Vascularized composite allografts and solid organ transplants: similarities and differences

Development of a Porcine VCA Model Using an External Iliac Vessel-Based Vertical Rectus Abdominus Myocutaneous Flap

BACKGROUND

 Vascularized composite allotransplantation (VCA) involves transplanting a functional and anatomically complete tissue graft, such as a hand or face, from a deceased donor to a recipient. Although clinical VCA has resulted in successful outcomes, high rates of acute rejection and increased requirements for immunosuppression have led to significant long-term complications. Of note, immunosuppressed graft recipients are predisposed to infections, organ dysfunction, and malignancies. The long-term success of VCA grafts requires the discovery and implementation of unique approaches that avoid these complications altogether. Here, we describe our surgical technique and initial experience with a reproducible heterotopic porcine VCA model for the preclinical assessment of approaches to improve graft outcomes.

METHODS

 Six heterotopic porcine allogeneic vertical rectus abdominis myocutaneous flap transplants were performed using Sinclair donors and Yucatan recipients. Immunosuppressive therapy was not used. Each flap was based on the left external iliac vessel system. Animals were followed postoperatively for surgery-related complications.

RESULTS

 The six pigs underwent successful VCA and were euthanized at the end of the study. Each flap demonstrated complete survival following vessel anastomosis. For the allogeneic recipients, on average, minimal erythema and healthy flap color were observed from postoperative days 1 to 4. There were no surgery-related animal deaths or complications.

CONCLUSION

 We have developed a reproducible, technically feasible heterotopic porcine VCA model based on the left external iliac vessel system. Our results demonstrate this model's potential to improve VCA graft outcomes by exploring tolerance induction and rejection biomarker discovery in preclinical studies.

C-reactive protein orchestrates acute allograft rejection in vascularized composite allotransplantation via selective activation of monocyte subsets

INTRODUCTION

Despite advancements in transplant immunology and vascularized composite allotransplantation (VCA), the longevity of allografts remains hindered by the challenge of allograft rejection. The acute-phase response, an immune-inflammatory reaction to ischemia/reperfusion that occurs directly after allogeneic transplantation, serves as a catalyst for graft rejection. This immune response is orchestrated by acute-phase reactants through intricate crosstalk with the mononuclear phagocyte system.

OBJECTIVE

C-reactive protein (CRP), a well-known marker of inflammation, possesses pro-inflammatory properties and exacerbates ischemia/reperfusion injury. Thus, we investigated how CRP impacts acute allograft rejection.

METHODS

Prompted by clinical observations in facial VCAs, we employed a complex hindlimb transplantation model in rats to investigate the direct impact of CRP on transplant rejection.

RESULTS

Our findings demonstrate that CRP expedites allograft rejection and diminishes allograft survival by selectively activating non-classical monocytes. Therapeutic stabilization of CRP abrogates this activating effect on monocytes, thereby attenuating acute allograft rejection. Intravital imagining of graft-infiltrating, recipient-derived monocytes during the early phase of acute rejection corroborated their differential regulation by CRP and their pivotal role in driving the initial stages of graft rejection.

CONCLUSION

The differential activation of recipient-derived monocytes by CRP exacerbates the innate immune response and accelerates clinical allograft rejection. Thus, therapeutic targeting of CRP represents a novel and promising strategy for preventing acute allograft rejection and potentially mitigating chronic allograft rejection.

The Future of Microsurgery: Vascularized Composite Allotransplantation and Engineering Vascularized Tissue

Background

Microsurgical techniques have revolutionized the field of reconstructive surgery and are the mainstay for complex soft tissue reconstruction. However, their limitations have promoted the development of viable alternatives. This article seeks to explore technologies that have the potential of revolutionizing microsurgical reconstruction as it is currently known, reflect on current and future vascularized composite allotransplantation (VCA) practices, as well as describe the basic science within emerging technologies and their potential translational applications.

Methods

A literature review was performed of the technologies that may represent the future of microsurgery: vascularized tissue engineering (VCA) and flap-specific tissue engineering.

Results

VCA has shown great promise and has already been employed in the clinical setting (especially in face and limb transplantation). Immunosuppression, logistics, cost, and regulatory pathways remain barriers to overcome to make it freely available. Vascularized and flap-specific tissue engineering remain a laboratory reality but have the potential to supersede VCA. The capability of creating an off-the-shelf free flap matching the required tissue, size, and shape is a significant advantage. However, these technologies are still at the early stage and require significant advancement before they can be translated into the clinical setting.

Conclusion

VCA, vascularized tissue engineering, and flap-specific bioengineering represent possible avenues for the evolution of current microsurgical techniques. The next decade will elucidate which of these three strategies will evolve into a tangible translational option and hopefully bring a paradigm shift of reconstructive surgery.

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.

Knowledge mapping and emerging trends of ferroptosis in ischemia reperfusion injury research: A bibliometric analysis (2013-2022)

Objective

Ischemia/reperfusion (I/R) injury is an inevitable dilemma when previously ischemic multiple organs and tissues are returned to a state of blood flow, with confirming a critical role of ferroptosis in molecular, pathway mechanisms, subcellular structure. Discovering the potential relationship may provide useful approaches for the clinical treatment and prognosis of the pathophysiological status of IRI. Therefore, a comprehensive visualization and scientometric analysis were conducted to systematically summarize and discuss the "ferroptosis in ischemia reperfusion injury" research to demonstrate directions for scholars in this field.

Methods

We retrieved all publications focusing on I/R injury and ferroptosis from the Web of Science Core Collection (WoSCC), published from 2013 to October 2022. Next, scientometric analysis of different items was performed using various bibliometrics softwares to explore the annual trends, countries/regions, institutions, journals, authors and their multi-dimensional relationship pointing to current hotspots and future advancement in this field.

Results

We included a total of 421 English articles in set timespan. The number of publications increased steadily annually. China produced the highest number of publications, followed by the United States. Most publications were from Central South University, followed by Sichuan University and Wuhan University. The most authoritative academic journal was Oxidative Medicine and Cellular Longevity. Cell occupied the first rank of co-cited journal list. Andreas Linkermann and Scott J Dixon may have the highest influence in this intersected field with the highest number of citations and co-cited references respectively. The essential biological reactions such as oxidative stress response, lipid peroxidation metabolism, anti-inflammmatory and pro-inflammatory procedure, and related molecular pathways were knowledge base and current hotspots. Molecules pathways exploration, effective inhibition of I/R injury and promising strategy of improving allografts may become future trends and focuses.

Conclusions

Research on ferroptosis in I/R injury had aroused great interest recently. This first bibliometric study comprehensively analyzed the research landscape of ferroptosis and I/R injury, and also provided a reliable reference for related scholars to facilitate further advancement in this field.

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.

In Situ Pre-Treatment of Vascularized Composite Allografts With a Targeted Complement Inhibitor Protects Against Brain Death and Ischemia Reperfusion Induced Injuries

Introduction

Donor brain death (BD) is an unavoidable component of vascularized composite allograft (VCA) transplantation and a key contributor to ischemia-reperfusion injury (IRI). Complement is activated and deposited within solid organ grafts as a consequence of BD and has been shown to exacerbate IRI, although the role of BD and complement in VCA and the role it plays in IRI and VCA rejection has not been studied.

Methods

BD was induced in Balb/c donors, and the VCA perfused prior to graft procurement with UW solution supplemented with or without CR2-Crry, a C3 convertase complement inhibitor that binds at sites of complement activation, such as that induced on the endothelium by induction of BD. Following perfusion, donor VCAs were cold stored for 6 hours before transplantation into C57BL/6 recipients. Donor VCAs from living donors (LD) were also procured and stored. Analyses included CR2-Crry graft binding, complement activation, toxicity, injury/inflammation, graft gene expression and survival.

Results

Compared to LD VCAs, BD donor VCAs had exacerbated IRI and rejected earlier. Following pretransplant in-situ perfusion of the donor graft, CR2-Crry bound within the graft and was retained post-transplantation. CR2-Crry treatment significantly reduced complement deposition, inflammation and IRI as compared to vehicle-treated BD donors. Treatment of BD donor VCAs with CR2-Crry led to an injury profile not dissimilar to that seen in recipients of LD VCAs.

Conclusion

Pre-coating a VCA with CR2-Crry in a clinically relevant treatment paradigm provides localized, and therefore minimally immunosuppressive, protection from the complement-mediated effects of BD induced exacerbated IRI.

Life underneath the VCA umbrella: Perspectives from the US Uterus Transplant Consortium

The parallel emergence of uterus transplantation (UTx) and other transplantation innovations including face and hand transplantation led to the categorization of the uterus as a vascular composite allograft (VCA). With >60 transplants and >20 births worldwide, UTx is transitioning rapidly from a research endeavor to an effective treatment option for women with uterine factor infertility. While it originally made sense to group the innovations under one umbrella, it is time to revisit the designation of UTx as a VCA. We describe how UTx needs unique policy, procedural codes, insurance contracts, and educational initiatives. We contend that separating UTx from VCAs may become necessary in the future to avoid hindering the growth and regulation of this field.

[Immunosuppressive effect of mitomycin C-treated peripheral mononuclear blood cells (MICs) in vascularised composite allotransplantation]

BACKGROUND

Vascularized Composite Allotransplantation (VCA) enables the restoration of complex tissue defects. Since the first successful hand and face transplants were performed, clinical and experimental research has consistently improved immunosuppressive therapies. The incubation of peripheral blood mononuclear cells (PBMCs) with mitomycin C (MMC) results in immunomodulatory cells (MICs). In previous studies, the systemic application of MICs on the day of allogeneic hind limb transplantation led to a significant immunosuppression in rats. The aim of this study is to further investigate the optimal point in time of MIC application in a complex VCA model.

MATERIAL AND METHODS

In six groups, 60 allogeneic hind limb transplantations were performed. Fully mismatched rats were used as hind limb donors [Lewis (LEW)] and recipients [Brown-Norway (BN)]. Group A received donor-derived MICs seven days preoperatively. Group B received no immunosuppression; group C received untreated PBMCs seven days prior to transplantation. Animals in group D received cell culture media, whereas group E was treated with a standard immunosuppression consisting of tacrolimus and prednisolone. In group F, syngeneic hind limb transplantations (BN→BN) were performed. Transplant rejection was assessed clinically and histologically.

RESULTS

Group A showed a significantly earlier onset of allograft rejection after 3.5 ± 0.2 days (p < 0.01) when compared with control groups B, C and D (5.5 ± 0.7, 5.3 ± 0.7 und 5.7 ± 0.5). Groups E and F showedno allograft rejection.

CONCLUSION

This study shows that the time of application determines the immunomodulatory effects of MICs. Whereas the systemic application of MICs on the day of transplantation led to a significant immunosuppression in previous studies, this study demonstrates that preoperative injections of MICs lead to an acceleration of allotransplant rejection. Follow-up studies are necessary to investigate further modifications of application time as well as dose-effect relations and cell characteristics of these potential immunosuppressive cells.

Pharmacokinetics and Biodistribution of Tacrolimus after Topical Administration: Implications for Vascularized Composite Allotransplantation

AIM

The high doses of oral tacrolimus (TAC) (1,2) necessary to prevent acute rejection (AR) after vascularized composite allotransplantation (VCA) are associated with systemic adverse effects. The skin is the most antigenic tissue in VCA and the primary target of AR. However, the short-term use of topical TAC (Protopic®), as an off-label adjunct to oral TAC, to treat AR episodes pro re nata (PRN), has yielded inconsistent results. There is lack of data on the pharmacokinetics and tissue distribution of topical TAC in VCA, that hampers our understanding of the reasons for unreliable efficacy. Toward this goal, we evaluated the ability of topical TAC to achieve high local tissue concentrations at the site of application with low systemic concentrations.

MATERIALS AND METHODS

We assessed the pharmacokinetics and tissue distribution of topical TAC (Protopic®, 0.03%) after single or repeated topical application in comparison to those after systemic delivery in rats. Animals received a single topical application of TAC ointment (Group 1) or an intravenous (IV) injection of TAC (Group 2) at a dose of 0.5 mg/kg. In another experiment, animals received daily topical application of TAC ointment (Group 3), or daily intraperitoneal (IP) injection of TAC (Group 4) at a dose of 0.5 mg/kg for 7 days. TAC concentrations in blood and tissues were analyzed by Liquid Chromatography-Mass Spectrometry (LC/MS-MS).

RESULTS

Following single topical administration, TAC was absorbed slowly with a Tmax of 4 h and an absolute bioavailability of 11%. The concentrations of TAC in skin and muscle were several folds higher than whole blood concentrations. Systemic levels remained subtherapeutic (< 3 ng/ml) with repeated once daily applications.

CONCLUSION

Topical application of TAC ointment (Protopic®, 0.03%) at a dose of 0.5 mg/kg/day provided high concentrations in the local tissues with low systemic exposure. Repeated topical administration of TAC is well tolerated with no local or systemic adverse effects. This study confirms the feasibility of topical application of TAC for site specific graft immunosuppression and enables future applications in VCA.

The landscape of vascularized composite allograft donation in the United States

PURPOSE OF REVIEW

Vascularized composite allograft (VCA) donation and transplantation has now demonstrated feasibility and impact to the lives of patients suffering from devastating and traumatic injury. This review summarizes the current landscape of VCA donation in the United States.

RECENT FINDINGS

VCA donations are nonlife-saving allografts, for nonlife-saving transplants - and therefore, conservative donor selection focused on the optimization of donors for the lowest risk to transplant recipients is paramount. VCA donors in the United States are a demographically and clinically diverse group that largely reflects the characteristics of the VCA candidates waiting for transplants. Public opinion about VCA donation is generally supportive, but has lower support for VCA transplants than for solid organ transplants.

SUMMARY

As an emerging area of transplantation, VCA donation is evolving in the United States with growing interest by the public, and those suffering from catastrophic injury for which reconstructive transplantation may offer excellent outcomes and a high quality of life.

Technical, Immunological, and Ethical Similarities and Differences Between Vascularized Composite Allotransplantation and Solid Organ Transplantation in Current Practice

Solid organ transplantation (SOT) is a surgical method used as the gold standard in end-term organ failure. Following SOT, successful results have also been achieved in vascularized composite tissue transplantation, which improves the quality of life with the success of solid organ transplants and the development of modern immunosuppressive regimens. This review discusses the preoperative, operative, postoperative, and immunological differences between vascularized tissue transplantation and SOT.

Characteristics and Immunomodulating Functions of Adipose-Derived and Bone Marrow-Derived Mesenchymal Stem Cells Across Defined Human Leukocyte Antigen Barriers

Background

Vascularized composite allotransplantation opens new possibilities in reconstructive transplantation such as hand or face transplants. Lifelong immunosuppression and its side-effects are the main drawbacks of this procedure. Mesenchymal stem cells (MSCs) have clinically useful immunomodulatory effects and may be able to reduce the burden of chronic immunosuppression. Herein, we assess and compare characteristics and immunomodulatory capacities of bone marrow- and adipose tissue-derived MSCs isolated from the same human individual across defined human leukocyte antigen (HLA) barriers.

Materials and methods

Samples of omental (o.) adipose tissue, subcutaneous (s.c.) adipose tissue, and bone marrow aspirate from 10 human organ donors were retrieved and MSCs isolated. Cells were characterized by flow cytometry and differentiated in three lineages: adipogenic, osteogenic, and chondrogenic. In mixed lymphocyte reactions, the ability of adipose-derived mesenchymal stem cells (ASCs) and bone marrow-derived mesenchymal stem cells (BMSCs) to suppress the immune response was assessed and compared within individual donors. HLA mismatched or mitogen stimulations were analyzed in co-culture with different MSC concentrations. Supernatants were analyzed for cytokine contents.

Results

All cell types, s.c.ASC, o.ASC, and BMSC demonstrated individual differentiation potential and cell surface markers. Immunomodulating effects were dependent on dose and cell passage. Proliferation of responder cells was most effectively suppressed by s.c.ASCs and combination with BMSC resulted in highly efficient immunomodulation. Immunomodulation was not cell contact-dependent and cells demonstrated a specific cytokine secretion.

Conclusion

When human ASCs and BMSCs are isolated from the same individual, both show effective immunomodulation across defined HLA barriers in vitro. We demonstrate a synergistic effect when cells from the same biologic system were combined. This cell contact-independent function underlines the potential of clinical systemic application of MSCs.

Chemotherapy and Transplantation: The Role of Immunosuppression in Malignancy and a Review of Antineoplastic Agents in Solid Organ Transplant Recipients

It is estimated that solid organ transplant recipients have a two- to fourfold greater overall risk of malignancy than the general population. Some of the most common malignancies after transplant include skin cancers and posttransplant lymphoproliferative disorder. In addition to known risk factors such as environmental exposures, genetics, and infection with oncogenic viruses, immunosuppression plays a large role in the development of cancer through the loss of the immunosurveillance process. The purpose of this article is to explain the role of immunosuppression in cancer and to review the classes of chemotherapeutics. The field of anticancer drugs is continually expanding and developing, with limited data on use in transplant recipients. This article aims to provide information on class review, adverse effects, dose adjustments, and drug interactions that are pertinent to the care of transplant recipients.

Hand Transplantation: Current concepts and management algorithm

Introducción. El trasplante de mano ha sido uno de los retos del siglo XXI, cuyo primer caso reportado ocurrió en 1964. En este campo se han hecho estudios y avances que permitieron explorar nuevas alternativas para el manejo del paciente con trasplante de mano, por lo que diversos centros de referencia han realizado análisis basados en sus experiencias, las cuales permitieron lograr la viabilidad de este tipo de trasplante.Objetivo. Esta revisión busca dar una visión general sobre el trasplante de mano y proponer un algoritmo de manejo.Materiales y métodos. La selección de candidatos requiere una serie de criterios, tales como evaluación clínica, paraclínica y psicosocial, desarrollados por un equipo multidisciplinario. La inmunosupresión busca evitar el rechazo y los inmunosupresores deben tener los niveles séricos apropiados para reducir sus efectos adversos. Se han reportado casos de rechazo agudo clásico y atípico, donde la piel es el principal tejido blanco, y rechazo crónico, en el cual se afectan los vasos sanguíneos. El seguimiento se realiza con varias pruebas, de modo que la de oro es la biopsia de piel.Resultados. Las complicaciones del tratamiento farmacológico derivan de la toxicidad de los medicamentos y se manifiestan como alteraciones metabólicas, infecciones oportunistas y neoplasias. La rehabilitación y los aspectos sociales, como el grado de satisfacción del paciente, deben ser evaluados durante la recuperación para asegurar adherencia al tratamiento. En 2011 el registro internacional de alotransplante compuesto de mano reportó 39 casos de trasplante de extremidades superiores con resultados variables; todo esto evidencia que para lograr un resultado óptimo y viable del trasplante debe realizarse seguimiento por un equipo multidisciplinario, red de apoyo del paciente y motivación del mismo, junto con el cumplimiento del manejo farmacológico.Conclusión. Se espera que nuevas investigaciones puedan crear estrategias para desarrollar tolerancia y, de esta forma, reducir el manejo mediante inmunosupresión.

The Macrophage-depleting Agent Clodronate Promotes Durable Hematopoietic Chimerism and Donor-specific Skin Allograft Tolerance in Mice

Hematopoietic chimerism is known to promote donor-specific organ allograft tolerance; however, clinical translation has been impeded by the requirement for toxic immunosuppression and large doses of donor bone marrow (BM) cells. Here, we investigated in mice whether durable chimerism might be enhanced by pre-treatment of the recipient with liposomal clodronate, a macrophage depleting agent, with the goal of vacating BM niches for preferential reoccupation by donor hematopoietic stem cells (HSC). We found that liposomal clodronate pretreatment of C57BL/6 mice permitted establishment of durable hematopoietic chimerism when the mice were given a low dose of donor BM cells and transient immunosuppression. Moreover, clodronate pre-treatment increased durable donor-specific BALB/c skin allograft tolerance. These results provide proof-of-principle that clodronate is effective at sparing the number of donor BM cells required to achieve durable hematopoietic chimerism and donor-specific skin allograft tolerance and justify further development of a tolerance protocol based on this principle.

Regulatory aspects of VCA in Eurotransplant

Vascularized composite allografts (VCAs) are a growing field within the area of transplantation. In 2014, the birth of a healthy baby after a successful uterus transplant from a living donor was reported in Sweden. VCAs are not specifically mentioned in any of the transplant acts of the Eurotransplant (ET) member states, which all belong to the European Union (EU). The Competent Authorities (CA) of the EU decided in 2012 that VCAs are to be regarded as organs. At the moment, there are no general guidelines in the ET area concerning wait list registration, allocation, procurement and transplantation, and also no regulations concerning reimbursement. To further develop this aspect, common policies and guidelines within the ET member states have to be developed.

Vascularized composite allotransplantation: current standards and novel approaches to prevent acute rejection and chronic allograft deterioration

The advent of more potent immunosuppressants led to the first successful human upper extremity transplantation in 1998. At this time, >100 upper extremity transplants, 30 face transplants, and a variety of other vascularized composite allotransplantation (VCA) procedures have been performed around the world. VCA recipients present unique challenges for transplantation. The incidence of acute rejection exceeds 80% in hand and face transplantation and is well documented, whereas reports about antibody-mediated rejection and chronic rejection remain scarce. Immunosuppression protocols commonly used at US centers are derived from solid organ transplantation protocols. Novel approaches to minimize rejections in VCA may include improved HLA matching and considerations toward cytomegalovirus infection status. New graft preservation techniques may decrease immunogenicity prior to transplant. Novel monitoring methods such as valid biomarkers, ultrasound biomicroscopy, and sentinel flaps may enable earlier diagnosis of rejection. Cell-based therapies are being explored to achieve immunosuppressive regimen minimization or even tolerance induction. The efficacy of local immunosuppression in clinical VCA remains controversial. In conclusion, although immunosuppressive strategies adapted from SOT have demonstrated good midterm results, focusing on the unique features of VCA grafts may enable additional, more specific treatment strategies in the future and improved long-term graft outcomes.

Procurement strategies for combined multiorgan and composite tissues for transplantation

PURPOSE OF REVIEW

The purpose of this article is to identify the unique aspects of combined multiorgan and vascularized composite allograft (VCA) procurement from deceased donors and outline the steps essential for success.

RECENT FINDINGS

Transplantation of nonsolid organ composite tissues is becoming a viable option for reconstruction of massive tissue defects. With the United Network for Organ Sharing designation of VCAs as organs, placing them under the domain of the Organ Procurement and Transplantation Network, a systematic method for combined solid organ and VCA procurement is required. Several centers have reported experience with successful procurement strategies including sequential and simultaneous retrievals. The published literature describing donor screening, sequence of procurement with relation to solid organs and allocation is reviewed.

SUMMARY

With the 2013 classification of VCAs as organs, the Organ Procurement and Transplantation Network and United Network for Organ Sharing are better suited to aligning procurement and allocation policies. As VCA transplantation becomes more commonplace, protocol guidelines will ensure smooth integration with existing procurement infrastructure.

Vascularized Composite Allografts: Procurement, Allocation, and Implementation

Vascularized composite allotransplantation is a continuously evolving area of modern transplant medicine. Recently, vascularized composite allografts (VCAs) have been formally classified as 'organs'. In this review, key aspects of VCA procurement are discussed, with a special focus on interaction with the procurement of classical solid organs. In addition, options for a matching and allocation system that ensures VCA donor organs are allocated to the best-suited recipients are looked at. Finally, the different steps needed to promote VCA transplantation in society in general and in the medical community in particular are highlighted.

Vascularized composite allotransplant in the realm of regenerative plastic surgery

Vascularized composite allotransplant (VCA) has led to new treatment options for patients with severe upper extremity and facial injuries. Although VCA can restore form and function, it exposes the patient to the risks associated with lifelong immunosuppression. Hopefully, ongoing advances in regenerative medicine will someday obviate the need for VCA, but until that time, VCA remains an immediate means of reconstructing otherwise unreconstructable defects. We review the outcomes of hand and face transplants, as well as the recent developments in immunosuppression as it relates to the field of VCA.