In vivo implantation of a tissue engineered stem cell seeded hemi-laryngeal replacement maintains airway, phonation, and swallowing in pigs

Tissue-Engineered Implant for Hemilaryngectomy Reconstruction with Recurrent Laryngeal Nerve Injury

OBJECTIVE

Laryngeal cancer resections often require excision of portions of the larynx along with sacrifice of the ipsilateral recurrent laryngeal nerve (RLN). In such cases, there are no reconstructive options that reliably restore laryngeal function, rendering patients with severe functional impairment. To address this unmet clinical need, we extend our evaluation of a 3-implant mucosal, muscle, cartilage reconstruction approach aimed at promoting functional laryngeal restoration in a porcine hemilaryngectomy model with ipsilateral RLN transection.

METHODS

Six Yucatan mini-pigs underwent full-thickness hemilaryngectomies with RLN transection followed by transmural reconstruction using fabricated collagen polymeric mucosal, muscle, and cartilage replacements. To determine the effect of adding therapeutic cell populations, subsets of animals received collagen muscle implants containing motor-endplate-expressing muscle progenitor cells (MEEs) and/or collagen cartilage implants containing adipose stem cell (ASC)-derived chondrocyte-like cells. Acoustic vocalization and laryngeal electromyography (L-EMG) provided functional assessments and histopathological analysis with immunostaining was used to characterize the tissue response.

RESULTS

Five of six animals survived the 4-week postoperative period with weight gain, airway maintenance, and audible phonation. No tracheostomy or feeding tube was required. Gross and histological assessments of all animals revealed implant integration and regenerative remodeling of airway mucosa epithelium, muscle, and cartilage in the absence of a material-mediated foreign body reaction or biodegradation. Early voice and L-EMG data were suggestive of positive functional outcomes.

CONCLUSION

Laryngeal reconstruction with collagen polymeric mucosa, muscle, and cartilage replacements may provide effective restoration of function after hemilaryngectomy with RLN transection. Future preclinical studies should focus on long-term functional outcomes.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Global Bibliometric and Visualized Analysis of Tracheal Tissue Engineering Research

The development of tracheal tissue engineering (TTE) has seen a rapid growth in recent years. The purpose of this study was to investigate the global status, trends, and hotspots of TTE research based on bibliometrics and visualization analysis. Publications related to TTE were retrieved and included in the Web of Science Core Collection. VOSviewer and CiteSpace were used to generate knowledge maps. Six hundred fifty-five publications were identified, and the quantity of the annual publications worldwide was on the increase. International collaboration is a widespread reality. The United States led the world in the field of trachea tissue engineering, whereas University College London was the institution with the greatest contribution. In addition, Biomaterials had a great influence in this field, attracting the largest number of papers. Moreover, the topics of TTE research largely concentrated on the biomechanical scaffold preparation, the vascularization and epithelialization of scaffold, the tracheal cartilage regeneration, and the tissue-engineered tracheal transplantation. And the research on the application of decellularization and 3D printing for the construction of a tissue-engineered trachea was likely to receive more widespread attention in the future. Impact statement In recent years, tracheal tissue engineering (TTE) has experienced rapid growth. In this study, we investigated the worldwide status and trends of TTE research, and revealed the countries, institutions, journals, and authors that had made significant contributions to the field of TTE. Moreover, the possible research hotspots in the future were predicted. According to our research, researchers can gain a better understanding of the trends in this field, and stay informed of the most current research by tracking key journals, institutions, and authors.

Construction of Integral Decellularized Cartilage Using a Novel Hydrostatic Pressure Bioreactor

The decellularized extracellular matrix (ECM) of cartilage is a widely used natural bioscaffold for constructing tissue-engineered cartilage due to its good biocompatibility and regeneration properties. However, current decellularization methods for accessing decellularized cartilaginous tissues require multiple steps and a relatively long duration to produce decellularized cartilage. In addition, most decellularization strategies lead to damage of the microstructure and loss of functional components of the cartilaginous matrix. In this study, a novel decellularization strategy based on a hydrostatic pressure (HP) bioreactor was introduced, which aimed to improve the efficiency of producing integral decellularized cartilage pieces by combining physical and chemical decellularization methods in a perfusing manner. Two types of cartilaginous tissues, auricular cartilage (AC) and nucleus pulposus (NP) fibrocartilage, were selected for comparison of the effects of ordinary, positive, and negative HP-based decellularization according to the cell clearance ratio, microstructural changes, ECM components, and mechanical properties. The results indicated that applying positive HP improved the efficiency of producing decellularized AC, but no significant differences in decellularization efficiency were found between the ordinary and negative HP-treated groups. However, compared with the ordinary HP treatment, the application of the positive or negative HP did not affect the efficiency of decellularized NP productions. Moreover, neither positive nor negative HP influenced the preservation of the microstructure and components of the AC matrix. However, applying negative HP disarranged the fibril distribution of the NP matrix and reduced glycosaminoglycans and collagen type II contents, two essential ECM components. In addition, the positive HP was beneficial for maintaining the mechanical properties of decellularized cartilage. The recellularization experiments also verified the good biocompatibility of the decellularized cartilage produced by the present bioreactor-based decellularization method under positive HP. Overall, applying positive HP-based decellularization resulted in a superior effect on the production of close-to-natural scaffolds for cartilage tissue engineering. Impact statement In this study, we successfully constructed a novel hydrostatic pressure (HP) bioreactor and used this equipment to produce decellularized cartilage by combining physical and chemical decellularization methods in a perfusing manner. We found that positive HP-based decellularization could improve the production efficiency of integral decellularized cartilage pieces and promote the maintenance of matrix components and mechanical properties. This new decellularization strategy exhibited a superior effect in the production of close-to-natural scaffolds and positively impacts cartilage tissue engineering.

Effect of amniotic membrane/collagen scaffolds on laryngeal cartilage repair

Objectives

Laryngeal cartilage defects are a major problem that greatly impacts structural integrity and function. Cartilage repair is also a challenging issue. This study evaluated the efficacy of a collagen scaffold enveloped by amniotic membrane (AM/C) on laryngeal cartilage repair.

Study Design

Experimental animal study.

Methods

Fourteen Dutch rabbits were enrolled in the study. A 5 mm cartilage defect was created in the right and left thyroid lamina. The animals were divided into two groups randomly. Group 1 collagen scaffolds and group 2 AM/C were applied to the right side defects. Left side defects were not repaired, serving as control. Histologic evaluation was done 45 and 90 days following collagen and AM/C application with criteria of tissue and cell morphology, lacuna formation, vascularization, and inflammation.

Results

Significant improvement in cartilage repair was observed in the AM/C side compared to the control side in all histologic criteria after 45 days (p<.05). After 90 days, cartilage repair improved in cell morphology, lacuna formation, and inflammation significantly (p<.05).

Conclusion

The combination of amniotic membrane and collagen scaffolds provides a promising treatment modality for improving the repair of laryngeal cartilage defects.

Level of Evidence

NA.

Tissue-engineered vocal fold replacement in swine: Methods for functional and structural analysis

We have developed a cell-based outer vocal fold replacement (COVR) as a potential therapy to improve voice quality after vocal fold (VF) injury, radiation, or tumor resection. The COVR consists of multipotent human adipose-derived stem cells (hASC) embedded within a three-dimensional fibrin scaffold that resembles vocal fold epithelium and lamina propria layers. Previous work has shown improved wound healing in rabbit studies. In this pilot study in pigs, we sought to develop methods for large animal implantation and phonatory assessment. Feasibility, safety, and structural and functional outcomes of the COVR implant are described. Of eight pigs studied, six animals underwent COVR implantation with harvest between 2 weeks and 6 months. Recovery of laryngeal tissue structure was assessed by vibratory and histologic analyses. Recovery of voice function was assessed by investigating acoustic parameters that were derived specifically for pigs. Results showed improved lamina propria qualities relative to an injured control animal at 6 months. Acoustic parameters reflected voice worsening immediately after surgery as expected; acoustics displayed clear voice recovery in the animal followed for 6 months after COVR. These methods form the basis for a larger-scale long-term pre-clinical safety and efficacy study.

Characterization of a decellularized rat larynx: comparison between microscopy techniques

BACKGROUND

No effective method has yet been developed to efficiently reconstruct the larynx and restore its function. Decellularization has recently been tested for this purpose with very promising results. The goal of decellularization is to remove cells leaving an intact scaffold made of an extracellular matrix (ECM). Although the use of hematoxylin/eosin and Masson trichrome stains is widely accepted to highlight tissue structure, the methods based on evaluation of collagen and elastin are considered highly variable. The aim of this study was to develop a whole organ decellularization protocol and compare the qualitative and quantitative efficiency of some microscopy techniques for collagen and elastin detection in paraffin-embedded tissues.

METHODS

H&E, Masson Trichrome and DAPI staining as well as DNA quantification were used to evaluate decellularization efficiency. Van Gieson stain, Picrosirius Red stain (PRS) and multiphoton laser scanning microscopy (MPM) were carried out for collagen detection and quantitative assessment. Polarized PRS was used to investigate collagen network, and Weigert stain and MPM were used to detect and estimate elastin content.

RESULTS

The decellularization process removed the cellular components without affecting glycosaminoglycan, collagen and elastin content. Concerning collagen quantification, Van Gieson stain underestimated collagen content, while PRS, apparently less fading, did not reach reliable results when used as quantitative method. MPM effectively quantified collagen content. Collagen fibers were visualized much better under polarized light microscopy, allowing to underline that decellularization process affects the homogeneity of 3D collagen network. Concerning elastin detection, Weigert stain and MPM produced overlapping results.

CONCLUSIONS

An efficient protocol to decellularize the whole larynx was developed, allowing the removal of cells without affecting ECM integrity. The results supported the use of non-polarized PRS to highlight collagen, even the thin fibers, second harmonic generation for major fibrillar collagens and polarized PRS for 3D collagen network. Concerning elastin, Weigert stain and MPM showed similar results, thus the use of MPM, rather than that of the Weigert stain, may be suitable to avoid the additional time and costs of a histological staining.

Biocompatible Materials in Otorhinolaryngology and Their Antibacterial Properties

For decades, biomaterials have been commonly used in medicine for the replacement of human body tissue, precise drug-delivery systems, or as parts of medical devices that are essential for some treatment methods. Due to rapid progress in the field of new materials, updates on the state of knowledge about biomaterials are frequently needed. This article describes the clinical application of different types of biomaterials in the field of otorhinolaryngology, i.e., head and neck surgery, focusing on their antimicrobial properties. The variety of their applications includes cochlear implants, middle ear prostheses, voice prostheses, materials for osteosynthesis, and nasal packing after nasal/paranasal sinuses surgery. Ceramics, such as as hydroxyapatite, zirconia, or metals and metal alloys, still have applications in the head and neck region. Tissue engineering scaffolds and drug-eluting materials, such as polymers and polymer-based composites, are becoming more common. The restoration of life tissue and the ability to prevent microbial colonization should be taken into consideration when designing the materials to be used for implant production. The authors of this paper have reviewed publications available in PubMed from the last five years about the recent progress in this topic but also establish the state of knowledge of the most common application of biomaterials over the last few decades.

A Tissue Engineered Construct for Laryngeal Regeneration: A Proof-of-Concept Device Design Study

OBJECTIVES/HYPOTHESIS

Develop a patient-specific tissue engineered construct for laryngeal reconstruction following a partial laryngectomy.

STUDY DESIGN

Bench and animal research.

METHODS

A construct made from a porous polyethylene scaffold shaped in a canine-specific configuration and seeded with autologous canine adipose-derived stem cells in fibrin glue was implanted in a canine following a partial laryngectomy. After 1 year, the construct was first evaluated in vivo with high-speed imaging and acoustic-aerodynamic measures. It was then explanted and evaluated histologically.

RESULTS

The canine study at 1 year revealed the construct provided voicing (barking) with acoustic and aerodynamic measures within normal ranges. The canine was able to eat and breathe normally without long-term support. The construct was integrated with epithelialization of all areas except the medial portion of the vocal fold structure. No anti-infective agents were needed after the standard perioperative medications were completed.

CONCLUSION

This study provided a successful first step toward developing a patient-specific composite construct for patients undergoing partial laryngectomies.

LEVEL OF EVIDENCE

Not Applicable Laryngoscope, 2022.

Differentiation Behaviour of Adipose-Derived Stromal Cells (ASCs) Seeded on Polyurethane-Fibrin Scaffolds In Vitro and In Vivo

Adipose-derived stromal cells (ASCs) are a promising cell source for tissue engineering and regenerative medicine approaches for cartilage replacement. For chondrogenic differentiation, human (h)ASCs were seeded on three-dimensional polyurethane (PU) fibrin composites and induced with a chondrogenic differentiation medium containing TGF-ß3, BMP-6, and IGF-1 in various combinations. In addition, in vitro predifferentiated cell-seeded constructs were implanted into auricular cartilage defects of New Zealand White Rabbits for 4 and 12 weeks. Histological, immunohistochemical, and RT-PCR analyses were performed on the constructs maintained in vitro to determine extracellular matrix (ECM) deposition and expression of specific cartilage markers. Chondrogenic differentiated constructs showed a uniform distribution of cells and ECM proteins. RT-PCR showed increased gene expression of collagen II, collagen X, and aggrecan and nearly stable expression of SOX-9 and collagen I. Rabbit (r)ASC-seeded PU-fibrin composites implanted in ear cartilage defects of New Zealand White Rabbits showed deposition of ECM with structures resembling cartilage lacunae by Alcian blue staining. However, extracellular calcium deposition became detectable over the course of 12 weeks. RT-PCR showed evidence of endochondral ossification during the time course with the expression of specific marker genes (collagen X and RUNX-2). In conclusion, hASCs show chondrogenic differentiation capacity in vitro with the expression of specific marker genes and deposition of cartilage-specific ECM proteins. After implantation of predifferentiated rASC-seeded PU-fibrin scaffolds into a cartilage defect, the constructs undergo the route of endochondral ossification.

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.

Tissue engineering of the larynx: A contemporary review

Objective

Tissue engineering has been a topic of extensive research in recent years and has been applied to the regeneration and restoration of many organs including the larynx. Currently, research investigating tissue engineering of the larynx is either ongoing or in the preclinical trial stage.

Methods

A literature search was performed on the Advanced search field of PubMed using the keywords: “(laryncheal tissue engineering) AND (cartilage regeneration OR scaffolds OR stem cells OR biomolecules).” After applying the selection criteria, 65 articles were included in the study.

Results

The present review focuses on the rapidly expanding field of tissue‐engineered larynx, which aims to provide stem cell–based scaffolds combined with biological active factors such as growth factors for larynx reconstruction and regeneration. The trend in recent studies is to use new techniques for scaffold construction, such as 3D printing, are developed. All of these strategies have been instrumental in guiding optimization of the tissue‐engineered larynx, leading to a level of clinical induction beyond the in vivo animal experimental phase.

Conclusions

This review summarizes the current progress and outlines the necessary basic components of regenerative laryngeal medicine in preclinical fields. Finally, it considers the design of scaffolds, support of growth factors, and cell therapies toward potential clinical application.

Tissue engineering applications in otolaryngology-The state of translation

While tissue engineering holds significant potential to address current limitations in reconstructive surgery of the head and neck, few constructs have made their way into routine clinical use. In this review, we aim to appraise the state of head and neck tissue engineering over the past five years, with a specific focus on otologic, nasal, craniofacial bone, and laryngotracheal applications. A comprehensive scoping search of the PubMed database was performed and over 2000 article hits were returned with 290 articles included in the final review. These publications have addressed the hallmark characteristics of tissue engineering (cellular source, scaffold, and growth signaling) for head and neck anatomical sites. While there have been promising reports of effective tissue engineered interventions in small groups of human patients, the majority of research remains constrained to in vitro and in vivo studies aimed at furthering the understanding of the biological processes involved in tissue engineering. Further, differences in functional and cosmetic properties of the ear, nose, airway, and craniofacial bone affect the emphasis of investigation at each site. While otolaryngologists currently play a role in tissue engineering translational research, continued multidisciplinary efforts will likely be required to push the state of translation towards tissue-engineered constructs available for routine clinical use.

LEVEL OF EVIDENCE

NA.

Limitations of recellularized biological scaffolds for human transplantation

A shortage of donor organs for transplantation and the dependence of the recipients on immunosuppressive therapy have motivated researchers to consider alternative regenerative approaches. The answer may reside in acellular scaffolds generated from cadaveric human and animal tissues. Acellular scaffolds are expected to preserve the architectural and mechanical properties of the original organ, permitting cell attachment, growth, and differentiation. Although theoretically, the use of acellular scaffolds for transplantation should pose no threat to the recipient's immune system, experimental data have revealed significant immune responses to allogeneic and xenogeneic transplanted scaffolds. Herein, we review the various factors of the scaffold that could trigger an inflammatory and/or immune response, thereby compromising its use for human transplant therapy. In addition, we provide an overview of the major cell types that have been considered for recellularization of the scaffold and their potential contribution to triggering an immune response.

Motor endplate-expressing cartilage-muscle implants for reconstruction of a denervated hemilarynx

OBJECTIVE

Tissue engineering of the larynx requires a complex, multiple tissue layer design. Additionally, spontaneous reinnervation of the larynx after recurrent laryngeal nerve (RLN) injury is often disorganized, resulting in subpar function. This study investigates use of tissue-engineered cartilage and motor endplate-expressing (MEE) tissue-engineered skeletal muscle implants for laryngeal reconstruction and the promotion of organized reinnervation after RLN injury.

METHODS

F344 rat primary muscle progenitor cells (MPCs) were isolated. Three-dimensional muscle constructs were created by encapsulating MPCs in type I oligomeric collagen under passive tension. Constructs were then cultured in differentiation medium (MPC control constructs) or induced to form motor endplates (MEE constructs) with neurotrophic agents. Three-dimensional cartilage constructs were created with adipose stem cells differentiated in chondrocyte medium. The muscle and cartilage constructs were implanted into surgically created myochondral defects in the F344 rat larynx with injured or intact (control) RLN. At 1-, 3-, and 6-month timepoints, videolaryngoscopy, electromyography (EMG), histology, and immunohistochemistry were used to assess outcomes.

RESULTS

At all timepoints, cartilage-muscle implants were well integrated into host tissue. Functionally, there was increased vocal fold adduction and EMG activity in nerve-injured rats treated with the MEE constructs when compared to those treated with the MPC control constructs. Motor endplate-expressing constructs had increased myofiber cross-sectional area compared to MPC control constructs.

CONCLUSION

Although our laboratory previously demonstrated that muscle and cartilage constructs could be used separately for hemilaryngeal reconstruction, this study suggests combining them with the modification of MEEs rather than MPCs, resulting in improved muscle recovery after recurrent laryngeal nerve injury.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:1293-1300, 2019.