and PHBV/PCL scaffolds supported chondrogenic fate commitment better than other materials, based on soluble sGAG analysis and microscopic observation of chondrogenic matrix deposition. The mean (SD) sGAG scaffold values expressed as fold increase over control were PDO, 2.26 (0.88), PHBV/PCL, 2.09 (0.83), PLCL, 1.36 (0.39), PLGA, 1.34 (0.77), PHBV, 1.07 (0.31), and PS, 0.38 (0.14).

Conclusions and Relevance

These results establish materials, reagents, and protocols for tissue engineering for nasal reconstruction using single-layer, chondrogenically differentiated, adipose-derived mesenchymal stem cells. Stackable, scaffold-supported, multisheet bioengineered tissue may be generated using these protocols.

Level of Evidence

NA.

Three-dimensional printing of large nasal septal perforations for optimal prosthetic closure

BACKGROUND

Since 1972, patients with large nasal perforations, who were symptomatic, and who were not candidates for surgery, had the option of custom prosthetic closure at Mayo Clinic. Although septal prostheses have helped many patients, 27% of pre-1982 patients chose not to keep the prosthesis in place. Two-dimensional computed tomography (CT) sizing resulted in more of the patients choosing to retain the prosthesis. The introduction of three-dimensional (3-D) printing to the sizing process offered the potential of further improved retention by refinement in prosthesis fit.

OBJECTIVE

To describe the fabrication of nasal septal prostheses by using 3-D printing for sizing and to compare the retention rate of 3-D-sized prostheses with those that used previous sizing methods.

METHODS

Twenty-one consecutive patients who had placement of septal prostheses sized by using 3-D printed templates were studied. CT image data were used to print 3-D templates of the exact shape of the patient's septal perforation, and medical-grade silastic prostheses were fabricated to fit. In four cases, the 3-D printed template allowed preoperative surgical simulation. Metrics collected included prosthesis retention; symptoms, including intranasal crusting and epistaxis; and previous prosthetic closure failures.

RESULTS

Twenty of the twenty-one patients had improvement in symptoms. The mean diameter of the perforations was 2.4 cm; the mean closure time by the end of the study period was 2.2 years. All but two patients chose to keep their prosthesis in place, for a retention rate of 90%. Seven patients with successful closure had failed previously with prior prosthesis sized without the current 3-D printing methodology. This 90% retention rate exceeded the previous rates before the introduction of 3-D sizing.

CONCLUSION

Sizing done by 3-D printing for prosthetic closure of nasal septal perforations resulted in a higher retention rate in helping patients with these most-challenging nasal septal perforations.