Immunosuppressive protocols after laryngeal transplantation: a systematic review.

BACKGROUNDS: Larynx transplantation has been successfully performed four times, in 1998, 2010, 2015 and 2023 remained the ultimate goal of voice, feeding and breathing rehabilitation. OBJECTIVE: Immunosuppressive protocols used during the previous successful larynx allotransplantation are detailed. MATERIAL AND METHODS: A systematic review of the literature on PUBMED/Medline, Cochrane and Embase was conducted. Articles relating to actual human larynx transplantations were included. RESULTS: Bibliography search gathered N = 10 publications related to the performance and follow-up of human laryngeal transplantations. N = 8 publications were included corresponding to N = 3 actual human larynx transplantations performed in 1998 and 2010 in the USA and in 2015 in Poland. Immunosuppression protocols, induction and maintenance strategies, rejection monitoring and history of all the three previous laryngeal grafts were detailed. CONCLUSIONS: Beyond the surgical prowess, larynx transplantation is feasible and associated with a reasonably successful outcome when compared to other solid organ transplants. Immunosuppressive regimen protocols and technologies for the monitoring of the organ viability have evolved. SIGNIFICANCE: The reevaluation of this surgical option serves as the reminder of the critical necessity to implement a meticulous immunosuppression protocol when transplanting this inherently immunogenic composite organ, the larynx.

Laryngeal Transplantation.

Laryngeal transplantation offers the hope of replacing voice and laryngeal function in patients with debilitating laryngeal injuries or loss of the larynx from trauma or oncologic reasons. Our group at UC Davis performed a laryngotracheal transplantation, and our experience is reviewed in this chapter. The indications, challenges, and limitations of this procedure are highlighted, and the world's other published cases are reviewed.

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.

First Complex Allotransplantation of Neck Organs: Larynx, Trachea, Pharynx, Esophagus, Thyroid, Parathyroid Glands, and Anterior Cervical Wall: A Case Report.

OBJECTIVE: Evaluate the possibility of performing a complex vascular allotransplant of all neck organs including skin. SUMMARY BACKGROUND DATA: There are 2 previous attempts described in the literature, none of them being that complex. The first one is nonfunctional due to chronic rejection, the second one is viable yet considerably limited in complexity (no parathyroids, no skin). METHODS: The allotransplantation was performed simultaneously on 2 adjacent operating rooms, using microsurgical techniques. RESULTS: The patient's voice, breathing through mouth, swallowing, and endocrinal functions have been fully restored. CONCLUSIONS: Achieved results show clearly that such operations performed in selected patients can nearly fully restore functional and aesthetic effects in 1 single procedure.

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

OBJECTIVES: Human laryngeal allotransplantation has long been contemplated as a surgical option following laryngectomy, but there is a paucity of information regarding the indications, surgical procedure, and patient outcomes. Our objectives were to identify all human laryngeal allotransplants that have been undertaken and reported in the English literature and to evaluate the success of the procedure. DATA SOURCES: MEDLINE, Embase, Current Index to Nursing and Allied Health Literature, Web of Science and Scopus, and the Gray literature. REVIEW METHODS: A comprehensive search strategy was undertaken across multiple databases. Inclusion criteria were case reports of patients who had undergone human laryngeal allotransplantation. Information regarding indications, operative techniques, complications, graft viability, and functional outcomes were extracted. RESULTS: A total of 5,961 articles, following removal of duplicates, matched the search criteria and were screened, with five case reports relating to two patients, ultimately fulfilling the entry criteria. CONCLUSIONS: Two laryngeal transplants have been reported in the medical literature. Although both patients report improved quality of life relating to their ability to communicate with voice, further research is necessary to shape our understanding of this complicated operation, its indications, and its functional outcomes. Laryngoscope, 127:1861-1868, 2017.

Stem Cell-Based Tissue-Engineered Laryngeal Replacement.

Patients with laryngeal disorders may have severe morbidity relating to swallowing, vocalization, and respiratory function, for which conventional therapies are suboptimal. A tissue-engineered approach would aim to restore the vocal folds and maintain respiratory function while limiting the extent of scarring in the regenerated tissue. Under Good Laboratory Practice conditions, we decellularized porcine larynges, using detergents and enzymes under negative pressure to produce an acellular scaffold comprising cartilage, muscle, and mucosa. To assess safety and functionality before clinical trials, a decellularized hemilarynx seeded with human bone marrow-derived mesenchymal stem cells and a tissue-engineered oral mucosal sheet was implanted orthotopically into six pigs. The seeded grafts were left in situ for 6 months and assessed using computed tomography imaging, bronchoscopy, and mucosal brushings, together with vocal recording and histological analysis on explantation. The graft caused no adverse respiratory function, nor did it impact swallowing or vocalization. Rudimentary vocal folds covered by contiguous epithelium were easily identifiable. In conclusion, the proposed tissue-engineered approach represents a viable alternative treatment for laryngeal defects. Stem Cells Translational Medicine 2017;6:677-687.

A murine model of subglottic granulation.

OBJECTIVE: This study aimed to develop a functional model of subglottic stenosis by inducing direct airway irritation in transplanted mouse laryngotracheal complexes. METHODS: Laryngotracheal complexes from C57BL/6 mice were harvested and divided into three groups: uninjured, mechanically injured and chemically injured. Donor laryngotracheal complexes from each group were placed in dorsal subcutaneous pockets of recipient mice. Each week, the transplanted laryngotracheal complexes were harvested, and tissues were fixed, sectioned, and stained with haematoxylin and eosin. Representative slides were reviewed by a blinded pathologist, to determine the formation of granulation tissue, and graded as to the degree of granulation formation. RESULTS: Direct airway irritation induced granulation tissue formation under the disrupted epithelium of airway mucosa; this was seen as early as two weeks after chemical injury. CONCLUSION: Results indicate that granulation tissue formation in a murine model may be an efficient tool for investigating the development and treatment of subglottic stenosis.

What is the future of 'organ transplantation' in the head and neck?

PURPOSE OF REVIEW: To update readers on the current state and future of head and neck tissue transplantation. RECENT FINDINGS: Many exciting advances have recently occurred in the field of head and neck transplantation and regenerative medicine. Larynx, face, and trachea transplants have all been successfully performed. Significant advancements in tissue engineering have occurred, including the ability to generate three-dimensional tissue structures. Transplantation of regenerated tissues has been successfully incorporated into airway reconstruction. SUMMARY: These exciting advancements set the foundation to expand reconstructive options for dysfunctional tissues and to improve a patient's quality of life.

Airway tissue engineering: an update.

INTRODUCTION: Prosthetic materials, autologous tissues, cryopreserved homografts and allogeneic tissues have thus far proven unsuccessful in providing long-term functional solutions to extensive upper airway disease and damage. Research is therefore focusing on the rapidly expanding fields of regenerative medicine and tissue engineering in order to provide stem cell-based constructs for airway reconstruction, substitution and/or regeneration. AREAS COVERED: Advances in stem cell technology, biomaterials and growth factor interactions have been instrumental in guiding optimization of tissue-engineered airways, leading to several first-in-man studies investigating stem cell-based tissue-engineered tracheal transplants in patients. Here, we summarize current progress, outstanding research questions, as well as future directions within the field. EXPERT OPINION: The complex immune interaction between the transplant and host in vivo is only beginning to be untangled. Recent progress in our understanding of stem cell biology, decellularization techniques, biomaterials and transplantation immunobiology offers the prospect of transplanting airways without the need for lifelong immunosuppression. In addition, progress in airway revascularization, reinnervation and ever-increasingly sophisticated bioreactor design is opening up new avenues for the construction of a tissue-engineered larynx. Finally, 3D printing is a novel technique with the potential to render microscopic control over how cells are incorporated and grown onto the tissue-engineered airway.

Stem cell-based organ replacements-airway and lung tissue engineering.

Tissue engineering requires the use of cells seeded onto scaffolds, often in conjunction with bioactive molecules, to regenerate or replace tissues. Significant advances have been made in recent years within the fields of stem cell biology and biomaterials, leading to some exciting developments in airway tissue engineering, including the first use of stem cell-based tissue-engineered tracheal replacements in humans. In addition, recent advances within the fields of scaffold biology and decellularization offer the potential to transplant patients without the use of immunosuppression.

Prefabrication and prelamination strategies for the reconstruction of complex defects of trachea and larynx.

Complex tracheal and laryngeal defects can be reconstructed using prelamination and prefabrication techniques. Three clinical situations are described in detail in the article. In short segment restenosis defects within scarred surroundings, we restore the fibrocartilaginous defect with a radial forearm fascia flap prelaminated with buccal mucosa or cartilage. This provides a newly vascularized inner lining to the tracheal defect and restores the tubular convexity. For long segment defects we need a technique that can withstand respiratory forces. We use a heterotopic prefabrication strategy to vascularize a tracheal allograft wrapped in forearm fascia. Chimerism is created by replacing donor respiratory epithelium with buccal mucosa of the recipient. After orthotopic transfer, this chimerism allows immunosuppression to be tapered and stopped when bronchoscopy shows mucosal integrity of the new trachea, since the recipient epithelium replaces the allogeneic inner tracheal lining by means of a chronic rejection process. A distinct situation occurs after resection of a unilateral larynx tumor, which usually results in a total laryngectomy with loss of both vocal cords, since reconstruction of the hemilarynx is considered too complex. First, we prefabricate a nearby four-ring autologous tracheal segment using radial forearm fascia. In a second stage, this orthotopically vascularized trachea restores the laryngeal structure with the aim to conserve one vocal cord and thus speech. Orthotopic and heterotopic prelamination and prefabrication strategies offer efficient and reproducible solutions for the restoration of challenging short and long segment tracheal defects, as well as unilateral laryngeal defects. The series in this review article are based on previous studies and case reports. The level of evidence is III-"Study of nonconsecutive patients, without a universally applied gold standard: case-control study".

Total laryngeal transplant explanted: 14 years of lessons learned.

In 1998, the first successful total laryngeal transplant was performed. Outstanding voice quality and swallowing function were achieved, and over the subsequent 14 years, much was learned about tolerance of a transplanted larynx. After approximately a decade, a slowly progressive, chronic rejection process gradually rendered the organ nonfunctional, and the patient and his providers deemed him appropriate for explantation. This is a report of the clinical indications and outcome surrounding the explantation of the first successful total laryngeal transplant.

Laryngotracheal transplantation: technical modifications and functional outcomes.

OBJECTIVES/HYPOTHESIS: Laryngeal transplantation offers the potential for patients without a larynx to recover their voice, which is critical in our communication age. We report clinical and functional outcomes from a laryngotracheal transplant. Widespread adoption of this technique has been slowed due to the ethical concerns of life-long immunosuppression after a nonvital organ transplant. Our patient was already on immunosuppressive medication from prior kidney-pancreas transplantation, and therefore was not exposed to added long-term risk. We describe the unique technical advances, clinical course, and rehabilitation of this patient and the implications for future laryngeal transplantation. STUDY DESIGN: Case report. METHODS: A laryngotracheal transplantation was performed in a 51-year-old prior kidney-pancreas transplant recipient presenting with complete laryngotracheal stenosis. Surgical modifications were made in the previously described technique related to retrieval, vascular supply, and reinnervation. This resulted in a robustly vascularized organ with well-perfused long-segment tracheal transplant and early return of motor reinnervation. RESULTS: A multidisciplinary approach resulted in a successful transplant without evidence of rejection to date. Postoperatively, the patient continues to rely on a tracheotomy but has had the return of an oral and nasal airway, vocalization, smell, and taste, all experienced for the first time in 11 years. CONCLUSIONS: We have demonstrated that our methods may result in a successful laryngotracheal transplant. We describe the preparation, surgical technique, rehabilitation, and interventions employed in achieving optimal outcomes. This report contributes valuable information on this rarely performed composite transplant.

Laryngeal transplantation in minipigs: early immunological outcomes.

Despite recent tissue-engineering advances, there is no effective way of replacing all the functions of the larynx in those requiring laryngectomy. A recent clinical transplant was a success. Using quantitative immunofluorescence targeted at immunologically relevant molecules, we have studied the early (48 h and 1 week) immunological responses within larynxes transplantated between seven pairs of National Institutes of Health (NIH) minipigs fully homozygous at the major histocompatibility complex (MHC) locus. There were only small changes in expression of some molecules (relative to interindividual variation) and these were clearest in samples from the subglottic region, where the areas of co-expression of CD25(+) CD45RC(-) CD8(-) and of CD163(+) CD172(+) MHC-II(-) increased at 1 week after transplant. In one case, infiltration by recipient T cells was analysed by T cell receptor (TCR) Vß spectratype analysis; this suggested that changes in the T cell repertoire occur in the donor subglottis mucosal tissues from day 0 to day 7, but that the donor and recipient mucosal Vß repertoires remain distinct. The observed lack of strong immunological responses to the trauma of surgery and ischaemia provides encouraging evidence to support clinical trials of laryngeal transplantation, and a basis on which to interpret future studies involving mismatches.

[Inhalation anesthesia during spontaneous ventilation in a patient with a tracheolaryngeal transplant requiring debridement of fibrous tissue obstructing the lumen]. / Anestesia inhalatoria con preservación de la ventilación espontánea en un paciente trasplantado de laringe y tráquea sometido a desbridamiento intraluminal.

Graft stenosis from fibrous granulation tissue is not an uncommon problem in recipients of a transplanted trachea and larynx. We describe the case of a man with a transplanted trachea who was seen for respiratory difficulty and stridor secondary to stenosis. Examination through a rigid bronchoscope and surgical debridement were both performed under anesthesia with sevoflurane alone while the man breathed spontaneously. The outcome of treatment with sequential debridements of fibrotic tissue and autologous stem cell injection was satisfactory and the patient was discharged.

Airway tissue engineering.

INTRODUCTION: Prosthetic replacements, autologous tissue transfer and allografts have so far failed to offer functional solutions for the treatment of long circumferential tracheal defects and loss of a functioning larynx. Interest has therefore turned increasingly to the field of tissue-engineering which applies the principles and methods of bioengineering, material science, cell transplantation and life sciences in an effort to develop in vitro biological substitutes able to restore, maintain or improve tissue and organ function. AREAS COVERED: This article gives an overview of the tissue-engineering approach to airway replacement and will describe the encouraging results obtained so far in tracheal regeneration. The recent advances in the field of tissue-engineering have provided a new attractive approach towards the concept of functional substitutes and may represent an alternative to the shortage of suitable grafts for reconstructive airway surgery. We summarize fundamental questions, as well as future directions in airway tissue engineering. EXPERT OPINION: The replacement of active movement, as would be necessary to replace an entire larynx introduces another order of magnitude of complexity, although progress in this area is starting to bear fruit. In addition, the stem cell field is advancing rapidly, opening new avenues for this type of therapy.

Laryngeal allotransplantation by stages in beagles: an initial study.

OBJECTIVE: To establish a model of cynolaryngeal transplantation. METHODS: Ten beagles, matched for weight (8-10 kg) were divided into five groups for allotransplantation. The vascular circulation was managed with an end-to-end or end-to-lateral anastomosis of allograft bilateral common carotid arteries to recipient bilateral common carotid arteries, and bilateral external jugular veins. The recurrent laryngeal nerve was anastomosed end-to-end. Then, a vascularized allograft was embeded in the cervical subcutaneous tissue of the recipient, and cyclosporine administered every day. RESULTS: The allografts in groups 3, 4, and 5 survived up to 1 month. Groups 1 and 2 showed necrosis and cervical infection. CONCLUSIONS: Beagles accepted laryngeal allotransplantation by stages (laryngeal allograft fore-embed model). Allograft survival was secluded by glandular organ secretion. Immunosuppression must be continuously administered.