Hand Transplantation: Current Status and Immunologic Obstacles

Transcriptome profiling of immune rejection mechanisms in a porcine vascularized composite allotransplantation model

Background

Vascularized composite allotransplantation (VCA) offers the potential for a biological, functional reconstruction in individuals with limb loss or facial disfigurement. Yet, it faces substantial challenges due to heightened immune rejection rates compared to solid organ transplants. A deep understanding of the genetic and immunological drivers of VCA rejection is essential to improve VCA outcomes.

Methods

Heterotopic porcine hindlimb VCA models were established and followed until reaching the endpoint. Skin and muscle samples were obtained from VCA transplant recipient pigs for histological assessments and RNA sequencing analysis. The rejection groups included recipients with moderate pathological rejection, treated locally with tacrolimus encapsulated in triglycerol-monostearate gel (TGMS-TAC), as well as recipients with severe end-stage rejection presenting evident necrosis. Healthy donor tissue served as controls. Bioinformatics analysis, immunofluorescence, and electron microscopy were utilized to examine gene expression patterns and the expression of immune response markers.

Results

Our comprehensive analyses encompassed differentially expressed genes, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathways, spanning various composite tissues including skin and muscle, in comparison to the healthy control group. The analysis revealed a consistency and reproducibility in alignment with the pathological rejection grading. Genes and pathways associated with innate immunity, notably pattern recognition receptors (PRRs), damage-associated molecular patterns (DAMPs), and antigen processing and presentation pathways, exhibited upregulation in the VCA rejection groups compared to the healthy controls. Our investigation identified significant shifts in gene expression related to cytokines, chemokines, complement pathways, and diverse immune cell types, with CD8 T cells and macrophages notably enriched in the VCA rejection tissues. Mechanisms of cell death, such as apoptosis, necroptosis and ferroptosis were observed and coexisted in rejected tissues.

Conclusion

Our study provides insights into the genetic profile of tissue rejection in the porcine VCA model. We comprehensively analyze the molecular landscape of immune rejection mechanisms, from innate immunity activation to critical stages such as antigen recognition, cytotoxic rejection, and cell death. This research advances our understanding of graft rejection mechanisms and offers potential for improving diagnostic and therapeutic strategies to enhance the long-term success of VCA.

Challenges and opportunities in vascularized composite allotransplantation of joints: a systematic literature review

Background

Joint allotransplantation (JA) within the field of vascularized composite allotransplantation (VCA) holds great potential for functional and non-prosthetic reconstruction of severely damaged joints. However, clinical use of JA remains limited due to the immune rejection associated with all forms of allotransplantation. In this study, we aim to provide a comprehensive overview of the current state of JA through a systematic review of clinical, animal, and immunological studies on this topic.

Methods

We conducted a systematic literature review in accordance with the PRISMA guidelines to identify relevant articles in PubMed, Cochrane Library, and Web of Science databases. The results were analyzed, and potential future prospects were discussed in detail.

Results

Our review included 14 articles describing relevant developments in JA. Currently, most JA-related research is being performed in small animal models, demonstrating graft survival and functional restoration with short-term immunosuppression. In human patients, only six knee allotransplantations have been performed to date, with all grafts ultimately failing and a maximum graft survival of 56 months.

Conclusion

Research on joint allotransplantation has been limited over the last 20 years due to the rarity of clinical applications, the complex nature of surgical procedures, and uncertain outcomes stemming from immune rejection. However, the key to overcoming these challenges lies in extending graft survival and minimizing immunosuppressive side effects. With the emergence of new immunosuppressive strategies, the feasibility and clinical potential of vascularized joint allotransplantation warrants further investigation.

Cellular activation pathways and interaction networks in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is an evolving field of reconstructive surgery that has revolutionized the treatment of patients with devastating injuries, including those with limb losses or facial disfigurement. The transplanted units are typically comprised of different tissue types, including skin, mucosa, blood and lymphatic vasculature, muscle, and bone. It is widely accepted that the antigenicity of some VCA components, such as skin, is particularly potent in eliciting a strong recipient rejection response following transplantation. The fine line between tolerance and rejection of the graft is orchestrated by different cell types, including both donor and recipient-derived lymphocytes, macrophages, and other immune and donor-derived tissue cells (e.g., endothelium). Here, we delineate the role of different cell and tissue types during VCA rejection. Rejection of VCA grafts and the necessity of life-long multidrug immunosuppression remains one of the major challenges in this field. This review sheds light on recent developments in decoding the cellular signature of graft rejection in VCA and how these may, ultimately, influence the clinical management of VCA patients by way of novel therapies that target specific cellular processes.

Hand Therapy Regimen for Functional Recovery Following Combined Face and Bilateral Hand Transplantation

Intensive postoperative rehabilitation therapy is associated with positive functional recovery in hand transplants (HTs). Our goal is to share the hand therapy protocol developed for our patient who underwent a combined face and bilateral HT. The patient is a 23-year-old right-hand-dominant male with a history of third-degree burns to 80% of his body following a motor vehicle accident. A multidisciplinary evaluation established his candidacy for a combined face and bilateral HT, and surgery took place in August 2020. Our individualized hand therapy protocol consisted of 4 phases. The pre-surgery phase focused on planning the orthotics and patient/caregivers' education on the rehabilitation process. The intensive care unit (ICU)/acute care phase involved hand allograft protection and positioning via orthotic fabrication, safe limb handling, and edema/wound management. The inpatient rehabilitation phase aimed to prepare the patient for independent living via neuromuscular and sensory re-education, improvement of upper extremities strength/flexibility, training basic activities of daily living, and providing a home exercise program (HEP). Finally, the outpatient phase aimed to maximize our patient's range of motion and independency in performing his routine activities and HEP. The patient's post-transplant functional outcomes showed a significant improvement compared to the pre-operative baseline. We hope this report sheds light on a comprehensive hand therapy program in HT.

IL-10 modified mRNA monotherapy prolongs survival after composite facial allografting through the induction of mixed chimerism

Vascularized composite allotransplantation has great potential in face transplantation by supporting functional restoration following tissue grafting. However, the need for lifelong administration of immunosuppressive drugs still limits its wide use. Modified mRNA (modRNA) technology provides an efficient and safe method to directly produce protein in vivo. Nevertheless, the use of IL-10 modRNA-based protein replacement, which exhibits anti-inflammatory properties, has not been shown to prolong composite facial allograft survival. In this study, IL-10 modRNA was demonstrated to produce functional IL-10 protein in vitro, which inhibited pro-inflammatory cytokines and in vivo formation of an anti-inflammatory environments. We found that without any immunosuppression, C57BL/6J mice with fully major histocompatibility complex (MHC)-mismatched facial allografts and local injection of IL-10 modRNA had a significantly prolonged survival rate. Decreased lymphocyte infiltration and pro-inflammatory T helper 1 subsets and increased anti-inflammatory regulatory T cells (Tregs) were seen in IL-10 modRNA-treated mice. Moreover, IL-10 modRNA induced multilineage chimerism, especially the development of donor Treg chimerism, which protected allografts from destruction because of recipient alloimmunity. These results support the use of monotherapy based on immunomodulatory IL-10 cytokines encoded by modRNA, which inhibit acute rejection and prolong allograft survival through the induction of donor Treg chimerism.

A Systematic Review of the Reported Complications Related to Facial and Upper Extremity Vascularized Composite Allotransplantation

INTRODUCTION

Twenty three years after the first successful upper extremity transplantation, the role of vascularized composite allotransplantation (VCA) in the world of transplantation remains controversial. Face and upper extremity reconstruction via transplantation have become successful options for highly selected patients with severe tissue and functional deficit when conventional reconstructive options are no longer available. Despite clear benefit in these situations, VCA has a significant potential for complications that are more frequent when compared to visceral organ transplantation. This study intended to perform an updated systematic review on such complications.

MATERIALS AND METHODS

MEDLINE database via PubMed, Embase and Cochrane Library were searched. Face and upper extremity VCA performed between 1998 and 2021 were included in the study. Relevant media and press conferences reports were also included. Complications related to face and upper extremity VCA were recorded and reviewed including their clinical characteristics and complications.

RESULTS

One hundred fifteen patients underwent facial (43%) or upper extremity (57%) transplantation. Overall, the surgical complication rate was 23%. Acute and chronic rejection was identified in 89% and 11% of patients, respectively. Fifty eight percent of patients experienced opportunistic infection. Impaired glucose metabolism was the most common immunosuppression-related complication other than infection. Nineteen percent of patients ultimately experienced partial or complete allograft loss.

CONCLUSIONS

Complications related to VCA are a significant source of morbidity and potential mortality. Incidence of such complications is higher than previously reported and should be strongly emphasized in patient consent process. Strict patient selection criteria, complex preoperative evaluation, consideration of alternatives, and thorough disclosure to patients should be routinely performed prior to VCA indication.

Applying Health Utility Outcome Measures and Quality-Adjusted Life-Years to Compare Hand Allotransplantation and Myoelectric Prostheses for Upper Extremity Amputations

BACKGROUND

An amputation of the upper extremity not only is devastating for the patient's physical, emotional, and social well-being but also constitutes a financial stress for both the patient and the health care system. The objective of this study was to determine the utility and quality-adjusted life-years of hand allotransplantation versus myoelectric prostheses and to compare these measures in patients afflicted with unilateral versus bilateral amputations.

METHODS

A survey was administered on bilateral amputees, unilateral amputees, replantation patients, and healthy controls. Patient demographics, functional patient-reported outcomes, quality-of-life questionnaires, and utility outcome measures were calculated for four different scenarios: hand transplantation and myoelectric prostheses with or without complications.

RESULTS

Five bilateral amputees, 12 unilateral amputees, nine replantation patients, and 45 healthy controls completed the survey. The highest quality-adjusted life-years were obtained in the replantation patient group for the scenario of myoelectric prosthesis without complications (mean, 34.8 years). Altogether, there was no statistically significant difference between hand transplantation and myoelectric prostheses (p = 0.36). On subgroup analysis, unilateral amputees reported significantly higher quality-adjusted life-years for myoelectric prostheses rather than hand transplantation (6.4; p = 0.0015), whereas bilateral amputees did not demonstrate a significant difference (-2.4; p = 0.299).

CONCLUSIONS

Utility and quality-adjusted life-years do not differ significantly between hand transplantation and myoelectric prostheses, except in unilateral amputees with myoelectric prostheses, who had higher quality-of-life scores. Based on trends from this pilot study, myoelectric prostheses may be considered for unilateral amputees, whereas no superiority can be demonstrated between both treatments in bilateral amputees.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Descriptive Study of Patients With Upper Limb Amputation As Possible Candidates for a Hand Transplant in Medellín, Colombia

Introduction

The amputation of the upper limb, especially of the hand, is a serious trauma with significant functional and psychological impact. Treatment options include adaptation to the stump, use of prostheses, and composite tissue transplantation. Unfortunately, in Colombia, to date, there are no epidemiological data that characterize the sociodemographic and clinical variables of patients with upper limb amputation.

Objective

To describe the clinical and epidemiological characteristics of patients with upper limb amputation in two hospital institutions in the city of Medellín during the period 2018-2019 as a basis for developing a hand transplant program in Colombia.

Methods

A descriptive cross-sectional study was carried out where a total of 443 medical records were reviewed, of which eight records that met the inclusion criteria were identified. Variables such as age, etiology of amputation, level of amputation, comorbidities, complications, and rehabilitation process were analyzed. The information was collected in the REDCap program, and a descriptive analysis was carried out with the data obtained.

Results

From a sample of 443 amputee patients, eight were selected that met the inclusion criteria. There were 7/8 men (87%) aged 43 years. A total of 75% came from rural areas. In 3/8 patients, there was amputation of the dominant limb. The most common mechanisms were shear trauma and crushing in the context of an occupational accident. A total of 50% had a complete extra-hospital amputation, and reimplantation was not attempted in any of the cases. The most frequent levels of amputation were the proximal and distal third of the forearm. The longest follow-up time was 12 months. Only two patients mentioned the possibility of using a prosthesis during rehabilitation.

Conclusions

Three young patients were identified, without comorbidities, with amputation of the dominant limb in the context of an occupational accident and without the possibility of rehabilitation with prostheses who benefit from a possible future hand transplant. However, it is necessary to implement a composite tissue transplantation program and public health policies that allow this procedure to be performed in Colombia.

Addressing common orthopaedic calamities with microsurgical solutions

Reconstructive microsurgery has been an essential aspect of orthopaedic surgery and extremity reconstruction since the introduction of the operating microscope in the mid-20^th century. The reconstructive ladder ranges from simple healing by secondary intention to complex procedures such as free tissue transfer and vascularized composite allotransplantation. As orthopaedic surgery has evolved over the past 60 years, so too have the reconstructive microsurgical skills that are often needed to address common orthopaedic surgery problems. In this article, we will discuss a variety of complex orthopaedic surgery scenarios ranging from trauma to infection to tumor resection as well as the spectrum of microsurgical solutions that can aid in their management.

The Mandible Ameliorates Facial Allograft Rejection and Is Associated with the Development of Regulatory T Cells and Mixed Chimerism

Vascularized composite allografts contain various tissue components and possess relative antigenicity, eliciting different degrees of alloimmune responses. To investigate the strategies for achieving facial allograft tolerance, we established a mouse hemiface transplant model, including the skin, muscle, mandible, mucosa, and vessels. However, the immunomodulatory effects of the mandible on facial allografts remain unclear. To understand the effects of the mandible on facial allograft survival, we compared the diversities of different facial allograft-elicited alloimmunity between a facial osteomyocutaneous allograft (OMC), including skin, muscle, oral mucosa, and vessels, and especially the mandible, and a myocutaneous allograft (MC) including the skin, muscle, oral mucosa, and vessels, but not the mandible. The different facial allografts of a BALB/c donor were transplanted into a heterotopic neck defect on fully major histocompatibility complex-mismatched C57BL/6 mice. The allogeneic OMC (Allo-OMC) group exhibited significant prolongation of facial allograft survival compared to the allogeneic MC group, both in the presence and absence of FK506 immunosuppressive drugs. With the use of FK506 monotherapy (2 mg/kg) for 21 days, the allo-OMC group, including the mandible, showed prolongation of facial allograft survival of up to 65 days, whereas the myocutaneous allograft, without the mandible, only survived for 34 days. The Allo-OMC group also displayed decreased lymphocyte infiltration into the facial allograft. Both groups showed similar percentages of B cells, T cells, natural killer cells, macrophages, and dendritic cells in the blood, spleen, and lymph nodes. However, a decrease in pro-inflammatory T helper 1 cells and an increase in anti-inflammatory regulatory T cells were observed in the blood and lymph nodes of the Allo-OMC group. Significantly increased percentages of donor immune cells were also observed in three lymphoid organs of the Allo-OMC group, suggesting mixed chimerism induction. These results indicated that the mandible has the potential to induce anti-inflammatory effects and mixed chimerism for prolonging facial allograft survival. The immunomodulatory understanding of the mandible could contribute to reducing the use of immunosuppressive regimens in clinical face allotransplantation including the mandible.

Infectious complications of vascularized composite allograft transplantation

PURPOSE OF REVIEW

Vascularized composite allograft (VCA) transplants constitute multiple tissues transplanted together as one functional unit. These procedures are increasing in frequency and complexity, yet data about graft survival, quality of life, and infection risk remain limited.

RECENT FINDINGS

Informative guidance for this patient population is often inferred from the solid organ transplantation literature. Yet, it is important to understand that VCA transplantation additionally carries its own significant and distinctive risk factors for infection.

SUMMARY

In this review, we give an overview of previously described infectious complications of VCA transplantation in the literature, discuss risk factors for future infection in these patients, and discuss how to manage such obstacles.

The Leeds hand transplant programme: Review of the laboratory management of the first six cases

The UK hand transplantation programme is hosted by the Department of Plastic and Reconstructive Surgery at Leeds Teaching Hospitals under the leadership of Professor Simon Kay. Since programme launch in 2013, ten procedures in six individuals have been performed involving unilateral or bilateral transplants. The multi-disciplinary team that delivers the programme includes the transplant immunology service. The laboratory experience in programme support is reported here.

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.