Laryngectomees' views on laryngeal transplantation

Immunomodulatory Role of Mesenchymal Stem Cell Therapy in Vascularized Composite Allotransplantation

This review aims to summarize contemporary evidence of the in vitro and in vivo immunomodulatory effects of mesenchymal stem cells (MSCs) in promoting vascularized composite allotransplant (VCA) tolerance. An extensive literature review was performed to identify pertinent articles of merit. Prospective preclinical trials in mammal subjects receiving VCA (or skin allograft) with administration of MSCs were reviewed. Prospective clinical trials with intravascular delivery of MSCs in human populations undergoing solid organ transplant were also identified and reviewed. Sixteen preclinical studies are included. Eleven studies compared MSC monotherapy to no therapy; of these, ten reported improved graft survival, which was statistically significantly prolonged in eight. Eight studies analyzed allograft survival with MSC therapy as an adjunct to proven immunosuppressive regimens. In these studies, daily immunosuppression was transiently delivered and then stopped. In all studies, treatment-free graft survival was statistically significantly prolonged in animals that received MSC therapy. MSCs have been safely administered clinically and their use in renal transplant clinical trials provides evidence that they improve allograft transplant tolerance in clinical practice. There is potential for MSC induction therapy to overcome many of the obstacles to widespread VCA in clinical practice. Preclinical studies are needed before MSC-induced VCA tolerance becomes a clinical reality.

Laryngeal Transplantation

Patients who require laryngectomy usually do not want to completely or partially lose their larynx. Laryngeal transplantation (LT) is a composite tissue transplantation from a cadaver to an alive recipient and requires lifelong immunosuppression in postoperative term. The aims of LT are breathing without tracheostoma, normal swallowing, and voice production. To date, only two successful complete LT have been performed in human despite many researches. The requirement of post-transplant immunosuppressive treatment has ethical concern for the larynx, which is a non-vital organ. However, LT may be an option for improving the quality of life of patients undergoing laryngectomy. In this study, we discussed the LT procedure and researches with the literature.

Laryngeal transplantation in minipigs: vascular, myologic and functional outcomes

There is no effective way of replacing all the functions of the larynx in those requiring laryngectomy. Regenerative medicine offers promise, but cannot presently deliver implants with functioning neuromuscular units. A single well-documented laryngeal transplant in man was a qualified success, but more information is required before clinical trials may be proposed. We studied the early response of the larynx to laryngeal transplantation between 17 pairs of NIH minipigs full matched at the MHC2 locus. Following iterative technical improvements, pigs had good swallowing and a patent airway at 1 week. No significant changes in mucosal blood flux were observed compared with pre-operative measurements. Changes in muscle morphology and fibre phenotype were observed in transplant muscles retrieved after 7 days: the levels of fast and slow myosin heavy chain (MyHC) protein were reduced and embryonic MyHC was up regulated consistent with denervation induced atrophy. At 1 week laryngeal transplantation can result in good swallowing, and is not associated with clinical evidence of ischemia-reperfusion injury in MHC-matched pigs.

Laryngeal transplantation: research, clinical experience, and future goals

The loss of a functional voice because of trauma or laryngectomy can have a devastating impact on a patient's self-esteem and overall quality of life. Unfortunately, even with advances in organ preservation therapy, total laryngectomy is frequently necessary in the treatment of laryngeal carcinoma. Over the past several years, the senior author initiated research into laryngeal transplantation with the goal of restoring lung-powered speech for these patients. The research led to the development of an animal model and several groundbreaking studies in this area. Investigations into the use of irradiation, single-drug and multidrug immunosuppression, and the effects of mammalian target of rapamycin (mTOR) inhibitors have produced significant insight into laryngeal allograft preservation. The laboratory research culminated in the first successful total laryngeal transplant in 1998. The patient had suffered significant laryngeal trauma and strongly desired return of laryngeal phonation. The patient has been maintained on multidrug immunosuppression with minimal difficulties. Now more than 8 years after the procedure, the patient continues to have an excellent voice and dramatically improved quality of life. Recent data suggest that altered immunosuppression schedules and the use of mTOR inhibitors may allow patients to minimize immunosuppression-related adverse effects and ameliorate the risk of developing recurrent or de novo carcinoma. These data, when considered in combination with the progress made over the past 14 years, lead us to believe that the future of laryngeal transplantation is bright.