Current Opinion in Organ Transplantation最新文献

Purpose of review: As one of the early hand transplant programs in the world, we are often asked to educate other programs on the lessons we have learned and on how to set up a successful hand transplantation program.

Recent findings: Two decades of global experience with vascularized composite allotransplantation (VCA) of the upper limb have demonstrated improved functional outcomes and quality of life for carefully screened patients. Despite initial reticence about VCA, over 30 patients in the USA have benefited from hand transplantation, with around 80% long-term successes. We have experience with four bilateral upper extremity patients who have undergone bilateral upper extremity allotransplants. This review article highlights our personal experience and lessons with respect to VCA team assembly, logistics, patient selection, perioperative planning, the operative procedure, and postoperative management.

Summary: Continual learning and critical evaluation are crucial to maintaining a successful upper extremity VCA program. This will ensure that patients who stand to benefit most from this life-enhancing procedure are identified and are others optimized to achieve the best possible outcomes.

Purpose of review: Despite significant advancements in the field of vascularized composite allotransplantation, challenges, particularly regarding the long-term viability and functionality of vascularized composite allotransplantation (VCA) grafts, persist. This paper provides a review of the current literature on the longevity of VCA grafts, focusing on factors influencing graft survival, immunological considerations and clinical outcomes.

Recent findings: Longevity of VCA grafts is influenced by a variety of peri- and postoperative factors including cold ischemia time, human leukocyte antigen matching, environmental exposure, psychosocial factors, adherence, immunosuppression, and complications. Due to the limited number of VCA transplants performed and heterogenous reporting, direct correlation of single factors with VCA outcomes remains inconclusive. Indirect evidence, however, supports their importance. High immunosuppressive burden, frequent occurrence of acute and accumulating cases of chronic rejection remain a significant challenge of the field.

Summary: Insights gained from this review aim to inform clinical practice and guide future research endeavors with the goal of ameliorating outcomes after VCA transplantation and facilitate wider use of VCA grafts for restoration of tissue defects.

Purpose of review: The purpose of this review is to explore the lessons learned from experimental and human tracheal transplantation to determine if this information may be applied to lung transplantation.

Recent findings: Experimental work in animal models and the recent human tracheal transplantation suggests that a robust tracheal vascular supply prevents anastomotic complications. Further, this work demonstrates that tracheal allografts undergo a progressive chimerism as recipient epithelium repopulates the allograft. In contrast to most vascularized composite allografts such as hand and face transplantation that experience high rates of rejection, the tracheal allograft did not demonstrate rejection. This may suggest that tissue chimerism plays a role in evading immune-mediated allograft rejection.

Summary: While anastomotic complications and chronic allograft rejection are the most common complications related to lung transplantation, the findings associated with tracheal transplantation may have implications for both reducing complications associated with lung transplantation.

Purpose of review: Significant advancements have been made in the field of vascularized composite allotransplantation (VCA); however, like solid organ transplantation, bypassing the recipient's immune response remains a significant obstacle to long-term allograft survival. Therefore, strategies to overcome acute and chronic rejection and minimize immunosuppressive therapy are crucial for the future of VCA. This review highlights recent attempts to induce tolerance in VCA and discusses key findings through a clinical lens.

Recent findings: Promising VCA tolerance protocols are being investigated, with five recent studies illustrating various successes. These preclinical approaches demonstrate a correlation between the presence of donor-derived T cells and VCA tolerance, the importance of using clinically available reagents within preclinical protocols, and the ability to induce sustained tolerance through nonmyeloablative methods. Furthermore, environmental factors, such as NB-UVB light are being investigated for their immunomodulation properties and may influence VCA graft rejection.

Summary: To widen the scope of VCA, minimization of immunosuppression is needed. Overall, tolerance induction protocols should have a low-toxicity level, minimally invasive induction therapies, and utilize short-term immunosuppressive medications. By examining the milestones of recent studies, researchers can gain new technical approaches to immune modulation and make data-driven amendments to tolerance protocols in preparation for clinical translation.

Purpose of review: Allograft vasculopathy in vascularized composite allografts (VCA) remains understudied. This review explores the vascular changes in VCA, focused on recent literature.

Recent findings: Allograft vasculopathy in VCA generally includes progressive concentric myointimal thickening and luminal narrowing of arterial vessels through endothelial deterioration and proliferation of smooth muscle cells. Microvascular changes are also noted, with thrombosis and lumen narrowing in microvessels of the skin even in the absence of large vessel vasculopathy. Histopathologic reports of skin containing VCA rejection document arteriosclerosis in deep vessels that are not always reflected in skin punch biopsies. The first revision of the Banff VCA scoring system 2022 was developed to include vascular changes in VCA. The scoring system for chronic changes and antibody mediated rejection continues to be under development.

Summary: The study of vascular changes in VCA continues to progress. Important data and advances in experimental and clinical VCA have been reported and continue to take place. Challenges ahead include capture of clinical data that will evolve beyond transient report forms and approaching on the problem of graft failure well grounded in sound scientific methodology.

Purpose of review: While multidisciplinary collaboration is a tenant of quality heart failure care and critical to the success of transplant programs, this essay challenges the temptation to shoehorn adult congenital heart disease (ACHD) patients into preexisting processes and paradigms. We explore the development of more relevant models, purposefully designed to improve ACHD transplant volumes and outcomes.

Recent findings: Globally, the rapid acceleration of ACHD patients living with and dying from HF stands in stark contrast to their access to transplant. Inferior early outcomes after ACHD transplant remain an undeniable barrier. And yet while all large registry datasets attest to this statistic, a few centers have achieved results comparable to those in acquired heart disease. This despite increases in both ACHD candidate complexity and referrals for Fontan Circulatory Failure. Perhaps something in their approach to care delivery is key?.

Summary: Alone, neither ACHD nor transplant programs can provide optimal management of HF in ACHD. A siloed approach is similarly inadequate. Building new ACHD-HF-Transplant teams, centered on the patient and supplemented by ad hoc expert partnerships, is an exciting approach that can improve outcomes, create a high-quality training environment, and in our experience, is a truly rewarding way of working together.

Purpose of review: With advances in the field of congenital cardiac surgery and in the management of congenital heart defects in early life, the population of adult congenital heart disease (ACHD) patients is increasing. End-stage heart failure is currently the main cause of cardiovascular mortality and is expected to increase in the coming years. This review summarizes recent innovations in transplant techniques, with special attention to what is known in the population of ACHD recipients.

Recent findings: The use of machine perfusion for heart preservation enables longer preservation times. Normothermic (organ care system - OCS) and hypothermic (hypothermic oxygenated perfusion - HOPE) machine perfusion will alleviate the time pressure associated with heart transplantation in the ACHD population, may allow for expansion of the geographical range in which donors can be matched and may improve graft quality. Donation after circulatory death (DCD) heart transplantation, either through direct procurement-machine perfusion (DP-MP) or thoraco-abdominal normothermic regional perfusion (TA-NRP) is a viable strategy to further expand the donor pool.

Summary: The use of machine perfusion and DCD donors in ACHD is feasible and shows promise. Time pressure and shortage of donors is even more critical in ACHD than in other patient populations, making these innovations particularly relevant. Further clinical experience and research is needed to elucidate their impact.

Purpose of review: Prehabilitation, defined as preparing the body physically and psychologically for upcoming surgery is of increasing prominence in presurgical care. The aim of this review is to discuss the evidence base around prehabilitation in solid organ transplantation, the use of digital health as a tool to deliver these interventions, and consider future directions.

Recent findings: Prehabilitation is of increasing interest as an adjunct to pretransplant care for individuals working up for solid organ transplantation. To date, research has shown that prehabilitation is acceptable and feasible; however, the literature base remains small. The majority of research has been delivered using in-person rehabilitation programmes, and the evidence base utilizing digital health as a means to deliver prehabilitation is limited.

Summary: To date, the research evidence base in prehabilitation for solid organ transplantation is limited. Evidence in other surgical populations has demonstrated promising results, particularly in aerobic capacity, physical function and postoperative complications. Further high-quality randomized controlled clinical trials are required to strengthen the evidence base, understand how digital health can be harnessed and utilized to deliver multimodal prehabilitation with an aim to see how this may form part of routine care in the solid organ transplantation pathway.