The current status of human laryngeal transplantation in 2017: A state of the field review

Voice Rehabilitation After Laryngeal Transplantation: Own Experience

BACKGROUND AND PURPOSE

Laryngeal transplantation (LT) remains an infrequently performed procedure due to well-defined and limited medical indications. The challenges include a very complicated surgery, continuous immunosuppressive treatment, as well as post-transplant rehabilitation of voice, speech, and swallowing. The aim of this paper is to describe a model of voice and speech rehabilitation after LT, based on our own experience.

STUDY DESIGN

Observational study.

METHOD

Presented here are the rehabilitation processes of two patients who had previously undergone LT as well as their pre- and postrehabilitation voice outcomes. Both patients underwent voice, speech, and swallowing rehabilitation in the fifth month after LT.

RESULTS

One of the patients had a significant improvement in voice quality. While, the other did not regain his natural, sonorous voice, but he scored very high on a voice self-assessment test.

CONCLUSION

Voice rehabilitation after LT is a complex and long-term process that requires the involvement of a team of specialists. The optimal anatomical conditions restored during surgery, the patient's motivation and the support of professionals make it possible to return to normal verbal communication.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

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.

A New Animal Model of Laryngeal Transplantation

Only three laryngeal transplants have been described in the literature to date, and none of the techniques has enabled a completely satisfactory functional result to be obtained. This article presents a new model of laryngeal transplantation, with quality of revascularisation of the transplant being the principal objective and optimisation of the various steps of the procedure, with the integration of a new reinnervation technique as a secondary objective. We present a preclinical animal study. Three pig larynges removed in vivo underwent allotransplantation according to the same protocol. The quality of the revascularisation was examined immediately after the surgery as well as by endoscopy for one animal on the fourth day after the operation. The mean time of cold ischaemia was 3 h 15 min. The anaesthetic tolerance of the pigs was excellent. Revascularisation was achieved and judged to be excellent for the three transplants immediately after the operation and the endoscopy performed for one pig on the fourth day after the operation confirmed this result. The anatomical similarities also enabled the application and integration of an innovative technique of laryngeal reinnervation into the various phases of the operation. We describe a reliable and reproducible animal model for laryngeal transplantation. Its application in humans can be envisaged.

Induction of Endotoxin Tolerance Delays Acute Rejection in a Hindlimb Transplantation Model in Rats

BACKGROUND

Acute rejection is seen in 85 percent of composite vascular allogeneic transplants despite long-term immunosuppression. Recently, it was reported that the induction of endotoxin tolerance prolonged heart allograft survival in mice. However, it produced side effects in all the animals secondary to the inflammatory reaction. Galactomannan has shown endotoxin tolerance without this side effect in vitro. The authors hypothesized that galactomannan-induced endotoxin tolerance delays acute rejection in vascular allogeneic transplantation without the side effects produced by lipopolysaccharide.

METHODS

Twenty-four rat hindlimb transplants were divided into four groups according to the preconditioning received: control, lipopolysaccharide (0.16 ml/kg), galactomannan 72 hours before (galactomannan-72) (8 ml/kg), and galactomannan 24 hours before (galactomannan-24) (8 ml/kg). Median acute rejection time, weight loss, and diarrheal episodes were monitored. Blood samples were collected at 0, 7, 21, 30, 45, and 60 days. Plasma cytokines (i.e., tumor necrosis factor alpha, interferon gamma), peripheral chimerism, and lymphocyte percentages were analyzed.

RESULTS

Median allograft survival was 40 days (range, 40 to 44 days) in the control group, 68 days (range, 61 to 71 days) in the lipopolysaccharide group, and 70 days (range, 69 to 73 days) in both galactomannan groups (p = 0.001). Weight loss was higher in the lipopolysaccharide group (p < 0.001), as was the 83.3 percent rate of diarrheal episodes (control, 0 percent, p = 0.015; galactomannan-72, 0 percent, p = 0.015; and galactomannan-24, 16.7 percent, p = 0.02). Preconditioned rats had higher peripheral blood chimerism (lipopolysaccharide, 2.30 ± 0.13 percent; galactomannan-72, 2.63 ±1.46 percent; and galactomannan-24, 2.47 ± 0.19 percent) compared to the control group (2.06 ± 0.36 percent) (lipopolysaccharide, p = 0.04; galactomannan-72, p = 0.002; and galactomannan-24, p = 0.002).

CONCLUSIONS

Induction of endotoxin tolerance delays acute rejection in the rat hindlimb transplantation model. Galactomannan preconditioning has no lipopolysaccharide side effects and was equally effective in delaying acute rejection.

CLINICAL RELEVANCE STATEMENT

The contributions of this experimental work are very incipient. Although the use of galactomannan in clinical practice requires more studies to assess its safety, there is no doubt that immunomodulation may be one of the responses that solve the problem of long-term immunosuppression.

Perfusion-Decellularized Larynx as a Natural 3D Scaffold in a Rabbit Model

INTRODUCTION

Decellularized larynges could be used as scaffolds to regenerate the larynx. The purpose of this study was to establish a perfusion decellularization protocol to produce a 3-dimensional whole laryngeal extracellular matrix (ECM) scaffold in a rabbit model.

METHODS

The larynges of 20 rabbits assigned to the study group were harvested and decellularized using a perfusion decellularization protocol, while the larynges of 10 rabbits in the control group were harvested and untreated. Macroscopic and microscopic morphological analyses, a molecular analysis, a cellular content analysis, and scanning electron microscopy were performed.

RESULTS

A histological analysis showed the absence of cellular components, the presence of the ECM, and an intact cartilage structure filled with chondrocytes. The mean total DNA amounts of the native larynx, decellularized larynx, and decellularized cartilage-free larynx were 1,826.40, 434.70, and 41.40 μg/µL, respectively; those for the decellularized larynx and decellularized cartilage-free larynx were significantly lower (p < 0.001 and p < 0.001, respectively). The total amount of DNA in the decellularized sample was significantly lower compared to that in the native sample, at 57.2% in cartilage (p < 0.001), 2.4% in the thyroid gland (p < 0.001), 2.7% in muscle (p < 0.001), 1.6% in vessels (p < 0.001), and 4.8% in the vocal cords (p < 0.001).

CONCLUSION

Our perfusion decellularization protocol is feasible and reproducible to produce a 3-dimensional whole laryngeal ECM scaffold in a rabbit.

Large Animal Models of Vascularized Composite Allotransplantation: A Review of Immune Strategies to Improve Allograft Outcomes

Over the past twenty years, significant technical strides have been made in the area of vascularized composite tissue allotransplantation (VCA). As in solid organ transplantation, the allogeneic immune response remains a significant barrier to long-term VCA survival and function. Strategies to overcome acute and chronic rejection, minimize immunosuppression and prolong VCA survival have important clinical implications. Historically, large animals have provided a valuable model for testing the clinical translatability of immune modulating approaches in transplantation, including tolerance induction, co-stimulation blockade, cellular therapies, and ex vivo perfusion. Recently, significant advancements have been made in these arenas utilizing large animal VCA models. In this comprehensive review, we highlight recent immune strategies undertaken to improve VCA outcomes with a focus on relevant preclinical large animal models.

Attitudes of Hand Surgeons and Hand Reconstruction Patients Toward Hand Allotransplantation in Taiwan

BACKGROUND

Recent advances in immunosuppressive protocols have increasingly made hand allotransplantation a realistic reconstructive option with more than 100 cases performed worldwide. While attitudes toward allotransplantation have been assessed for North American surgeons and patients alike, similar assessments have previously remained unconducted in Asia in general and Taiwan in specific. This study examines the perceptions of both Taiwanese hand surgeons and hand reconstruction patients.

METHODS

An email-based survey was sent to all active members of the Taiwanese Society for Surgery of the Hand. Surgeon training backgrounds and practice profiles were gathered as well as current beliefs on indications, risks, ethicality, priority of psychosocial issues, and obstacles to implementation. Patients receiving rehabilitation at Chang Gung Memorial Hospital Linkou after severe upper extremity injuries were invited to complete a patient survey. Demographics, injury characteristics, understanding of allotransplantation and immunosuppression, willingness to donate, and willingness to receive transplantation were assessed.

RESULTS

Forty-four hand surgeons responded (24.3% response rate). The majority (61.4%) considered hand allotransplantation to be a high-risk operation, although 40% supported the development of hand allotransplantation under current techniques and immunosuppression. Bilateral hands loss was the most commonly accepted indication for transplant (90.9%), whereas dominant hand loss was less frequently accepted (43.2%). Treatment compliance and functional outcomes were the most frequent psychosocial issues of concern regarding patient counseling. Patient respondents were mostly in the fifth decade of life (29.5%) with at least a high school education (75.0%). Most were aware of the feasibility of hand transplantation (68.2%). Patients were more likely than surgeons to consider nondominant hand, multiple-digit, and thumb-only amputations as indications for transplantation. Functional outcomes and financial considerations were the most frequent patient concerns.

CONCLUSIONS

This study indicates there is support for hand allotransplantation as a solution for limb loss in both hand surgeons and hand patients in Taiwan. This study adds to the lack of knowledge regarding surgeon and patient attitudes toward allotransplantation in Asia, although further work is required to assess the willingness of broader Taiwanese medical to refer candidates and for the general population to donate.

Upper extremity and craniofacial vascularized composite allotransplantation: ethics and immunosuppression

Vascularized composite allotransplantation (VCA) is the name most often used to refer to the transplantation of anatomical units composed of multiple tissue types (skin, bone, muscle, tendon, nerves, vessels, etc.) when such transplants do not have the primary purpose of extending life, as is the case in the more familiar field of solid organ transplantation (SOT). A serious interest in VCA developed in the late twentieth century following advances in immunosuppression which had led to significant improvements in short and medium-term survival among SOT recipients. Several ethical concerns have been raised about VCA, with many being connected in one way or another to the limitations, burdens, and risks associated with immunosuppression. This article will focus on upper extremity and craniofacial VCA, beginning with a brief review of the history of VCA including reported outcomes, followed by a discussion of the range of ethical concerns, before exploring in greater detail how immunological issues inform and shape several of the ethical concerns.

A Call to Accountability: Reporting Outcomes in Vascularized Composite Allotransplantation

Because nearly all the vascularized composite allotransplants performed in the United States have been proposed and carried out as research, the ethical duty to report outcomes pertains. This duty is set forth in several international statements, including the World Health Organization’s Statement on Public Disclosure of Clinical Trial Results, the 2013 Helsinki Declaration, and the Singapore Statement on Research Integrity. These international statements call for the reporting of negative and inconclusive outcomes as well as positive outcomes, and for the reporting of results from previously unreported past research. In 2014, the Organ Procurement and Transplant Network vascularized composite allotransplant committee proposed mandatory data collection and submission requirements for transplants, but only for those which took place in September 2015 or later. Reporting of data for the allotransplants which took place before September 2015 was regarded as optional, even though the pre-September 2015 transplants represent the majority of vascularized composite allotransplants in the United States and all the long-term outcome data. We encourage the American Society of Reconstructive Transplantation and the Organ Procurement and Transplant Network committee to embrace the international ethical standards and to hold all vascularized composite allotransplant programs in the United States accountable for reporting data on outcomes of pre-September 2015 transplants.

Technical, Immunological, and Ethical Similarities and Differences Between Vascularized Composite Allotransplantation and Solid Organ Transplantation in Current Practice

Solid organ transplantation (SOT) is a surgical method used as the gold standard in end-term organ failure. Following SOT, successful results have also been achieved in vascularized composite tissue transplantation, which improves the quality of life with the success of solid organ transplants and the development of modern immunosuppressive regimens. This review discusses the preoperative, operative, postoperative, and immunological differences between vascularized tissue transplantation and SOT.

Functional identification of abductor and adductor branches for laryngeal transplantation

PURPOSE

This is a feasibility study of functional identification of the abductor and adductor recurrent laryngeal nerve branches, which could be used in the donor's larynx for functional laryngeal transplantation.

METHODS

The study was performed on swine (n = 3) and human (n = 4) models of a donor larynx. The recurrent laryngeal nerve and its branches were found. Using stimulator, abductor and adductor branches were identified, and glottis closing and opening were captured with an endoscope.

RESULTS

The result was positive if two ENT specialists noticed at least one adduction and one abduction movement in the same subject. It was obtained in three out of three swine and three out of four humans.

CONCLUSIONS

This study shows a way of reinnervation of a transplanted larynx which might result in a functional organ. It describes the first step of the procedure: functional identification of the abductor and adductor branches of the recurrent laryngeal nerve in the donor before the larynx is excised for transplantation.

[Regeneration - A New Therapeutic Dimension in Otorhinolaryngology]

Regeneration as a therapeutic priniciple and regenerative medicine in general are promising new strategies to add new therapeutic dimensions to our current treatment options. Today, reconstructive surgery, drugs and implants such as the cochlear implant can replace the functions of damaged tissues. In contrast, regenerative therapies aim at the replacement of the damaged tissues themselves while at the same time replacing their lost tissue function. In this review article new technologies such as 3D-bioprinting and the application of decellularised tissues as biomaterials are introduced and explained. A summary of current preclinical and clinical regenerative studies in otorhinolaryngology is complementing these basic aspects.