Human laryngeal transplantation: considerations and implications

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.

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.

Preliminary experiences in trachea scaffold tissue engineering with segmental organ decellularization

OBJECTIVES/HYPOTHESIS

Ideal methods for reconstructing the tracheal structure and restoring tracheal function following damage to the trachea or removal of the trachea have not been developed. The purpose of this study is to evaluate the feasibility of using a whole segment decellularized tracheal scaffold to reconstruct the trachea.

STUDY DESIGN

Prospective experimental design.

SETTING

In vivo rabbit model.

METHODS

Trachea scaffolds were created using our previously developed freeze-dry-sonication-sodium dodecyl sulfate (SDS), [FDSS] decellularization process. After histological and mechanical testing, the scaffolds were transplanted orthotopically into segmental defects in New Zealand White Rabbits (n = 9). Another three rabbits receiving the sham operation with autologous trachea transplantations served as the control group. Two weeks after transplantation, the grafts were evaluated endoscopically and histologically.

RESULTS

The mechanical properties of the decellularized trachea segment did not differ significantly from the fresh native trachea. After transplantation, whereas the autograft in the control group showed full integration and functional recovery, all of the rabbits in the decellularized scaffold transplantation group died within 7∼24 days. Although significant collapse of the tracheal tubular structures was noted, full respiratory epithelium regeneration was observed in the rabbits that survived more than 2 weeks.

CONCLUSION

The FDSS decellularization process is effective in creating whole-segment, subtotally decellularized trachea scaffolds. However, although the respiratory epithelium regeneration on the inner surface appeared to be satisfactory, the tubular structures were not able to be maintained after transplantation, which ultimately led to the death of the animals.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:2520-2527, 2016.

The gracilis myocutaneous free flap in swine: an advantageous preclinical model for vascularized composite allograft transplantation research

Vascularized composite allotransplantation (VCA) has become a clinical reality, prompting research aimed at improving the risk-benefit ratio of such transplants. Here, we report our experience with a gracilis myocutaneous free flap in Massachusetts General Hospital miniature swine as a preclinical VCA model. Fourteen animals underwent free transfer of a gracilis myocutaneous flap comprised of the gracilis muscle and overlying skin, each tissue supplied by independent branches of the femoral vessels. End-to-end anastomoses were performed to the common carotid artery and internal jugular vein, or to the femoral vessels of the recipients. Thirteen of fourteen flaps were successful. A single flap was lost due to compromise of venous outflow. This model allows transplantation of a substantial volume of skin, subcutaneous tissue, and muscle. The anatomy is reliable and easily identified and harvest incurs minimal donor morbidity. We find this gracilis myocutaneous flap an excellent pre-clinical model for the study of vascularized composite allotransplantation.

The role of immunophilin ligands in nerve regeneration

Tacrolimus (FK506) is a widely used immunosuppressant in organ transplantation. However, it also has neurotrophic activity that occurs independently of its immunosuppressive effects. Other neurotrophic immunophilin ligands that do not exhibit immunosuppression have subsequently been developed and studied in various models of nerve injury. This article reviews the literature on the use of tacrolimus and other immunophilin ligands in peripheral nerve, cranial nerve and spinal cord injuries. The most convincing evidence of enhanced nerve regeneration is seen with systemic administration of tacrolimus in peripheral nerve injury, although clinical use is limited due to its immunosuppressive side effects. Local tacrolimus delivery to the site of nerve repair in peripheral and cranial nerve injury is less effective but requires further investigation. Tacrolimus can enhance outcomes in nerve allograft reconstruction and accelerates reinnervation of complex functional allograft transplants. Other non-immunosuppressive immunophilins ligands such as V-10367 and FK1706 demonstrate enhanced neuroregeneration in the peripheral nervous system and CNS. Mixed results are found in the application of immunophilin ligands to treat spinal cord injury. Immunophilin ligands have great potential in the treatment of nerve injury, but further preclinical studies are necessary to permit translation into clinical trials.

Past, present, and future prospects for inducing donor-specific transplantation tolerance for composite tissue allotransplantation

Composite tissue allotransplantation (CTA) is among the most immunologically complex and newest transplant fields. Although the field has made considerable advances, there are still concerns that these procedures are performed to enhance quality-of-life issues and are not lifesaving procedures that restore physiologic function. Two challenges limit the widespread application of CTA; the first is chronic rejection, the most prevailing cause of organ allograft failure after transplantation; the second barrier is the numerous health complications associated with lifelong immunosuppressive therapy. Several tolerance-inducing strategies, including costimulatory blockade, T-cell depletion, mixed chimerism, and gene targeting of transplanted organs, have the potential to induce lifelong tolerance to organ allografts without chronic immunosuppression. Effective clinical tolerance protocols that improve CTA acceptance and offer an alternative to the requirement for chronic immunosuppressive therapy could be a major advance in the field. Tolerance would allow allotransplantation to provide a currently unmet need for reconstruction of large tissue defects. This article reviews the history of CTA, current challenges and complications, and offers future directions for CTA research in strategies to induce tolerance.

Chimerism and bone marrow based therapies in transplantation

Composite tissue allotransplantation holds a great potential for providing increased knowledge of anatomy and microsurgical experience for life-enhancing reconstructions. Many transplant cases around the world have made this a clinical reality at the present time. Composite tissue allotransplants contain multiple tissue types, including bone, muscle, vessels, nerves, skin, and immune cells and bear a huge antigenic load. Although immunosuppressive drugs are applied successfully to prevent allograft rejection, their side effects pose a barrier to worldwide use. Bone marrow therapy in many tolerance induction protocols, therefore, provides a guide to reaching the target of permanent immunotolerance. Multiple studies suggest that bone marrow is immunomodulatory and may facilitate allograft acceptance. In this review, bone marrow based therapy protocols of clinical and experimental models are presented in two major categories: solid organ and composite tissue transplantation.

Experimental and clinical experience with small composite tissue allotransplants and cryopreservation techniques

Reconstruction surgery requires imagination, inventiveness, and creation-a quest that entails overcoming obstacles never before encountered. Over the past 25 years, with the advent in microsurgery of free revascularized transfers, it was believed that this fundamental breakthrough would be sufficient to resolve difficulties of whatever nature, and that little else would be necessary. Undoubtedly, the results obtained by using free autotransfers have been so remarkable that it is no longer possible to undertake reconstruction in plastic surgery without fully mastering these techniques. Nevertheless, limitations remain, especially with regard to form and shape, as there are areas where form and function merge. As a result, some clinical cases today continue to induce a sense of powerlessness, as was the case 25 years ago when surgeons were presented with large skin defects that are nowadays treated routinely and with a sense of confidence. The sense of powerlessness today clearly signals that another milepost needs to be reached; we believe this milepost should be allotransplantation. Yet allotransplantation should not remain within the realm of the exceptional; on the contrary, it should become routinely accessible. But in order for it to become so, cryopreservation, a pathway that has so far received little attention, and about which much remains to be learned, should be explored. Accordingly, in this article, we report our experience with xenotransplantation, a mainly clinical procedure in the area of hand surgery.

RAD inhibition of sarcoma growth: implications for laryngeal transplantation

PURPOSE

Laryngeal transplantation has not been widely accepted because of concerns regarding accelerated tumor recurrences in the setting of nonspecific immunosuppression. Allotransplantation could potentially be offered to patients if immunosuppressive therapy could be demonstrated to exert tumor suppressive properties. Preliminary reports have demonstrated an antiproliferative effect of everolimus (RAD), a derivative of the immunosuppressant rapamycin.

MATERIALS AND METHODS

Forty-five 10-week-old inbred C57BL/6N (B6) mice were injected subcutaneously with 1 x 10(6) MCA205 sarcoma cells. On the third postinoculation day, the mice were divided into 4 treatment groups, undergoing daily gavage with RAD at 0, 0.2, 1.0, and 5.0 mg/kg per day for 10 consecutive days. Thereafter, treatment with RAD was discontinued and tumor size was measured every 2 days during treatment and biweekly until sacrifice on the 31st postinoculation day. Whole-blood trough levels (C(min)) were measured for each group.

RESULTS

Mean tumor diameter among the control animals and the mice treated with RAD 0.2 mg/kg per day demonstrated no significant difference (P > .07). Groups treated with RAD 1 and 5 mg/kg per day demonstrated significant growth inhibition between the 7th and the 23rd postinoculation days (P < .0001), with no significant differences being noted between these two groups (P > .09). Mean tumor suppressive whole-blood C(min)'s for the 1 and 5 mg/kg per day groups were 75.6 and 368.9 pg/microL, respectively.

CONCLUSIONS

RAD delivered at immunosuppressive doses of 1 and 5 mg/kg per day resulted in significant growth restriction of a fibrosarcoma in a murine model.

Réalités et perspectives des allotransplantations laryngées

Laryngeal stenosis or amputation for tumor definitely impairs laryngeal functions with negative impact on quality of life. Experimental laryngeal transplantation has been carried out for nearly 40 years hoping that human transplantation would become feasible in the near future. Nearly 10 years ago, a 40 years old man with a long-standing history of recalcitrant laryngeal stenosis, benefited from a vascularized laryngeal allotransplantation. Speech and deglutition resumed quickly making of this first attempt a success. Although a tracheostomy canula and immunosuppressive regimen are still necessary, this man enjoyed a tremendous improvement in this quality of life. Cumulated experiences tend to demonstrate that laryngeal transplantation in human is not only feasible, but may represents the only chance for rehabilitation of number of laryngeal cripple. Induction of a functional tolerance may allow the necessary evaluation of laryngeal allotransplantation in humans.

Developing a Canine Model of Composite Facial/Scalp Allograft Transplantation

The study developed a model of composite facial and scalp allograft transplantation in canines. Dog cadavers were used for anatomy study. Three types of autotransplantations and 2 types of allotransplantations were performed. Cyclosporin A and methylprednisolone or prednisone were given for immunosuppression. Two long-term-surviving dogs with autologous facial transplantation developed leakage of salivary secretions. In the allotransplantation group (n = 5), 1 dog presented rejection at 28 postoperative days but was successfully treated and survived long term (>402 days); 1 dog died of pulmonary infection at 29 postoperative days; 3 dogs survived (>252, >222, and >201 days). Serial electromyelogram studies revealed progressive improvement of the function of the orbicularis oculi muscle. The study indicated that the unilateral superior half of the composite facial and scalp, including one third of the inferior tarsal plate and palpebral conjunctiva (type IV flap) allograft transplantation model, was an ideal model for the study of facial allotransplantation.

[Experimental and clinical experience of composite tissues allotransplantation in reconstructive surgery]

Composite tissue allotransplantation (CTA) is a new concept in reconstructive surgery to improve major physical defects with no current solution. Although not a life-saving procedure, tissue replacement by CTA offers great potential for improving quality of life but relies on lifelong immunotherapy. This new practice has become achievable with the refinement of microsurgical techniques, with experience gained from limb and scalp replantations, with the development of organ transplantation and the release of new immunosuppressive drugs. Experimental and clinical research made it possible. The first human cases of CTA proved the reality and the feasibility of the concept. While the early functional results of these allografts are encouraging, they will need to be assessed in the long-term, and development of less toxic - more efficient immonu-suppressive drugs will be a permanent requisite to the broadening of CTA. Although long-term outcome and potential adverse effects of chronic immunosuppression remain uncertain, as for organ transplantation, CTA is already a potential solution for some highly selected patients carrying physical disabilities such as large facial defects and bilateral hand amputation.

Tissue Transplantation in Plastic Surgery

The functional and aesthetic outcome following application of conventional reconstructive procedures or prosthetic materials is not satisfactory, especially in patients who have severe deformities and disabilities. Since the first successful hand transplantation in France in 1998, composite tissue allograft transplantation has gained a great deal of interest in the field of plastic surgery. It is obvious that composite tissue allograft transplantation will improve patients' life quality, but this might be at the expense of decreasing life expectancy. Currently, the main obstacle for composite tissue allograft transplantation is the use of life-long immunosuppression therapy because of their well-known side effects. In addition, the ethical, social, and psychologic issues are raised when discussing face transplantation. The long-term results of the recently performed partial face transplantations will be critical to judge the future applications of partial or total face transplantation.

A New Rat Model of Maxilla Allotransplantation

We developed a rat model to test the effects of vascularized maxilla allotransplantation on composite maxillary substructures. Allograft maxilla transplantations were performed across the major histocompatibility barrier between 10 Lewis-Brown-Norway (RT1(n+l)) and 10 Lewis (RT1(l)) recipient rats under cyclosporin A monotherapy. Grafts were dissected along Le-Fort II osteotomy lines based on the common carotid artery and external jugular vein and transplanted to the anterior abdominal wall via microvascular anastomosis. Allografts were examined by tomography, flow cytometry, angiography, and histology. Three of the allografts survived up to 105 days without any signs of rejection. High level of donor-specific chimerism for T-cell and B-cell lineages was maintained in the peripheral blood. The incisors continued to grow; teeth buds, bone, cartilage, and mucosa remained intact. Moderate inflammation of the nasal, oral mucosa, and keratinous metaplasia was noted histologically. We created a maxilla allotransplantation model that allows the study of immunologic responses and demonstrates potential clinical applications based on the growth properties of the allograft.

Composite Hemiface/Calvaria Transplantation Model in Rats

BACKGROUND

Extensive craniomaxillofacial deformities including bone and soft-tissue defects are always challenging for reconstructive surgeons. The purpose of this study was to extend application of the face/scalp transplantation model in the rat by incorporation of the vascularized calvarial bone, based on the same vascular pedicle, as a new treatment option for extensive craniomaxillofacial deformities with large bone defects.

METHODS

Seven composite hemiface/calvaria transplantations were performed across major histocompatibility complex barrier between Lewis-Brown Norway and Lewis rats. Seven donor and seven recipient rats were used in this study. Hemicalvarial bone and face grafts were dissected on the same pedicle of the common carotid artery and jugular vein and were transplanted to the deepithelialized donor faces. All rats received tapered and continuous doses of cyclosporine A monotherapy. Evaluation methods included flap angiography, daily inspection, computed tomographic scan, and bone histology.

RESULTS

Flap angiography demonstrated the vascular supply of the bone. The average survival time was 154 days. There were no signs of rejection and there was no flap loss noted at 220 days posttransplantation. Bone histology at days 7, 30, 63, and 100 after transplantation revealed viable bone at all time points, and computed tomographic scans taken at days 14, 30, and 100 revealed normal bones without resorption.

CONCLUSIONS

For extensive face deformities involving large bone and soft-tissue defects, this new osteomusculocutaneous hemiface/calvaria flap model may serve to create new reconstructive options for covering during one surgical procedure.

Long-term survival of an allografted submandibular gland in a miniature swine model given immunosuppressant drugs

We used a model of allografts of submandibular glands in miniature swine to test the requirements of immunosuppressants for the survival of such grafts. Animals in the first group (n=6) were given no immunosuppressant, and the submandibular glands were rejected within 7 days. Those in the low-dose group (n=4) were treated with a low dose of cyclosporine, methylprednisolone, and azathioprine. The allografts were rejected on days 15, 17, 19, and 20. The animals in the high-dose group (n=6) were treated with a high dose of cyclosporin, methylprednisolone, and azathioprine. Three allografts were rejected, on days 35, 48, and 60. One animal died from anaesthetic problems on day 30 after transplantation, and there were no signs of rejection in the allograft. The other two allografts survived for 100 days with secretory function and no signs of rejection. After we discontinued the immunosuppression on day 100, the two remaining allografts were rejected on days 121 and 128. Blood tests and biopsy specimens of the heart, lung, liver, and kidneys were normal in all animals that were given immunosuppressants. To our knowledge, this study is the first to describe long-term survival of allografted submandibular glands with secretory function in miniature swine.

Reinnervation of laryngeal muscles: a study of changes in myosin heavy chain expression

Direct repair of the recurrent laryngeal nerve (RLN) results in synkinesis and compromised laryngeal function. We have therefore developed a pig model to investigate whether anastomosis of the phrenic nerve with the abductor branch of the RLN leads to specific reinnervation of abductor muscles. Expression of myosin heavy chain protein (MyHC), a marker of appropriate reinnervation, was determined in the posterior cricoarytenoid (PCA) abductor and thyroarytenoid (TA) adductor muscles following nerve injury and repair. The denervated PCA muscle exhibited decreased levels of the fast-type MyHC isoforms IIA and IIB, and increased slow-type MyHC expression. Similarly, there was a fall in type IIB levels in the denervated TA muscle but increases in both IIA and slow MyHC. Four months after repair, the MyHC expression in the PCA was near normal, suggesting that our model reduces the risk of synkinesis and ensures the accurate muscle reinnervation required for full functional recovery.

Strategies for Tolerance Induction in Nonhuman Primates

Recent advances in the field of reconstructive surgery and immunology resulted in increased interest in composite tissue allograft (CTA) transplantation. Up to date, more than 50 CTA transplants have been reported in humans. A significant number of experimental studies on CTA transplants under different protocols of tolerance-inducting strategies have been reported in small-animal models. There is however, a limited number of CTA transplants performed in nonhuman primates. To reach the ultimate clinical success in CTA transplantation, more experimental studies on tolerance induction in nonhuman primates are needed to apply these immunomodulatory protocols to CTA transplants in humans. In this review, strategies for tolerance induction in the nonhuman primate model in solid organ and CTA transplants are presented in 3 major categories: chimerism induction, T-cell depletion, and costimulatory receptor blockade.

Perspectives on Hand Transplantation

The early experience of hand transplantation has yielded a mixture of successes and failures. No life-threatening adverse effects have been encountered from immunosuppression, yet additional medications were required in some cases with unknown long-term efficacy or side effects. Limited functional returns have been observed, but any effect of chronic rejection is too early to determine. Although the experience has confirmed the benefits of hand transplantation to patients and their families, the future of hand transplantation on a wide scale is dependent on further research to alter its risk-benefit balance.

New Surgical Approach in Facial Transplantation Extends Survival of Allograft Recipients

We have previously developed a composite total face-scalp allotransplantation model based on bilateral common carotid arteries (CCA) and external jugular veins. To decrease the mortality rates, different modifications of arterial anastomoses in the facial allograft recipients are presented. Eighteen full face-scalp allograft transplantations were performed across major histocompatibility (MHC) barriers between ACI (RT1) donors and Lewis (RT1) recipients. Bilateral CCA and bilateral external carotid arteries of the recipients were used as recipient vessels to vascularize the flap in 5 and 4 transplants, respectively. In 9 transplants, unilateral CCA of the recipients were used to vascularize the face/scalp flap. All the animals received CsA 16 mg/kg/d Sc, which was tapered over 4 weeks to 2 mg/kg/d. In transplants utilizing bilateral CCA, the survival rate of the animals was very short. Transplants in which unilateral CCA were used yielded 100% survivals over 200 days posttransplant. These modifications of arterial anastomoses have significantly improved survival of facial allograft recipients.

Development and Maintenance of Donor-Specific Chimerism in Semi-Allogenic and Fully Major Histocompatibility Complex Mismatched Facial Allograft Transplants

BACKGROUND

The clinical application of composite tissue allograft transplants opened the discussion on the restoration of facial deformities by allotransplantation. We introduce a hemifacial allograft transplant model to investigate the rationale for the development of operational tolerance across a major histocompatibility complex (MHC) barrier.

MATERIAL AND METHODS

Thirty rats were studied in five groups of six animals each. The composite hemiface isograft transplantations were performed in group 1. Allograft rejection controls included semi-allogenic transplantations from LBN (RT1(1+n) donors (group 2) and fully allogenic transplantations from ACI (RT1a) donors (group 3) to LEW (RT1(1)) recipients. In the allograft treatment groups, recipients of LBN (group 4) and ACI donors (group 5) were treated with cyclosporine A monotherapy (16 mg/kg/day, tapered to 2 mg/kg/day). Face allografts were evaluated clinically and histologically. Donor-specific chimerism for MHC class I RT1n and RT1a antigens was assessed by flow cytometry. Mixed lymphocyte reaction for donor-specific tolerance in vitro was tested at day 160 posttransplant.

RESULTS

Isograft controls survived indefinitely. All nontreated allografts rejected within 5 to 8 days posttransplant. Long-term survival was achieved in 100% of LBN (up to 400 days) and ACI (up to 330 days) recipients. At day 160, posttransplant donor-specific chimerism was present in recipients of LBN (10.14% CD4/RT1n, 6.38% CD8/RT1n, 10.02% CD45RA/RT1n) and ACI (17.54% CD4/RT1a, 9.28% CD8/RT1a) transplants, and mixed lymphocyte reaction confirmed tolerance in recipients of LBN transplants and moderate reactivity in recipients of ACI allografts.

CONCLUSION

Operational tolerance was induced in hemiface allograft transplants across an MHC barrier under cyclosporine A monotherapy protocol. It was associated directly with the presence of multilineage donor-specific chimerism.

Tolerance Induction in Composite Facial Allograft Transplantation in the Rat Model

Clinical application of composite tissue allograft transplants opened discussion on the restoration of facial deformities by allotransplantation. The authors introduce a hemifacial allograft transplant model to investigate the rationale for the development of functional tolerance across the major histocompatibility complex barrier. Eighteen rats in three groups were studied. The composite hemifacial allotransplantations including the ear and scalp were performed between Lewis-Brown Norway (RT1l+n) and Lewis (RT1l) rats and isotransplantations were performed between Lewis rats. Isograft controls (n = 6) and allograft controls (n = 6) did not receive treatment. Allografts in treatment group (n = 6) were treated with cyclosporine A 16 mg/kg/day during the first week; this dose was tapered to 2 mg/kg/day over 4 weeks and maintained at this level thereafter. Functional tolerance to face allografts was evaluated clinically and histologically. Donor-specific chimerism was assessed at days 21 and 63 by flow cytometry. In vitro evaluation of donor-specific tolerance was performed by mixed lymphocyte reaction at day 160 after transplantation. Isograft controls survived indefinitely. All nontreated allografts were rejected within 5 to 7 days after transplantation, as confirmed by histopathologic analysis. Five of six face allografts under the cyclosporine A protocol showed no signs of rejection for up to 240 days and remained alive and under evaluation, whereas one animal showed signs of rejection at day 140. This was reversed by adjustment of the cyclosporine A dose. At day 21 after transplantation, flow cytometric analysis of the donor-specific chimerism showed 1.11 percent of double-positive CD4FITC/RT1Ac-Cy7 and 1.43 percent of double-positive CD8PE/RT1Ac-Cy7 T-cell populations in the peripheral blood of hemiface allotransplant recipients. The chimerism level of double-positive CD4FITC/RT1Ac-Cy7 T cells increased to 3.39 percent, whereas it remained stable for the double-positive CD8PE/RT1Ac-Cy7 T-cell population at day 63 after transplantation (1.00 percent). The mixed lymphocyte reaction assay at day 160 after transplantation revealed donor-specific tolerance to donor (Lewis-Brown Norway) antigens and strong reactivity to the third-party (ACI) alloantigens. In this study, donor-specific chimerism and functional tolerance were induced in hemifacial allograft transplants across the major histocompatibility complex barrier under cyclosporine A monotherapy protocol. This model will allow further studies on tolerance induction protocols.

Composite tissue allotransplantation and reconstructive surgery: first clinical applications

OBJECTIVE

To review the first clinical cases of composite tissue allotransplantation (CTA) for reconstructive surgery and to discuss the outcome of and indications for these procedures in the context of chronic immunosuppression.

SUMMARY BACKGROUND DATA

The first human hand transplant was performed in 1998. This procedure, as well as other composite tissue transplants, offers the potential for correcting untreatable large tissue defects. However, concerns remain regarding obligatory chronic immunosuppression and long-term functional results.

METHODS

All the CTAs performed in humans that have been published or documented were reviewed. The preexisting clinical conditions and surgical procedures and the immunosuppressive therapy are described. The functional results and the complications or side effects of the treatment are detailed.

RESULTS

Vascularized tendons (two cases), vascularized femoral diaphyses (three cases), knees (five cases), hands (four bilateral and seven unilateral cases), larynx (one case), and nonvascularized peripheral nerves (seven cases) have been transplanted in humans in the past decade. Rejection was prevented in most cases without difficulty. Early results are encouraging, particularly for hand and larynx transplants, but will need to be evaluated in the long term and in a larger number of patients.

CONCLUSIONS

CTA holds great potential for reconstructive surgery but is at present restricted by the risks of chronic immunosuppression and uncertain long-term results.