Vascularized composite allotransplantation (VCA) represents a transformative advance in reconstructive surgery, offering restoration of essential functions and psychological well-being for individuals with severe facial trauma or anomalies. There are different types of VCA. Facial vascularized composite allotransplantation (FVCA) is a complex procedure that carries the potential risk of severe complications in the event of rejection. There is a paucity of research that compares outcomes following FVCA to other types of VCA. Data were retrieved from the Organ Procurement and Transplantation Network (OPTN) database, which provides comprehensive information on all US organ donation and transplant activities. A search identified 96 eligible VCA cases, consisting of 16 FVCAs and 80 non-FVCA cases that were included in the final analysis. In facial vascularized composite allotransplantation (FVCA) recipients, the median number of acute rejection episodes was significantly higher compared with non-FVCA patients [5.0 (IQR=0.0-10) versus 0.0 (IQR=0.0-2.0), P=0.0022]. Similarly, the median number of hospitalizations was greater in FVCA patients [3.0 (IQR=0.75-4.0) versus 0.0 (IQR=0.0-1.0), P<0.001]. While the overall complication rates did not differ significantly between groups (44% versus 25%, P=0.14), infectious complications were notably more frequent in FVCA recipients (44% versus 15%, P=0.015). Facial vascularized composite allotransplantation (FVCA) stands out from VCA procedures due to its heightened immunologic complexity and unique clinical challenges, including high antigenicity from the included skin, presensitized patients, and visible grafts. Facial vascularized composite allotransplantation (FVCA) demands stronger immunosuppression and intensive perioperative monitoring to manage complications. Continued efforts to optimize these strategies are crucial to reduce morbidity and improve outcomes, ensuring FVCA's transformative potential is realized safely and effectively.

Chronic rejection (CR) remains a major barrier to long-term success in facial vascularized composite allotransplantation (fVCA), particularly in facial transplants. Unlike acute rejection, CR is a gradual, progressive process marked by vasculopathy, fibrosis, and functional graft decline. Histopathologic features include intimal hyperplasia, dermal sclerosis, adnexal atrophy, and telangiectasia. Immune mechanisms driving CR involve persistent activation of Th1 and Th17 T cells, macrophages, and, to a lesser extent, B cells, which form tertiary lymphoid structures. Dysregulated cytokines and chemokines, such as IFN-γ, IL-17, and IL-6, perpetuate inflammation and fibrosis, whereas the downregulation of regulatory mediators like IL-10 impairs immune resolution. Chronic antigen exposure, complement activation, and the presence of tissue-resident memory T cells further sustain graft injury. Clinically, CR presents with tightening of facial tissue, pigmentary changes, pain, and impaired oral and facial function, which can sometimes progress to necrosis and graft failure. Diagnostic challenges persist due to heterogeneous presentation and a lack of standardized criteria. Early detection through protocol biopsies, mucosal sampling, and vascular imaging is essential. Future directions emphasize the need for molecular diagnostics, targeted immunomodulation, and antifibrotic therapies. A deeper understanding of CR pathophysiology is critical to improving graft longevity and patient quality of life in fVCA.

Recently, preservation approaches such as cytoprotective agents injection, ex vivo machine perfusion, and supercooling have emerged as strategies to enhance long-term preservation of both standard and marginal organs by mitigating ischemic and hypoxic injury. Although encouraging, its application in the field of vascularized composite allotransplantation (VCA) remains largely confined to preclinical research. To date, most studies investigating VCA perfusion strategies have relied on animal models, particularly swine or rodent composites. While these models provide valuable mechanistic insights, their anatomical, immunological, and physiological differences limit reproducibility and translational relevance to human applications. In this protocol, each surgical step required for the procurement of a human deep inferior epigastric perforator (DIEP) flap for preservation studies is described in detail. The perforator is transected above the fascia without any subfascial dissection, yielding a short yet sufficient pedicle for catheterization. This model takes advantage of discarded tissue from standard abdominoplasty procedures, posing no additional risk to the patient. Critical steps are outlined to ensure a functional flap is harvested without prolonging operative time or compromising patient safety. Functional imaging is subsequently performed to confirm flap viability prior to experimental use, and sequential biopsies may be performed to follow tissue integrity. This model is particularly suited for research involving muscle-sparing VCA procedures -- such as partial facial transplantation -- and may also have relevance for the study of autologous free flap preservation.

Vascularized composite allotransplantation (VCA) has transformed reconstructive surgery for patients with severe tissue defects. Nonetheless, donor shortages remain a major limitation. Cross-sex VCA (CS-VCA) has been proposed as a means of expanding the donor pool, but concerns persist regarding potentially heightened rejection risks in sex-mismatched transplants. This review examines published adult CS-VCA cases up to May 2025. The primary outcomes analyzed were acute rejection episodes, allograft survival, immunological complications, and sequelae affecting form and function. Nine CS-VCA cases were identified (six upper extremity, one lower extremity, and two abdominal wall transplants). Eight involved female donors (median age, 47 years) and male recipients (median age, 30 years). Acute rejection occurred in five of nine cases; however, 11 of 13 allografts remained viable at follow-up (6-41 months) under immunosuppressive therapy. Two cases developed vascular complications, resulting in technical failure and partial amputation, respectively. Higher human leukocyte antigen (HLA) mismatches (mean, 5) were associated with complications, while fewer mismatches (mean, 3) correlated with better outcomes. In contrast to trends in solid organ transplantation, female-to-male CS-VCA demonstrated relatively favorable outcomes in the limited cases reported. These findings suggest that CS-VCA may be a feasible strategy to expand the VCA donor pool, provided that patient selection is careful, ABO/Rh and HLA compatibility are prioritized, and rigorous immunological monitoring is maintained. Further studies should investigate sex-specific immune mechanisms to optimize long-term success rates.

Vascularized composite allotransplantation (VCA) offers unparalleled reconstructive possibilities in complex cases but remains constrained by high immunogenicity and marked susceptibility to ischemia-reperfusion injury (IRI), particularly in muscle-rich grafts. Static cold storage (SCS), the current clinical standard, preserves grafts only for short durations. In contrast, machine perfusion (MP), already transformative in solid organ transplantation, is emerging as a promising strategy for VCA. This review summarizes the main challenges of exvivo VCA preservation and current perfusion strategies designed to overcome them. Particular attention is given to physiological and technical factors influencing graft integrity, as well as innovations in perfusate composition and protective additives that mitigate IRI and support tissue preservation. Beyond simple storage, MP platforms enable functional assessment and therapeutic interventions, including graft reconditioning and immune modulation prior to transplantation. Complementary subzero static preservation methods, such as supercooling and cryopreservation, also show promise for substantially extending preservation times. Together with advances in experimental models, these approaches are reshaping the preservation landscape. As the field evolves, MP is poised to become a cornerstone technology in VCA, improving graft quality, extending preservation duration, and enabling pre-implantation modification strategies to reduce rejection and enhance long-term outcomes.

The very first human Whole Eye Transplant (WET) has sparked new hope for patients who have lost vision due to major ophthalmic injury, but significant challenges remain to be addressed before vision restoration through WET can become achievable. Among these, one of the most critical challenges is ex vivo preservation. The eyeball, particularly its neural components such as the retina and optic nerve, undergoes rapid and irreversible degeneration within minutes unless proper preservation is ensured. Static cold storage (SCS) remains the gold standard in vascularized composite allotransplantation (VCA) but is not suited to WET ex vivo preservation due to its inability to sufficiently suppress or support metabolism, leading to loss of graft viability and function. Subnormothermic machine perfusion (SNMP) has emerged as a promising alternative to SCS, offering the potential not only to preserve grafts but also to recondition them. Our group has successfully translated SNMP from solid organ transplantation to several VCA models, demonstrating its feasibility and advantages. Herein, we report the application of SNMP to preserve a WET in swine, detailing the anatomical model and preservation protocol. This approach represents a significant step forward in optimizing WET preservation and transplantation techniques.

Ex vivo perfusion recellularization of acellular rat hindlimbs for vascular composite allotransplantation

Vascularized composite allotransplantation (VCA) restores complex tissue defects but demands lifelong systemic immunosuppression. Oral tacrolimus (TAC) is limited by a narrow therapeutic window, pharmacokinetic variability, adherence challenges, and toxicity. Local delivery could mitigate these issues, yet clinical translation has been hindered by burst release, short duration, and the inability to co-deliver agents.We developed PRECISE (Programmable, REtrievable, Controlled ImmunoSuppression Encapsulator), an injectable, in-situ–forming PLGA depot that achieves long-acting, tightly controlled TAC release via structure-guided co-formulation with drug-binding agents (DBAs). GRAS small molecules (e.g., EGCG, maltotriose) identified by in silico docking and in vitro screening suppressed burst and modulated solvent efflux. Notably, rapamycin (RAPA) served dually as an mTOR inhibitor and a TAC-binding excipient, enabling synchronized dual-agent delivery.PRECISE eliminated burst in vitro and produced coordinated TAC+RAPA release with clinically compatible injectability. In rats, monthly intragraft dosing maintained systemic TAC/RAPA within the therapeutic window (~5–10 ng/mL) for >300 days, prolonged hindlimb allograft survival, expanded Tregs, and induced donor-specific hyporesponsiveness. Surgical retrieval of the depot triggered rapid TAC decline, demonstrating reversibility. In a stringent, fully MHC-mismatched porcine VCA model, PRECISE maintained on-target drug levels and extended graft survival beyond 90 days with minimal rejection and preserved vascular integrity.PRECISE is, to our knowledge, the first retrievable, injectable platform to deliver long-acting, dual-agent immunosuppression with controlled kinetics, rapid attainment of therapeutic steady state, and sustained graft protection. Its modular, structure-guided design enables clinical translation across VCA and solid-organ transplantation, delivering precise, durable, and safer immunosuppression.

A challenge in vascularized composite allotransplantation (VCA) is mitigating tissue damage within the composite secondary to brain death (BD). Loss of central nervous system function disrupts S-nitrosothiol (SNO) homeostasis to produce systemic hypoxia and ischemic injury during the donor support phase. We reasoned that addition of an S-nitrosylating agent to the preservation solution could correct this damage during ex vivo storage. Employing a swine BD preparation, we excised VC tissues (abdominal blocks and limbs) after a 16-h period of systemic support. The composites were perfused with/without the S-nitrosylating agent ethyl nitrite (ENO) present in the preservation solution. Flow rates and resistance were recorded during the storage period; tissue hypoxia was also quantified. BD decreased circulating SNO levels and reduced tissue oxygenation and muscle protein NO content. During storage, ENO increased flow and decreased resistance within the VCs. Muscle from ENO-treated VCs had lower protein levels of inducible nitric oxide synthase and the hypoxia marker Hif1α and higher levels of the anti-apoptotic protein Bcl2, all suggestive of enhancements of tissue oxygenation. As such, ex vivo S-nitrosylation therapy may be a means to correct BD-induced impairments in SNO-status to improve the quality of composite tissue grafts prior to transplantation.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-21591-5.

Understanding Human Leukocyte Antigens in Vascularized Composite Allotransplantation.

Analyzing the candidate pool for Vascularized Composite Allotransplantation - A multi-center OPTN study with a focus on face transplant candidates.

The Current Status of Vascularized Composite Allotransplantation: From Experimental Frontier to Reconstructive Reality.

Background.Subnormothermic machine perfusion shows promise as a viable alternative to static cold storage for prolonged preservation of vascularized composite allografts. To date, most studies have been conducted in nonprimate models, and we report its first utilization in a cynomolgus forearm preclinical model for 24-h preservation.Methods.Forearms were procured from nonhuman primates weighing between 5 and 8 kg. Two perfusion protocols were implemented. In group 1 (n = 6), limbs were perfused with 1.5 L of recirculating Steen; the perfusate flow was adjusted to maintain stable vascular pressures. In group 2 (n = 6), limbs were perfused with a Steen+ solution, doubling the albumin concentration, with a full-volume exchange at mid-perfusion under a stable low-flow regimen. Dynamic and metabolic parameters, histological analysis, and response to neurostimulation were assessed.Results.After 24 h of continuous perfusion, mean weight gain was 24.8 ± 5.5% in group 1 and 8.0 ± 4.7% in group 2. Perfusion and metabolic parameters indicated the onset of a compartment syndrome in group 1 with an increase in resistance, lactate, and potassium production at mid-perfusion. In group 2, dynamic and metabolic parameters remained stable for 24 h, and histological analysis showed well-preserved tissues. Finally, in group 2, limbs exhibited muscular contraction recovery quantified at 2.4/5 ± 0.89 after 24 h compared with 0/5 after 3 h of ischemia or after perfusion in group 1.Conclusions.Successful 24-h perfusion and muscle contractility restoration demonstrate promising outcomes for vascularized composite allograft preservation and reconditioning.

Vascularized composite allotransplantation (VCA) represents one of the most complex frontiers in reconstructive surgery, requiring simultaneous transfer of multiple tissue types, including skin, muscle, bone, and nerves. Success depends on the multidisciplinary integration of immunology, surgery, rehabilitation, and psychology. Chang Gung Memorial Hospital has established itself as a pioneer in clinical VCA in Taiwan, contributing significantly through innovative basic research and successful clinical outcomes. This review explores our institutional experience, highlighting clinical cases and groundbreaking preclinical research within our comprehensive VCA program.

Vascularized composite allotransplantation (VCA) is a potential treatment for extensive injuries that replaces defects like-with-like, however allografts are immune-rejectable. This study developed in vitro thymic organoids and examined whether donor-derived HSCs could be educated in vivo into T lymphocytes via central tolerance. TECs, TMCs, and HSCs from C57BL/7 (CD45.2+) or SJL/L (CD45.1+) mice were labeled with cell surface markers and examined by flow cytometry. Co-culturing three cell lines in vitro created thymic aggregates. Aggregates transplanted to C57BL/7 (CD45.2+) mice's inguinal regions developed thymic organoids. Immunorejection genes were identified bioinformatically. Western blot, immunofluorescence, and flow cytometry were utilized to measure rejection-related protein levels and T cell surface markers in thymic organoids to determine T cell inducement and immunomodulation. In vitro, TECs, TMCs, and HSCs created thymic aggregates, which became thymic organoids after in vivo transplantation and produced CD8+ and CD4+ Tregs. Bioinformatics showed high correlations between transplanted rejection and IFNG, IL2RG, FCGR3A, and ICAM1 genes. Immunofluorescence and Western blot showed increased protein expression of IFNG, IL2RG, FCGR3A (immunomodulation biomarker), and decreased protein expression of CK8, CK14, and ICAM1 (TEC biomarker) in thymic organoids. Thymic organoids heterotopically implanted in vivo can promote heterologous HSC-derived T cell development.

Characterizing Donor- and Recipient-Derived Macrophages in Vascularized Composite Allotransplantation Rejection

Vascularized composite allotransplantation (VCA), including hand transplantation, provides a unique opportunity to overcome the defective functions of traumatic transamputees and fill the gaps of congenital limb deficiencies. From 2015 to 2025, advancements in hand transplantation techniques have been evaluated in reviews synthesizing functional outcomes: motor recovery (DASH scores averaging 20–30 points), sensory recovery (s-2PD &lt;10 mm in 70% of recipients after two years), and psychosocial improvements (e.g., higher SF-36 scores). Microsurgical improvement, achieved through precise nerve coaptation and the minimization of immunosuppression with alemtuzumab and thymoglobulin, has led to more than 150 transplants since 1998, with rejection rates limited to 27.9 per cent. Innovations in the drug rehabilitation process, such as biofeedback and virtual reality, enhance the process of cortical reintegration. Advancements in bioengineering, including the use of decellularised nerve allografts and mesenchymal stem cells, offer a method for regenerating nerve tissue and reducing the need for immunosuppression. Difficulties continue to persist, such as graft loss (10.8%), chronic rejection and complications caused by immunosuppression (e.g. renal dysfunction, infections). Discrimination in access around the world has become another priority; however, ethical issues, including fair patient selection and informed consent, continue to be of concern. This systematic review highlights the need to create standard outcome measures and international registries to streamline clinical practices. With the removal of immunological, ethical, and accessibility barriers, hand transplantation will become a reality that improves outcomes for patients worldwide.

Vascularized composite allotransplantation (VCA) has emerged as a novel therapy approach to restore form and function in patients with severe tissue defects of the face, hand, and abdominal wall, among other anatomical regions. The composite allografts comprise different tissues such as skin, muscle, or bone. Clinical data demonstrate promising mid- and long-term outcomes following VCA surgery, but our understanding of the cellular interactions and molecular pathways in VCA surgery is oftentimes deduced from solid organ transplantation (SOT). In SOT, the concept of cellular senescence has grown increasingly popular which is characterized by a permanent cellular proliferation arrest in response to endogenous and exogenous stimuli. Senescent cells, through the release of mitochondrial DNA and secretion of proinflammatory proteins, can amplify the immunogenicity of transplants, hindering graft acceptance and longevity. This understanding has paved the way for novel interventions, including the use of senolytics-agents that selectively eliminate senescent cells-to modulate immune responses and mediate immunotolerance. There is a body of evidence that underlines the therapeutic potential of senescence to improve SOT outcomes; however, the relevance of senescence to VCA outcomes remains elusive. In this review, we aim to summarize the current literature on senescence in different solid organ transplants and outline the potential impact of senescence on VCA outcomes. This knowledge may help providers develop a broader understanding of the cellular and molecular landscape in VCA to develop targeted therapies and advance VCA patient care.

Vascularized composite allotransplantation (VCA) involves the transplantation of multiple tissue types -- including skin, muscle, bone, and nerves -- offering a promising reconstructive option for patients with severe traumatic injuries or disfigurements. Despite its transformative potential, VCA has encountered significant challenges such as graft rejection, chronic immunosuppression complications, and neuromuscular recovery's intricacies. We utilize a rat forelimb model as a cost-effective and anatomically relevant platform to address these challenges. The rat forelimb closely mirrors human limb anatomy, enhancing our findings' translational impact. Previous studies have validated this model for reliably and reproducibly measuring functional recovery, thereby establishing it as a key tool for assessing the rejection trajectory of forelimb grafts. Moreover, the model offers a valuable opportunity to explore innovative therapeutic approaches and serve as a good translational platform for novel preservation techniques. Through further investigation of this model, we aim to deepen our understanding of the mechanisms behind graft rejection and neuromuscular recovery. Ultimately, this work strives to pave the way for improving clinical outcomes of VCA, addressing both current limitations and future challenges in transplant medicine.

Extensive and complex abdominal wall defects, particularly those associated with intestinal or visceral organ damage, pose significant medical and surgical challenges. An ideal reconstruction must restore anatomy, function, sensation, and body image. Currently, no conventional reconstruction method fulfills all these criteria in such complex scenarios. However, vascularized composite allotransplantation (VCA) offers a unique solution, providing satisfactory anatomical and functional outcomes -- albeit at the cost of lifelong immunosuppression. Since the first reported human case in 2003, approximately 40 abdominal wall transplants have been performed worldwide, all in conjunction with intestinal or multivisceral transplantation. While various technical adaptations have been described, the procedure has proven to be both safe and effective for patients with complex abdominal wall defects. To date, no reinnervated abdominal wall allograft has been attempted in humans. However, reinnervation appears to be the next frontier, with the potential to enhance functional outcomes and reduce complications. This protocol outlines a standardized procedure for harvesting and preparing a vascularized abdominal wall composite allograft, designed to ensure optimal results and minimize tissue damage. The graft, vascularized via the deep inferior epigastric vessels, is harvested with generous margins to enable tension-free reconstruction. We also detail the specific steps required to collect an innervated specimen. At the end of the procedure, the two deep inferior epigastric arteries are cannulated, and the graft is perfused with preservation solution for transport. Ultimately, this protocol aims to standardize abdominal wall graft procurement. It is intended as a valuable resource for both translational research and clinical applications, particularly as interest in abdominal wall transplantation continues to grow.