Vascularized Composite Allotransplantation Research Articles

Immune modulation in transplant medicine: a comprehensive review of cell therapy applications and future directions.

Balancing the immune response after solid organ transplantation (SOT) and vascularized composite allotransplantation (VCA) remains an ongoing clinical challenge. While immunosuppressants can effectively reduce acute rejection rates following transplant surgery, some patients still experience recurrent acute rejection episodes, which in turn may progress to chronic rejection. Furthermore, these immunosuppressive regimens are associated with an increased risk of malignancies and metabolic disorders. Despite significant advancements in the field, these IS related side effects persist as clinical hurdles, emphasizing the need for innovative therapeutic strategies to improve transplant survival and longevity. Cellular therapy, a novel therapeutic approach, has emerged as a potential pathway to promote immune tolerance while minimizing systemic side-effects of standard IS regiments. Various cell types, including chimeric antigen receptor T cells (CAR-T), mesenchymal stromal cells (MSCs), regulatory myeloid cells (RMCs) and regulatory T cells (Tregs), offer unique immunomodulatory properties that may help achieve improved outcomes in transplant patients. This review aims to elucidate the role of cellular therapies, particularly MSCs, T cells, Tregs, RMCs, macrophages, and dendritic cells in SOT and VCA. We explore the immunological features of each cell type, their capacity for immune regulation, and the prospective advantages and obstacles linked to their application in transplant patients. An in-depth outline of the current state of the technology may help SOT and VCA providers refine their perioperative treatment strategies while laying the foundation for further trials that investigate cellular therapeutics in transplantation surgery.

104. Revolutionizing Vascularized Composite Allotransplantation: A Novel Anastomotic Bypass Technique In Combined Face And Whole-eye Transplantation

104. Revolutionizing Vascularized Composite Allotransplantation: A Novel Anastomotic Bypass Technique In Combined Face And Whole-eye Transplantation

Design of a Multiparametric Perfusion Bioreactor System for Evaluating Sub-Normothermic Preservation of Rat Abdominal Wall Vascularized Composite Allografts.

Static cold storage (SCS), the current clinical gold standard for organ preservation, provides surgeons with a limited window of time between procurement and transplantation. In vascularized composite allotransplantation (VCA), this time limitation prevents many viable allografts from being designated to the best-matched recipients. Machine perfusion (MP) systems hold significant promise for extending and improving organ preservation. Most of the prior MP systems for VCA have been built and tested for large animal models. However, small animal models are beneficial for high-throughput biomolecular investigations. This study describes the design and development of a multiparametric bioreactor with a circuit customized to perfuse rat abdominal wall VCAs. To demonstrate its concept and functionality, this bioreactor system was employed in a small-scale demonstrative study in which biomolecular metrics pertaining to graft viability were evaluated non-invasively and in real time. We additionally report a low incidence of cell death from ischemic necrosis as well as minimal interstitial edema in machine perfused grafts. After up to 12 h of continuous perfusion, grafts were shown to survive transplantation and reperfusion, successfully integrating with recipient tissues and vasculature. Our multiparametric bioreactor system for rat abdominal wall VCA provides an advanced framework to test novel techniques to enhance normothermic and sub-normothermic VCA preservations in small animal models.

Exploring Costimulatory Blockade-Based Immunologic Strategies in Transplantation: Are They a Promising Immunomodulatory Approach for Organ and Vascularized Composite Allotransplantation?

The field of transplantation, including the specialized area of vascularized composite allotransplantation (VCA), has been transformed since the first hand transplant in 1998. The major challenge in VCA comes from the need for life-long immunosuppressive therapy due to its non-vital nature and a high rate of systemic complications. Ongoing research is focused on immunosuppressive therapeutic strategies to avoid toxicity and promote donor-specific tolerance. This includes studying the balance between tolerance and effector mechanisms in immune modulation, particularly the role of costimulatory signals in T lymphocyte activation. Costimulatory signals during T cell activation can have either stimulatory or inhibitory effects. Interfering with T cell activation through costimulation blockade strategies shows potential in avoiding rejection and prolonging the survival of transplanted organs. This review paper aims to summarize current data on the immunologic role of costimulatory blockade in the field of transplantation. It focuses on strategies that can be applied in vascularized composite allotransplantation, offering insights into novel methods for enhancing the success and safety of these procedures.

Case Report: Post-transplant lymphoproliferative disorder as a serious complication of vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is an emerging field in transplant surgery. Despite overall positive outcomes, VCA confers risk for multiple complications related to the procedure and subsequent immunosuppression. Post-transplant lymphoproliferative disorder (PTLD) is a heterogeneous group of lymphoproliferative disorders occurring after solid organ and hematopoietic stem cell transplant. A patient with PTLD after bilateral upper extremity transplantation is presented as well as a review of all known cases of PTLD after VCA, with a focus on the unique epidemiology, presentation, and treatment in this population.

Immunogenicity and tolerance induction in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is the transplantation of multiple tissues such as skin, muscle, bone, nerve, and vessels, as a functional unit (i.e., hand or face) to patients suffering from major tissue trauma and functional deficits. Though the surgical feasibility has been optimized, issues regarding graft rejection remains. VCA rejection involves a diverse population of cells but is primarily driven by both donor and recipient lymphocytes, antigen-presenting cells, macrophages, and other immune as well as donor-derived cells. In addition, it is commonly understood that different tissues within VCA, such as the skin, elicits a stronger rejection response. Currently, VCA recipients are required to follow potent and lifelong immunosuppressing regimens to maximize graft survival. This puts patients at risk for malignancies, opportunistic infections, and cancers, thereby posing a need for less perilous methods of inducing graft tolerance. This review will provide an overview of cell populations and mechanisms, specific tissue involved in VCA rejection, as well as an updated scope of current methods of tolerance induction.

Lymphadenopathy and lymph node rejection following facial vascularized composite allotransplantation

BackgroundApart from the skin, little is known about the immunological processes in deeper tissues, which are typically not accessible to biopsy and inspection, of vascularized composite allografts (VCAs). Face transplant patients develop prominent adenopathy shortly after transplantation that resolves over time. The mechanisms underlying this process are not understood. Materials and methodsA retrospective cohort study was conducted on 9 patients who underwent 10 facial VCAs at the Brigham and Women’s Hospital, Boston, MA, between April 2009 and July 2019. Clinical, radiological, and histological data related to lymphadenopathy of the head and neck were reviewed. ResultsPatients who received donor-derived lymph nodes (LNs) developed bilateral lymphadenopathy of the submental or submandibular superficial LNs. Median time of presentation was POD18 (range POD6-POM3). Notably, bilateral adenopathy of the neck was not observed in later stages of follow-up (mean follow-up, 115 months). Histology of 3 LNs showed increased histiocytes and apoptosis, with the features reminiscent of necrotizing histiocytic lymphadenitis, and B and T lymphocytes (mostly CD8 + T) admixed with CD163 + histiocytes and dendritic cells. Molecular chimerism analysis in one case showed the coexistence of donor (81%) and recipient (19%) derived lymphocytes. Granzyme B (GZMB) expression confirmed the presence of increased cytotoxic T cells in this LN sample. ConclusionOur data suggested the involvement of an immunological process within the donor-derived LNs after facial allotransplantation between the recipient and donor cells. GZMB expression suggested LN rejection that can occurred independently of skin rejection. This finding supports the need to better define the role of donor-derived immune cells in the context of allograft rejection.

Developing online communication training to request donation for vascularized composite allotransplantation (VCA): improving performance to match new US organ donation targets.

Approaching families of dying or newly deceased patients to donate organs requires specialized knowledge and a mastery of relational communication. As the transplantation field has progressed, Donation Professionals (DPs) are also leading conversations with family decision makers (FDMs) about the donation of uncommon anatomical gifts, such as face, hands, genitalia, referred to as Vascularized Composite Allotransplants (VCA) without much training or experience. To address the need for training, we adapted and beta tested an evidenced-based communication training program for donation discussions to VCA requests. The overarching goal of Communicating Effectively about Donation for Vascularized Composite Allotransplantation (CEaD-VCA) is to increase the number of VCA authorizations and to improve the socioemotional outcomes of FDMs. We developed CEaD-VCA, an online, on-demand training program based on the previously tested, evidenced-based communication skills training program designed to train DPs to have conversations about solid organ donation. The training was modified utilizing data from a national telephone survey with DPs and results of 6 focus groups conducted with members of the general public. The survey and focus groups assessed knowledge, attitudes, and barriers to VCA donation. The training was shaped by a partnership with a leading industry partner, the Gift of Life Institute.™ RESULTS: Using the results as a guide, the existing CEaD training program, consisting of interactive eLearning modules, was adapted to include technical information about VCA, foundational communication skills, and two interactive example VCA donation request scenarios to facilitate active learning. Forty-two DPs from two partner Organ Procurement Organizations (OPOs) participated in the beta test of CEaD-VCA. Pre- and post-test surveys assessed the impact of the training. The training was scored highly by DPs in effectiveness and ease of use. This project created a standardized, accessible, and comprehensive training for DPs to communicate about VCA donation. CEaD-VCA is an example of how to develop a communication skills training for difficult conversations utilizing input from stakeholders, guided by communication theory. It also demonstrates how gaps in communication skills during medical education can be filled utilizing advanced online Learning Management Systems. The training specifically addresses new CMS rules concerning OPO performance metrics.

First-in-Human Whole-Eye Transplantation: Ensuring an Ethical Approach to Surgical Innovation

As innovations in the field of vascular composite allotransplantation (VCA) progress, whole-eye transplantation (WET) is poised to transition from non-human mammalian models to living human recipients. Present treatment options for vision loss are generally considered suboptimal, and attendant concerns ranging from aesthetics and prosthesis maintenance to social stigma may be mitigated by WET. Potential benefits to WET recipients may also include partial vision restoration, psychosocial benefits related to identity and social integration, improvements in physical comfort and function, and reduced surgical risk associated with a biologic eye compared to a prosthesis. Perioperative and postoperative risks of WET are expected to be comparable to those of facial transplantation (FT), and may be similarly mitigated by immunosuppressive protocols, adequate psychosocial support, and a thorough selection process for both the recipient and donor. To minimize the risks associated with immunosuppressive medications, the first attempts in human recipients will likely be performed in conjunction with a FT. If first-in-human attempts at combined FT-WET prove successful and the biologic eye survives, this opens the door for further advancement in the field of vision restoration by means of a viable surgical option. This analysis integrates recent innovations in WET research with the existing discourse on the ethics of surgical innovation and offers preliminary guidance to VCA programs considering undertaking WET in human recipients.

Incorporating Trauma-informed Approaches to Care in Vascularized Composite Allotransplantation.

Since 1998, vascularized composite allotransplantation (VCA) has been a growing area of research in the field of reconstructive surgery. Although conditions treated with VCA often result from a traumatic injury, there has been limited emphasis on incorporating trauma-informed care (TIC) models in VCA. Considering the importance of psychosocial well-being in VCA candidates and recipients, applying best practices in TIC to the face, upper extremity, and penile transplantation may be critical in minimizing retraumatization throughout the perioperative process. There are six main principles of TIC: safety; trustworthiness and transparency; peer support; collaboration and mutuality; empowerment and choice; and cultural, historical, and gender issues, which may be further incorporated in care for VCA patients. Evaluating for PTSD and incorporating TIC may have substantial benefit to postoperative outcomes.

Review of machine perfusion studies in vascularized composite allotransplant preservation

The applications of Vascularized composite allotransplantation (VCA) are increasing since the first successful hand transplantation in 1998. However, the abundance of muscle tissue makes VCA's vulnerable to ischemia-reperfusion injury (IRI), which has detrimental effects on the outcome of the procedure, restricting allowable donor-to-recipient time and limiting its widespread use. The current clinical method is Static cold storage (SCS) and this allows only 6 h before irreversible damage occurs upon reperfusion. In order to overcome this obstacle, the focus of research has been shifted towards the prospect of ex-vivo perfusion preservation which already has an established clinical role in solid organ transplants especially in the last decade. In this comprehensive qualitative review, we compile the literature on all VCA machine perfusion models and we aim to highlight the essentials of an ex vivo perfusion set-up, the different strategies, and their associated outcomes.

Surgical Feasibility Study on Cadaver for Vascularized Wrist Joint Transplantation

Despite modern advancements in the treatment of late stages of wrist joint degeneration, few reliable options exist for patients requiring motion-preserving reconstruction of their radiocarpal and midcarpal joints. Vascularized composite allotransplantation (VCA) could be considered an option for wrist reconstruction in the future. The goal of this study was to describe the relevant anatomy and design a potential surgical technique for wrist VCA. Anatomic studies were performed on 17 human upper extremities. The arterial system of each cadaver was injected with latex dye or radiographic contrast. After injecting a contrast medium visible on a computerized tomography (CT) scan, the initial three specimens were examined using microCT. This confirmed joint vascular patency and allowed for the dissection of the other specimens that were injected with latex for the study of joint vascularization and the design of the wrist VCA. We then outlined a donor and recipient surgical technique for transplant based on recipient CT scans. Customized cutting guides were designed for the transplant procedure. After the procedure, we performed angiography of the VCA to determine the vascularity of the transplant. Using a combined volar and dorsal approach, we were able to perform a complete wrist VCA procedure. After the completed transplant procedure, angiographic imaging of the specimens demonstrated that the flap dissection and transplantation preserved the nutrient endosteal supply to the distal end of the radius and ulna, as well as to the carpal bones and the metacarpal bases. The dissection of the donor, recipient, and the entire vascularized joint transplant procedure served to illustrate the anatomical feasibility of the cadaveric surgical technique. This establishes an anatomic basis for the possibility of future human clinical applications. This study helps investigate the anatomical feasibility of a wrist VCA.

Mimicking Clinical Rejection Patterns in a Rat Osteomyocutaneous Flap Model of Vascularized Composite Allotransplantation

IntroductionGraft loss in vascularized composite allotransplantation (VCA) is more often associated with vasculopathy and chronic rejection (CR) than acute cellular rejection (ACR). We present a rat osteomyocutaneous flap model using titrated tacrolimus administration that mimics the graft rejection patterns in our clinical hand transplant program. Comparison of outcomes in these models support a role for ischemia reperfusion injury (IRI) and microvascular changes in CR of skin and large-vessel vasculopathy. The potential of the surgical models for investigating mechanisms of rejection and vasculopathy in VCA and treatment interventions is presented. Materials and MethodsFour rodent groups were evaluated: syngeneic controls (Group 1), allogeneic transient immunosuppression (Group 2), allogeneic suboptimal immunosuppression (Group 3), and allogeneic standard immunosuppression (Group 4). Animals were monitored for ACR, vasculopathy, and CR of the skin. ResultsTransient immunosuppression resulted in severe ACR within 2 wk of tacrolimus discontinuation. Standard immunosuppression resulted in minimal rejection but subclinical microvascular changes, including capillary thrombosis and luminal narrowing in arterioles in the donor skin. Further reduction in tacrolimus dose led to femoral vasculopathy and CR of the skin. Surprisingly, femoral vasculopathy was also observed in the syngeneic control group. ConclusionsTitration of tacrolimus in the allogeneic VCA model resulted in presentations of rejection and vasculopathy similar to those in patients and suggests vasculopathy starts at the microvascular level. This adjustable experimental model will allow the study of variables and interventions, such as external trauma or complement blockade, that may initiate or mitigate vasculopathy and CR in VCA.

Application possibilities of artificial intelligence in facial vascularized composite allotransplantation-a narrative review.

Facial vascularized composite allotransplantation (FVCA) is an emerging field of reconstructive surgery that represents a dogmatic shift in the surgical treatment of patients with severe facial disfigurements. While conventional reconstructive strategies were previously considered the goldstandard for patients with devastating facial trauma, FVCA has demonstrated promising short- and long-term outcomes. Yet, there remain several obstacles that complicate the integration of FVCA procedures into the standard workflow for facial trauma patients. Artificial intelligence (AI) has been shown to provide targeted and resource-effective solutions for persisting clinical challenges in various specialties. However, there is a paucity of studies elucidating the combination of FVCA and AI to overcome such hurdles. Here, we delineate the application possibilities of AI in the field of FVCA and discuss the use of AI technology for FVCA outcome simulation, diagnosis and prediction of rejection episodes, and malignancy screening. This line of research may serve as a fundament for future studies linking these two revolutionary biotechnologies.

Vascularized Composite Allograft Versus Prosthetic for Reconstruction After Facial and Hand Trauma: Comparing Cost, Complications, and Long-term Outcome.

In the past decade, vascularized composite allotransplantation (VCA) has become clinical reality for reconstruction after face and hand trauma. It offers patients the unique opportunity to regain form and function in a way that had only been achieved with traditional reconstruction or with the use of prostheses. On the other hand, prostheses for facial and hand reconstruction have continued to evolve over the years and, in many cases, represent the primary option for patients after hand and face trauma. We compared the cost, associated complications, and long-term outcomes of VCA with prostheses for reconstruction of the face and hand/upper extremity. Ultimately, VCA and prostheses represent 2 different reconstructive options with distinct benefit profiles and associated limitations and should ideally not be perceived as competing choices. Our work adds a valuable component to the general framework guiding the decision to offer VCA or prostheses for reconstruction after face and upper extremity trauma.

Supercooling: A Promising Technique for Prolonged Organ Preservation in Solid Organ Transplantation, and Early Perspectives in Vascularized Composite Allografts.

Ex-vivo preservation of transplanted organs is undergoing spectacular advances. Machine perfusion is now used in common practice for abdominal and thoracic organ transportation and preservation, and early results are in favor of substantially improved outcomes. It is based on decreasing ischemia-reperfusion phenomena by providing physiological or sub-physiological conditions until transplantation. Alternatively, supercooling techniques involving static preservation at negative temperatures while avoiding ice formation have shown encouraging results in solid organs. Here, the rationale is to decrease the organ's metabolism and need for oxygen and nutrients, allowing for extended preservation durations. The aim of this work is to review all advances of supercooling in transplantation, browsing the literature for each organ. A specific objective was also to study the initial evidence, the prospects, and potential applications of supercooling preservation in Vascularized Composite Allotransplantation (VCA). This complex entity needs a substantial effort to improve long-term outcomes, marked by chronic rejection. Improving preservation techniques is critical to ensure the favorable evolution of VCAs, and supercooling techniques could greatly participate in these advances.

RNA Sequencing Reveals a Conserved Mechanism of T Cell-Mediated Rejection in Vascularized Composite Allotransplantation Across Anatomical Sites

RNA Sequencing Reveals a Conserved Mechanism of T Cell-Mediated Rejection in Vascularized Composite Allotransplantation Across Anatomical Sites

A Single Cell and Spatial Transcriptomics Approach to Elucidating CD8 T Cells in Vascularized Composite Allotransplantation Rejection

A Single Cell and Spatial Transcriptomics Approach to Elucidating CD8 T Cells in Vascularized Composite Allotransplantation Rejection

The synergistic effect of full-spectrum light therapy and transient immunosuppressants prolonged allotransplant survival.

The lifelong administration of immunosuppressants remains its largest drawback in vascularized composite allotransplantation (VCA). Therefore, developing alternative strategies to minimize the long-term use of immunosuppressive agents is crucial. This study investigated whether full-spectrum bright light therapy (FBLT) combined with short-term immunosuppressant therapy could prolong VCA survival in a rodent hindlimb model. Hindlimb allotransplantation was conducted from Brown-Norway to Lewis rats, and the rats were divided into 4 groups. Group 1 did not receive treatment as a rejection control. Group 2 received FBLT alone. Group 3 was treated with short-term anti-lymphocyte serum and cyclosporine-A. Group 4 was administered short-term ALS/CsA combined with FBLT for 8 weeks. Peripheral blood and transplanted tissues were collected for analysis. The results revealed median survival time of FBLT alone (group 2) did not increase allograft survival compared to the control (group 1). However, group 4 with FBLT combined with short-term ALS/CsA significantly prolonged median composite tissue allograft survival time (266 days) compared with groups 1 (11 days), 2 (10 days), and 3 (41 days) (p<0.01). Group 4 also showed a significant increase in Treg cells (p = 0.04) and TGF-β1 levels (p = 0.02), and a trend toward a decrease in IL-1β levels (p = 0.03) at 16 weeks after transplantation as compared to control Group 1. FBLT combined with short-term immunosuppressants prolonged allotransplant survival by modulating T-cell regulatory functions and anti-inflammatory cytokine expression. This approach could be a potential strategy to increase VCA survival.

Novel cell-based strategies for immunomodulation in vascularized composite allotransplantation.

Vascularized composite allotransplantation (VCA) has become a clinical reality in the past two decades. However, its routine clinical applications are limited by the risk of acute rejection, and the side effects of the lifelong immunosuppression. Therefore, there is a need for new protocols to induce tolerance and extend VCA survival. Cell- based therapies have emerged as an attractive strategy for tolerance induction in VCA. This manuscript reviews the current strategies and applications of cell-based therapies for tolerance induction in VCA. Cellular therapies, including the application of bone marrow cells (BMC), mesenchymal stem cells (MSC), adipose stem cells, regulatory T cells (Treg) cells, dendritic cells and donor recipient chimeric cells (DRCC) show promising potential as a strategy to induce tolerance in VCA. Ongoing basic science research aims to provide insights into the mechanisms of action, homing, functional specialization and standardization of these cellular therapies. Additionally, translational preclinical and clinical studies are underway, showing encouraging outcomes. Cellular therapies hold great potential and are supported by preclinical studies and clinical trials demonstrating safety and efficacy. However, further research is needed to develop novel cell-based immunosuppressive protocol for VCA.