How Reconstructive Transplantation Is Different From Organ Transplantation—and How It Is Not

Vascularized composite allotransplantation: emerging psychosocial issues in hand, face, and uterine transplant

PURPOSE OF REVIEW

Currently, several research approaches warrant further attention, given the influence of psychosocial and bioethical issues on the success of upper extremity (UETx), face (FTx), and uterine transplantation (UTx). This review will highlight recent results of psychosocial and bioethical research in the field of vascularized composite allotransplantation (VCA), discuss most recent findings, provide information to guide future research approaches, and address the importance of a multicenter research approach to develop international standards.

RECENT FINDINGS

Previously published reports have tried to identify psychosocial factors that are essential to predict psychosocial outcomes and guide posttransplant treatment after VCA procedures. These issues in VCA are receiving more attention but we are still at the beginning of a systematic investigation of these domains. This review article summarizes the emerging psychosocial issues in UeTx, FTx, and UTx by including recent literature and current clinical practice.

SUMMARY

Even though different VCA procedures address different domains leading to specific psychosocial issues, common aspects impacting all forms of VCA would benefit of further coordination. These domains include clinical resources, public attitude and perception, bioethical considerations, adherence and rehabilitation, motives for VCA, information needs and multidisciplinary communication, body image, domains of quality of life, coping strategies, and follow-up care.

Hand Transplantation-Risks and Benefits

Composite tissue allotransplantation (CTA) is the culmination of progress in transplantation, allowing the reconstruction of the hand in amputees. Worldwide, more than 100 procedures have been performed. The aim of this work was to understand the hand allotransplantation approach, making known current aspects, risks, and benefits. A PubMed research was realized between October 2018 and March 2019, including terms like "Hand transplantation" AND "Composite tissue allotransplantation," "Hand transplantation" AND "Functional outcomes," "Hand transplantation" AND "Immunosuppression," "Hand prosthetics," "Hand Transplantation" AND "Ethics." There were included papers between 1995 and 2018, with English language, amputee human adults, systematic reviews, and clinical studies. Seventy-two papers were fully evaluated. There are technical aspects that influence the procedure like team coordination or surgical technique. It requires a long-life treatment, which has risks such as toxicity or infections. However, it allows the recovery of fine movements, and independence, to perform detailed tasks. The indications must be carefully considered, because some patients benefit from the use of prosthesis. CTA has become an option for amputees so it is important to do more research, to determine the benefits of this procedure. It is not considered a life-saving procedure, so there is an ethical debate because of the risks.

A Flow Dynamic Rationale for Accelerated Vascularized Composite Allotransplant Rejection

BACKGROUND

From 1996 to 2000, Diefenbeck et al. carried out six knee vascularized composite allotransplants. The allotransplants were composed of bone, soft tissue, and femoral vascular pedicle (25 to 40 cm). All rejected between 14 and 56 months. Failures were attributed to chronic rejection. In 2008, the Louisville team lost their fourth patient's hand transplant at 8 months. During the rejection workup, intraoperative findings noted a thickened arterial pedicle attributed to intimal hyperplasia with significant fibrotic perivascular tissue and a near "no-flow phenomenon." No cutaneous rejection was appreciated and failure was attributed to chronic rejection.

METHODS

Data were collected from two teams, one in Germany and the other in Louisville, Kentucky. The population under study consisted of the six knee and one hand transplants. The factor of interest was the long donor arterial pedicle. The outcome measurements were transplant survival time and histopathologic results.

RESULTS

There are only seven published vascularized composite allotransplant cases where a donor artery longer than 25 cm was used. This cohort represents a 100 percent accelerated failure rate. The cause of these losses remains unexplained. The donor arteries suffered from T-cell-mediated rejection and ischemia-induced media/adventitial necrosis.

CONCLUSIONS

We hypothesize that the donor artery rejected at an accelerated rate because of ischemia caused by disruption of the external vasa vasorum in conjunction with intimal hyperplasia induced by T-cell-mediated rejection that led to disruption of the Windkessel effect. Loss of this effect presented as intimal hyperplasia accelerated by ischemia causing an expedited transplant failure.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Inducción de tolerancia inmunológica: alotrasplantes compuestos vascularizados y trasplantes de órgano sólido

Introducción. La inducción de tolerancia inmunológica solucionaría los problemas asociados con la inmunosupresión de por vida, necesaria para evitar el rechazo de aloinjertos.Objetivos. Revisar aspectos inmunológicos, modelos clínicos utilizados y resultados obtenidos en la tolerancia y comparar los resultados obtenidos con trasplante de órgano sólido y alotrasplante compuesto vascularizado.Materiales y métodos. Se realizó una búsqueda en la base de datos PubMed que arrojó 299 resultados; se revisaron las bibliografías de los artículos y se consultaron las referencias pertinentes. Al final se seleccionaron 83 artículos.Resultados. Existen mecanismos centrales y periféricos para mantener la tolerancia a antígenos propios; en la práctica clínica, la tolerancia central ha sido más utilizada, esto se ha hecho mediante estrategias que utilizan trasplante conjunto de medula ósea. Varios ensayos clínicos, la mayoría en pacientes con trasplante renal, han mostrado resultados prometedores pero inconsistentes.Conclusiones. En trasplantes renales fue posible suspender de forma exitosa la inmunosupresión, mientras que en trasplantes de mano se logró disminuirla considerablemente. El quimerismo inmunológico parece ser indispensable para el desarrollo de tolerancia a aloinjertos, por lo que es necesario desarrollar protocolos para inducir quimerismo mixto persistente.

An integrated view of immune monitoring in vascularized composite allotransplantation

PURPOSE OF REVIEW

Vascularized composite allotransplantation (VCA) has several immunological peculiarities that imply a specific immune monitoring. Here, we provide an integrated view of current procedures of immune monitoring in VCA and potential complementary approaches learned from organ transplantation.

RECENT FINDINGS

Because the skin is highly immunogenic and is the main target of the alloimmune response, immune monitoring in VCA essentially relies on visual inspection and pathological examination of for-causes and protocol skin biopsies. Light microscopical and immunohistochemical analyses enable us to identify skin lesions that are characteristic, but not specific, of allograft rejection. Complementary approaches of immunological assessment may assist in reinforcing the diagnosis of rejection and preventing over-immunosuppression or under-immunosuppression. Such approaches can inform either on the patient's global immune status or more specifically on the B-cell-mediated or T-cell-mediated immune responses against donor antigens.

SUMMARY

Strategies that integrate both the current 'gold standards' of monitoring in VCA and a complementary multilayer immunological assessment are likely to provide the highest precision for the personalized determination of the recipients' immunological status. The objective is a tailored adaptation of immunosuppressive treatment.

Head Transplantation in Mouse Model

AIMS

The mouse model of allo-head and body reconstruction (AHBR) has recently been established to further the clinical development of this strategy for patients who are suffering from mortal bodily trauma or disease, yet whose mind remains healthy. Animal model studies are indispensable for developing such novel surgical practices. The goal of this work was to establish head transplant mouse model, then the next step through the feasible biological model to investigate immune rejection and brain function in next step, thereby promoting the goal of translation of AHBR to the clinic in the future.

METHODS AND RESULTS

Our approach involves retaining adequate blood perfusion in the transplanted head throughout the surgical procedure by establishing donor-to-recipient cross-circulation by cannulating and anastomosing the carotid artery on one side of the body and the jugular vein on the other side. Neurological function was preserved by this strategy as indicated by electroencephalogram and intact cranial nerve reflexes.

CONCLUSIONS

The results of this study support the feasibility of this method for avoiding brain ischemia during transplantation, thereby allowing for the possibility of long-term studies of head transplantation.

Hand transplants and the mandate for tolerance

PURPOSE OF REVIEW

The field of vascularized composite allograft (VCA) to achieve its full potential will require induction of tolerance. This review will introduce a new method of potential inducing tolerance in hand transplantation.

RECENT FINDINGS

Hand transplantation is never a life-extending transplant. This fact resulted in considerable debate both for and against the use of immunosuppression for nonlife-extending transplants. There is considerable debate about the ethics of hand transplantation. There is now consensus that nonlife-extending transplants are acceptable in properly selected patients. However, ideally, hand transplants should not receive life-long immunosuppression. Therefore, attempts to achieve drug-free tolerance through nonlife-endangering therapies are warranted. To this end, we propose implementation of tolerizing therapy long after periinflammation has subsided and drug minimization has proven successful. Evidence that short-term treatment with low doses of IL-2 or a long-lived IL-2 immunoglobulin (Ig) can tilt the balance of immunity from tissue destructive to tolerance come from preclinical demonstrations in mouse and nonhuman primate models of autoimmunity and/or transplantation and even more recent clinical trials.

SUMMARY

We believe that with the proper use of low-dose IL-2 given at an opportune time in the inflammatory process of transplant that reduce immunosuppression and even tolerance can be induced in hand transplantation. We propose that tolerance can be inducted after a long period of conventional treatment to avoid 'tolerance-hindering' adverse inflammation that occurs in the posttransplant period. With abatement of posttransplant inflammation and with time, we will institute low-dose IL-2-based therapy to support the proliferation, viability and functional phenotype of regulatory T cells.

Allogeneic head and body reconstruction: mouse model

AIMS

There is still no effective way to save a surviving healthy mind when there is critical organ failure in the body. The next frontier in CTA is allo-head and body reconstruction (AHBR), and just as animal models were key in the development of CTA, they will be crucial in establishing the procedures of AHBR for clinical translation.

METHODS AND RESULTS

Our approach, pioneered in mice, involves retaining the donor brain stem and transplanting the recipient head. Our preliminary data in mice support that this allows for retention of breathing and circulatory function. Critical aspects of the current protocol include avoiding cerebral ischemia through cross-circulation (donor to recipient) and retaining the donor brain stem. Successful clinical translation of AHBR will become a milestone of medical history and potentially could save millions of people.

CONCLUSIONS

This experimental study has confirmed a method to avoid cerebral ischemia during the surgery and solved an important part of the problem of how to accomplish long-term survival after transplantation and preservation of the donor brain stem.

Psychological aspects of hand transplantation

PURPOSE OF REVIEW

Psychosocial aspects are important indicators for reconstructive hand transplantation (RHT). They warrant further research attention given the influence of psychosocial factors on the success of RHT. This review will contrast RHT with solid organ transplantation, provide information to guide selection of RHT candidates and ethical implications, share information on psychological outcomes, and address the importance of a multicenter research approach.

RECENT FINDINGS

Previously published RHT reports have tried to identify psychosocial factors that are essential to guide selection of RHT candidates and that predict psychosocial outcomes. These issues in RHT are receiving increased attention, but standardized psychosocial evaluation and follow-up protocols are still needed. Recent study highlights the potential for a multicenter research approach that uses standardized assessment strategies and also emphasizes the need for a shared assessment approach to understand psychosocial outcomes.

SUMMARY

RHT combines the technical rigors of hand surgery and microsurgery with the complex multidisciplinary care that defines modern transplantation medicine. As recent work has provided a more complete picture of the complexities of the psychosocial factors in RHT, a psychosocial assessment protocol developed with input across the centers currently performing this procedure would capitalize on the collective diverse clinical experiences and standardize the assessment and follow-up protocol. With such standardized procedures in place, psychosocial risk factors for both poor psychosocial and medical/surgical outcomes can be identified which can inform the selection or preparation of future candidates.

An overview of psychosocial assessment procedures in reconstructive hand transplantation

There have been more than 90 hand and upper extremity transplants performed worldwide. Functional and sensory outcomes have been reported in several studies, but little is known about the psychosocial outcomes. A comprehensive systematic literature review was performed, addressing the psychosocial impact of reconstructive hand transplantation. This review provides an overview of psychosocial evaluation protocols and identifies standards in this novel and exciting field. Essentials of the psychosocial assessment are discussed and a new protocol, the 'Chauvet Protocol', representing a standardized assessment protocol for future multicenter psychosocial trials is being introduced.

Composite tissue allotransplantation and dysregulation in tissue repair and regeneration: a role for mesenchymal stem cells

Vascularized composite tissue allotransplantation is a rapidly evolving area that has brought technological advances to the forefront of plastic surgery, hand surgery, and transplant biology. Composite tissue allografts (CTAs) may have profound functional, esthetic, and psychological benefits, but carry with them the risks of life-long immunosuppression and the inadequate abilities to monitor and prevent rejection. Allografts may suffer from additional insults further weakening their overall benefits. Changes in local blood flow, lack of fully restored neurologic function, infection, inflammation with subsequent dysregulated regenerative activity, and paucity of appropriate growth factors may all be involved in reducing the potential of CTAs and therefore serve as new therapeutic targets to improve outcomes. Strategies involving minimized immunosuppression and pro-regenerative therapy may provide a greater path to optimizing long-term CTA function. One such strategy may include mesenchymal stem cells (MSCs), which can provide unique anti-inflammatory and pro-regenerative effects. Insights gained from new studies with MSCs on composite allografts, advances in tissue regeneration reported in other MSC-based clinical studies, as well as consideration of newly described capacities of MSCs, may provide new regenerative based strategies for the care of CTAs.

The need for inducing tolerance in vascularized composite allotransplantation

Successful hand and face transplantation in the last decade has firmly established the field of vascularized composite allotransplantation (VCA). The experience in VCA has thus far been very similar to solid organ transplantation in terms of the morbidity associated with long-term immunosuppression. The unique immunological features of VCA such as split tolerance and resistance to chronic rejection are being investigated. Simultaneously there has been laboratory work studying tolerogenic protocols in animal VCA models. In order to optimize VCA outcomes, translational studies are needed to develop less toxic immunosuppression and possibly achieve donor-specific tolerance. This article reviews the immunology, animal models, mixed chimerism & tolerance induction in VCA and the direction of future research to enable better understanding and wider application of VCA.

Mechanisms and mediators of inflammation: potential models for skin rejection and targeted therapy in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is an effective treatment option for patients suffering from limb loss or severe disfigurement. However, postoperative courses of VCA recipients have been complicated by skin rejection, and long-term immunosuppression remains a necessity for allograft survival. To widen the scope of this quality-of-life improving procedure minimization of immunosuppression in order to limit risks and side effects is needed. In some aspects, the molecular mechanisms and dynamics of skin allograft rejection seem similar to inflammatory skin conditions. T cells are key players in skin rejection and are recruited to the skin via activation of adhesion molecules, cytokines, and chemokines. Blocking these molecules has not only shown success in the treatment of inflammatory dermatoses, but also prolonged graft survival in various models of solid organ transplantation. In addition to T cell recruitment, ectopic lymphoid structures within the allograft associated with chronic rejection in solid organ transplantation might contribute to the strong alloimmune response towards the skin. Selectively targeting the molecules involved offers exciting novel therapeutic options in the prevention and treatment of skin rejection after VCA.