Vascularized composite allotransplantation - a Council of Europe position paper

The Global Experience of Laryngeal Transplantation: Series of Eleven Patients in Three Continents

BACKGROUND

The loss of laryngeal function affects breathing, swallowing, and voice, thus severely compromises quality of life. Laryngeal transplantation has long been suggested as a solution for selected highly affected patients with complete laryngeal function loss.

OBJECTIVE

To obtain insights regarding the advantages, weaknesses, and limitations of this procedure and facilitate future advances, we collected uniform data from all known laryngeal transplants reported internationally.

METHODOLOGY

A case series. Patients were enrolled retrospectively by each institutional hospital or clinic. Eleven patients with complete loss of laryngeal function undergoing total laryngeal transplantation between 1998 and 2018 were recruited.

RESULTS

After a minimum of 24 months follow-up, three patients had died (27%), and there were two graft explants in survivors, one total and one partial, due to chronic rejection. In the remaining cases, voice was functional in 62.5% and 50% achieved decannulation. Swallowing was initially restricted, but only one patient was gastrostomy-dependent by 6 months and all had normal or near-normal swallowing by the end of year two after transplantation. Median follow-up was 73 months. Functional (voice, swallowing, airway) recovery peaked between 12 and 24 months.

CONCLUSIONS

Laryngeal transplantation is a complex procedure with significant morbidity. Significant improvements in quality of life are possible for highly selected individuals with end-stage laryngeal disorders, including laryngeal neoplasia, but further technical and pharmacological developments are required if the technique is to be more widely applicable. An international registry should be created to provide better quality pooled data for analysis of outcomes of any future laryngeal transplants.

LEVEL OF EVIDENCE

IV Laryngoscope, 2024.

The contribution of the donor vascularised hand and face allograft in transplant rejection: An immunological perspective

Overcoming immunological rejection remains a barrier to the safe adoption of Vascularised Composite Allotransplantation (VCA). To mitigate this risk, clinical protocols have been derived from solid organ transplantation, targeting recipient immunomodulation, yet VCA is unique. Face and hand composite allografts are composed of multiple different tissues, each with their own immunological properties. Experimental work suggests that allografts carry variable numbers and populations of donor leukocytes in an organ specific manner. Ordinarily, these passenger leukocytes are transferred from the donor graft into the recipient circulation after transplantation. Whether alloantigen presentation manifests as acute allograft rejection or transplant tolerance is unknown. This review aims to characterise the immunological properties of the constituent parts of the donor face and hand, the potential fate of donor leukocytes and to consider theoretical graft specific interventions to mitigate early rejection.

Emerging strategies for tissue engineering in vascularized composite allotransplantation: A review

Vascularized composite allotransplantation (VCA), which can effectively improve quality of life, is a promising therapy for repair and reconstruction after face or body trauma. However, intractable issues are associated with VCA, such as the inevitable multiple immunogenicities of different tissues that cause severe rejection, the limited protocols available for clinical application, and the shortage of donor sources. The existing regimens used to extend the survival of patients receiving VCAs and suppress rejection are generally the lifelong application of immunosuppressive drugs, which have side effects. Consequently, studies aiming at tissue engineering methods for VCA have become a topic. In this review, we summarize the emerging therapeutic strategies for tissue engineering aimed to prolong the survival time of VCA grafts, delay the rejection and promote prevascularization and tissue regeneration to provide new ideas for future research on VCA treatment.

What is needed to ensure long-term sustainability for the field of vascularized composite allotransplantation?

The field of vascularized composite allotransplantation (VCA) has demonstrated remarkable advances since its inception with some excellent long-term results in a variety of graft types. However, unlike solid organ transplantation, it has yet to become mainstream. We therefore discuss strategies on ensuring long-term sustainability by addressing continued clinical developments of VCA to improve the risk-to-benefit balance, importance of public support, improved policy and financial support, and need for a bridge to the future of transplant surgery. There has been headway on all fronts and collaboration among the VCA centers for centralization of data and incorporation of patient voices will be essential for continued progress.

Defining chronic rejection in vascularized composite allografts - do we have reliable surrogates to look for?

PURPOSE OF REVIEW

Chronic rejection (CR) is a major threat in the field of vascularized composite tissue allografts (VCAs) as it causes graft dysfunction and usually graft loss. Unfortunately, knowledge of CR in VCA is incomplete because of the limited number of VCA recipients, the heterogeneous nature of VCAs and the short follow-up.

RECENT FINDINGS

The diagnosis of CR in VCA has relied on clinical and pathological findings. Clinical changes include graft fibrosis, dyschromia and ischemic/necrotic ulcerations. Pathological changes primarily affect allograft vessels and manifest with graft vasculopathy (i.e. myo-intimal proliferation and luminal narrowing of allograft vessels, leading to graft ischemia). Attempts are made to diagnose CR with non- or minimally-invasive techniques, such as imaging studies (ultrasound biomicroscopy, functional magnetic resonance imaging) and serum biomarkers. These techniques provide interesting results and further insight into the mechanisms of CR in VCA.

SUMMARY

The diagnosis of CR in VCA still relies mainly on clinicopathological graft alterations; unfortunately, these become overt rather late during the rejection process, when reversal of CR is problematic. More recent, minimally- or non-invasive techniques have provided encouraging results, but their usefulness in the diagnosis of CR requires further studies. These data highlight the paramount importance of CR prevention.

Tolerance Induction in Vascularized Composite Allotransplantation-A Brief Review of Preclinical Models

Pre-clinical studies are an obligatory tool to develop and translate novel therapeutic strategies into clinical practice. Acute and chronic rejection mediated by the recipient's immune system remains an important limiting factor for the (long-term) survival of vascularized composite allografts (VCA). Furthermore, high intensity immunosuppressive (IS) protocols are needed to mitigate the immediate and long-term effects of rejection. These IS regiments can have significant side-effects such as predisposing transplant recipients to infections, organ dysfunction and malignancies. To overcome these problems, tolerance induction has been proposed as one strategy to reduce the intensity of IS protocols and to thereby mitigate long-term effects of allograft rejection. In this review article, we provide an overview about animal models and strategies that have been used to induce tolerance. The induction of donor-specific tolerance was achieved in preclinical animal models and clinical translation may help improve short and long-term outcomes in VCAs in the future.

Using team science in vascularized composite allotransplantation to improve team and patient outcomes

Reconstructive allografts using Vascularized Composite Allotransplantation (VCA) are providing individuals living with upper limb loss and facial disfigurement with new opportunities for a sensate, esthetically acceptable, and functional alternative to current treatment strategies. Important research attention is being paid to how best to assess and screen candidates for VCA, measure optimal patient outcomes, and support patient adherence to lifelong behaviors and medical regimens. Far less attention, however, has been dedicated to the team science required for these complex VCA teams to form, prepare, and provide the highest quality clinical and psychosocial care to those receiving VCA. VCA teams are unique in that they require specialized team members whose scope of practice may not otherwise overlap. The team also needs to constantly negotiate balancing patient safety with multiple risks throughout the transplant process. This study aimed to elucidate the team science needed for this highly innovative and complex area of medicine. Using in-depth qualitative interviews with 14 VCA team members and observations at team meetings, we found that careful consideration of team composition, team structure, and organizational commitment (e.g., local culture and team values; investment of resources) influences team performance and patient outcomes, but that to be efficient and truly effective, teams need to commit to developing processes that foster collaboration. These processes are action-oriented (e.g., communication, leadership), strategic (e.g., planning, training) and interpersonal (e.g., conflict management, trust building). Dedication and commitment to team science allows teams to manage conflict under stress and exercise ways to leverage strengths to provide optimal performance or patient psychosocial and clinical outcomes. This study can provide insight into quality improvement efforts for VCA teams and guidance for other transplant programs that wish to consider expansion into VCA.

Bionic Prostheses: The Emerging Alternative to Vascularised Composite Allotransplantation of the Limb

Twenty years have surpassed since the first vascularised composite allotransplantation (VCA) of the upper limb. This is an opportunity to reflect on the position of VCA as the gold standard in limb reconstruction. The paucity of recipients, tentative clinical outcomes, and insufficient scientific progress question whether VCA will remain a viable treatment option for the growing numbers of amputees. Bionic technology is advancing at a rapid pace. The prospect of widely available, affordable, safely applied prostheses with long-standing functional benefit is appealing. Progress in the field stems from the contributions made by engineering, electronic, computing and material science research groups. This review will address the ongoing reservations surrounding VCA whilst acknowledging the future impact of bionic technology as a realistic alternative for limb reconstruction.

A systematic review of immunomodulatory strategies used in skin-containing preclinical vascularized composite allotransplant models

BACKGROUND

Acute rejection remains a vexing problem in vascularized composite allotransplantation (VCA). Available immunosuppressive regimens are successful at minimizing alloimmune response and allowing VCA in humans. However, repeated rejection episodes are common, and systemic side effects of the current standard regimen (Tacrolimus, MMF, Prednisone) are dose limiting. Novel immunomodulatory approaches to improve allograft acceptance and minimize systemic toxicity are continuously explored in preclinical models. We aimed to systematically summarize past and current approaches to help guide future research in this complex field.

METHODS

We conducted a systematic review of manuscripts listed in the MEDLINE and PubMed databases. For inclusion, articles had to primarily investigate the effect of a therapeutic approach on prolonging the survival of a skin-containing preclinical VCA model. Non-VCA studies, human trials, anatomical and feasibility studies, and articles written in a language other than English were excluded. We followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

RESULTS

The search retrieved 980 articles of which 112 articles were ultimately included. The majority of investigations used a rat model. An orthotopic hind limb VCA model was used in 53% of the studies. Cell and drug-based approaches were investigated 58 and 52 times, respectively. We provide a comprehensive review of immunomodulatory strategies used in VCA preclinical research over a timeframe of 44 years.

CONCLUSION

We identify a transition from anatomically non-specific to anatomical models mimicking clinical needs. As limb transplants have been most frequently performed, preclinical research focused on using the hind limb model. We also identify a transition from drug-based suppression therapies to cell-based immunomodulation strategies.

Genetic modification of limbs using ex vivo machine perfusion

Genetic engineering is a promising tool to repair genetic disorders, improve graft function or to reduce immune responses towards the allografts. Ex vivo organ perfusion systems have the potential to mitigate ischemic-reperfusion injury, prolong preservation time or even rescue organ function. We aim to combine both technologies to develop a modular platform allowing the genetic modification of vascularized composite (VC) allografts. Rat hind limbs were perfused ex vivo under subnormothermic conditions with lentiviral vectors. Specific perfusion conditions such as controlled pressure, temperature and flow rates were optimized to support the genetic modification of the limbs. Genetic modification was detected in vascular, muscular and dermal limb tissues. Remarkably, skin follicular and interfollicular keratinocytes as well as endothelial cells (ECs) showed stable transgene expression. Furthermore, levels of injury markers such as lactate, myoglobin and lactate dehydrogenase (LDH) as well as histological analyses showed that ex vivo limb perfusion with lentiviral vectors did not cause tissue damage and limb cytokine secretion signatures were not significantly affected. The use of ex vivo VC perfusion in combination with lentiviral vectors allows an efficient and stable genetic modification of limbs representing a robust platform to genetically engineer limbs towards increasing graft survival after transplantation.

Donor-recipient matching in hand transplantation: a comparison of anthropometric measurements, 3-dimensional virtual models and printed epitheses

Donor-recipient matching in hand transplantation remains challenging. The usefulness of three-dimensional (3-D) virtual models and printed epitheses were compared with measurements on cadaveric extremities to evaluate the most accurate method of donor-recipient matching for allograft procurement. Ten anthropometric measurements were recorded from 12 human cadaveric upper extremities and matched to printed epitheses and 3-D virtual models. Five circumferential and two longitudinal measurements obtained an intra-class correlation of >0.75 with all three methods, with the Kaplan (0.973) and wrist circumferences (0.942) achieving the highest concordance. Measurement on cadaveric specimens was the most reliable method. Using different combinations of donor hand and recipient forearms, a series of 72 virtual transplantations were then created, and their compatibility rated by ten transplant surgeons. The results confirmed that anthropometric measurements, obtained directly from potential human donor limbs and based on wrist circumference as the primary parameter, provide the best and most clinically relevant donor-recipient match.

Facial Transplantation

Facial transplantation represents a unique surgical solution for challenging facial injury patterns in which conservative reconstructive techniques fail to provide a satisfactory functional and aesthetic result. With advances in the field of vascularized composite allotransplantation over the past 15 years, more than 40 of these procedures have been performed worldwide with two recent reports of facial re-transplantation. In this article we discuss the multidisciplinary approach that is required for successful transplantation as well as the surgical techniques used and postoperative management. With ongoing research, recent technological innovation, and increased efforts to promote greater generalizability and transparency in this field, patients with these complex injuries will continue to see improvements in their treatment options, and thus quality of life.

Process of Obtaining Social Consensus and 3-Year Functional Outcomes of the First Hand Allotransplantation in Korea

BACKGROUND

On February 2, 2017, the surgical team of ten board-certified hand specialists of W Hospital in Korea successfully performed the nation's first hand transplantation at Yeungnam University Medical Center (YUMC). This paper reports on the legal, financial, and cultural hurdles that were overcome to open the way for hand transplantation and its functional outcomes at 36 months after the operation.

METHODS

W Hospital formed a memorandum of understanding with Daegu city and YUMC to comply with government regulations regarding hand transplantation. Campaigns were initiated in the media to increase public awareness and understanding. With the city's financial and legal support and the university's medical cooperation, a surgical team performed a left distal forearm hand transplantation from a brain-dead 48-year-old man to a 35-year-old left-handed man.

RESULTS

With this successful allotransplantation, the Korean Act on Organ Transplantation has now been amended to include hand transplantation. Korean national health insurance has also begun covering hand transplantation. Functional outcome at 36 months after the operation showed satisfactory progress in both motor and sensory functions. The disabilities of the arm, shoulder, and hand score were 23. The final Hand Transplantation Score was 90 points. Functional brain magnetic resonance imaging shows significant cortical reorganization of the corticospinal tract, and reinnervation of intrinsic muscle is observed.

CONCLUSIONS

Hand transplantation at the distal forearm shows very satisfactory outcomes in functional, aesthetical, and psychological aspects. Legal and financial barriers against hand transplantation have long been the most burdensome issues. Despite this momentous success, there have been no other clinical applications of vascularized composite allotransplantation due to the limited acceptance by Korean doctors and people. Further public education campaigns for vascularized composite allotransplantation are needed to increase awareness and acceptance.

Limitations and limits and of vascularized composite allotransplantations: can we reach the holy grail?

PURPOSE OF REVIEW

In recent times, vascularized composite allotransplantation (VCA) have been gaining more attention and applications. Currently, VCA are at the highest level of the reconstruction pyramid, and thus the effects expected after them are intended to outweigh what the 'classical' reconstructive surgery can offer us, including even the most advanced microsurgical techniques.

RECENT FINDINGS

Over 40 patients have received a partial or full-face transplant. Others have received penis, uterus, larynx, abdominal wall, and lower extremity transplants. Each type of VCA has its own problems and limitations. However, resolving the limits defined by immunosuppression and improved donor selection would revolutionize all of them.

SUMMARY

Defining the limits and limitations of given procedures will not only allow for better preparation of transplant teams but will also help in determining the direction of future research.

Local immunosuppression in vascularized composite allotransplantation (VCA): A systematic review

BACKGROUND

Local immunosuppression in vascularized composite allotransplantation (VCA) aims to minimize immunosuppressant-related toxic and malignant side effects. Promising allograft survival data have been published by multiple workgroups. In this systematic review, we examine preclinical animal studies that investigated local immunosuppression in VCA.

MATERIAL AND METHODS

We conducted a systematic review of manuscripts listed in the MEDLINE and PubMed database concerning preclinical VCA models. Papers included had to be available as full-text and written in English. Non-VCA studies, human trials, and studies using cell-based therapy strategies were excluded. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Literature research retrieved 980 articles. Ten studies published between 2010 and 2019 met the inclusion and exclusion criteria. Seven out of ten articles demonstrated a significant prolongation of allograft survival by using local immunosuppression. Five articles employed tacrolimus (TAC) as the main immunosuppressive agent. Seven studies performed hind-limb VCA in a rat model.

CONCLUSION

The easily accessible location of skin containing VCAs makes it an ideal candidate for local immunosuppression. Published preclinical data are very promising in terms of improved allograft survival and reduced systemic toxicity.

Graft vasculopathy in upper extremity allotransplantation: Results of a retrospective high-resolution ultrasonographic study

Graft vasculopathy (GV) is the most severe pathologic change of chronic rejection in vascularized composite allotransplantation. Since 2012, the intimal media thickness (IMT) of radial and ulnar arteries was annually monitored by high-resolution ultrasonography in seven bilateral upper extremity transplant (UET) patients. We also investigated the IMT of seven matched healthy subjects (controls). No significant difference between IMT values of controls and UET patients was found. The median IMT values of recipient radial and ulnar arteries were 0.23 mm and 0.25 mm, respectively, while the median IMT values of grafted radial and ulnar arteries were 0.27 mm and 0.30 mm, respectively. There was a statistically significant difference in the IMT values of the grafted and recipient ulnar arteries (p = .043), but this difference was no longer significant when patient #2 was excluded. He showed a significant difference between recipient and grafted arteries and significantly higher IMT values (p = .001) of his grafted arteries compared with those of all transplanted patients. This patient developed GV leading to graft loss 11 years after the transplantation. In conclusion, this study showed a significant IMT increase in an UET recipient who developed GV.

Current and future regulatory and financial challenges in vascularized composite allotransplantation

PURPOSE OF REVIEW

To discuss current and future regulatory and financial issues affecting the field of vascularized composite allotransplantation (VCA).

RECENT FINDINGS

Vascularized composite allografts are regulated by the US Department of Health and Human Services Organ Procurement and Transplantation Network Final Rule (42 CFR part 121) in the United States and Directive 2010/53/EU of the European Parliament and the Council of 7 July 2010 in the European Union (EU). However, in the United States and most of the EU, VCA is not yet paid for by insurance or third-party payers and many centers depend upon grant funding, philanthropic gifts, and/or supplemental hospital/institutional funding strategies to pay for the transplants and postoperative care.

SUMMARY

In the absence of randomized clinical trial data, which is infeasible for studying VCA outcomes, consensus data sets are needed to document these procedures' value proposition and have them accepted as part of the standard of care. Procedure and immunosuppression protocol variability applied to a small patient cohort necessitates collaborative efforts by field experts to devise creative approaches, such as determining return-on-investment for anatomical subunits, to better understand these transplants' value and impact on patient quality-of-life.

Pattern of organ remodeling in chronic non-communicable diseases is due to endogenous regulations and falls under the category of Kauffman's self-organization: A case of arterial neointimal pathology

Clinical diagnosis is based on analysis of pathologic findings that may result in perceived patterns. The same is true for diagnostic pathology: Pattern analysis is a foundation of the histopathology-based diagnostic system and, in conjunction with clinical and laboratory findings, forms a basis for the classification of diseases. Any histopathology diagnosis is based on the explicit assumption that the same diseased condition should result in formation of the same (or highly similar) morphologic patterns in different individuals; it is a standard approach in microscopic pathology, including that of non-communicable chronic diseases with organ remodeling. During fifty years of examining diseased tissues under microscopy, I keep asking the same question: Why is a similarity of patterns expected for chronic organ remodeling? For infection diseases, xenobiotic toxicity and deficiencies forming an identical pathologic pattern in different individuals is understandable and logical: The same infection, xenobiotic, or deficiency strikes the same target, which results in identical pathology. The same is true for Mendelian diseases: The same mutations lead to the same altered gene expressions and the same pathologic pattern. But why does this regularity hold true for chronic diseases with organ remodeling? Presumable causes (or risk factors) for a particular chronic disease differ in magnitude and duration between individuals, which should result in various series of transformations. Yet, mysteriously enough, pathological remodeling in a particular chronic disease always falls into a main dominating pattern, perpetuating and progressing in a similar fashion in different patients. Furthermore, some chronic diseases of different etiologies and dissimilar causes/risk factors manifest as identical or highly similar patterns of pathologic remodeling. HYPOTHESIS: I hypothesize that regulations governing a particular organ's chronic remodeling were selected in evolution as the safest response to various insults and physiologic stress conditions. This hypothesis implies that regulations directing diseased chronic remodeling always preexist but normally are controlled; this control can be disrupted by a diverse range of non-specific signals, liberating the pathway for identical pathologic remodeling. This hypothesis was tested in an analysis of arterial neointimal formation, the identical pathology occurring in different diseases and pathological conditions: graft vascular disease in organ transplantation, in-stent restenosis, peripheral arterial diseases, idiopathic intimal hyperplasia, Kawasaki disease, coronary atherosclerosis and as reaction to drugs. The hypothesis suggests that arterial intimal cells are poised between only two alternative pathways: the pathway with controlled intimal cell proliferation or the pathway where such control is disrupted, ultimately leading to the progressive neointimal pathology. By this property the arterial neointimal formation constitutes a special case of Kauffman's self-organization. This new hypothesis gives a parsimonious explanation for identical pathological patterns of arterial remodeling (neointimal formation), which occurs in diseases of different etiologies and due to dissimilar causes/risk factors, or without any etiology and causes/risk factors at all. This new hypothesis also suggests that regulation facilitating intimal cell proliferation cannot be overwritten or annulled because this feature is vital for arterial differentiation, cell renewal, and integrity. This hypothesis suggests that studying numerous, and likely interchangeable, non-specific signals that disrupt regulation controlling intimal cell proliferation is unproductive; instead, a study of the controlling regulation(s) itself should be a priority of our research.

[Ethics of facial transplantation]

Without revisiting prior experiences, many deviations persist, frequently due to economic interests and many countries are relocating their trials to countries with less stringent regulations. It was therefore legitimate for facial allotransplantation of composite tissues to be the subject of ethical reflection.

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.

Psychosocial dimensions of hand transplantation: lessons learned from solid organ transplantation

PURPOSE OF REVIEW

The present review examines psychosocial factors emerging as predictive of clinical outcomes among solid organ transplant (SOT) recipients, with possible extensions to vascular composite allograft (VCA) and hand transplantation, in particular. The Chauvet Workgroup report and International Society of Heart and Lung Transplantation consensus guidelines are used to delineate areas of commonality between SOT and VCA, as well as unique features contributing to post-VCA psychosocial risk.

RECENT FINDINGS

Increasing evidence suggests that depression, cognitive function, and other posttransplant psychosocial factors consistently associate with clinical risk in SOT. However, the mechanisms precipitating these psychosocial risk factors are likely diverse in their cause, with large individual differences across SOT and VCA. Transdiagnostic dimensions may serve as mechanistic factors, increasing the risk of adverse clinical outcomes and suggesting potential treatment strategies for risk mitigation. Psychosocial dimensions including psychological flexibility, self-efficacy, and posttraumatic growth are discussed as potential contributory factors.

SUMMARY

Psychosocial factors hold importance in predicting posttransplant clinical outcomes. Emerging transdiagnostic factors may provide insight into mechanisms and potential treatments.