Current Opinion in Organ Transplantation最新文献

Purpose of review: In an attempt to reduce waiting list mortality in liver transplantation, less-than-ideal quality donor livers from extended criteria donors are increasingly accepted. Predicting the outcome of these organs remains a challenge. Machine perfusion provides the unique possibility to assess donor liver viability pretransplantation and predict postreperfusion organ function.

Recent findings: Assessing liver viability during hypothermic machine perfusion remains challenging, as the liver is not metabolically active. Nevertheless, the levels of flavin mononucleotide, transaminases, lactate dehydrogenase, glucose and pH in the perfusate have proven to be predictors of liver viability. During normothermic machine perfusion, the liver is metabolically active and in addition to the perfusate levels of pH, transaminases, glucose and lactate, the production of bile is a crucial criterion for hepatocyte viability. Cholangiocyte viability can be determined by analyzing bile composition. The differences between perfusate and bile levels of pH, bicarbonate and glucose are good predictors of freedom from ischemic cholangiopathy.

Summary: Although consensus is lacking regarding precise cut-off values during machine perfusion, there is general consensus on the importance of evaluating both hepatocyte and cholangiocyte compartments. The challenge is to reach consensus for increased organ utilization, while at the same time pushing the boundaries by expanding the possibilities for viability testing.

Purpose of review: The aim of the current review is to highlight the importance of exercise training as an important section of transplant recipient rehabilitation process and explain the role of the exercise scientist in the development, implementation, and assessment of the exercise regime.

Recent findings: Transplant patients face a unique set of challenges in their recovery and rehabilitation process, often requiring a multifaceted approach to address the physical, emotional, and psychological aspects of their condition. Exercise training has emerged as a crucial component in the care of these patients, providing a means to improve functional capacity, enhance quality of life, and mitigate the adverse effects of transplant-related complications. Exercise scientists who are trained to assess patient's physical limitations, develop and deliver personalized exercise programs, and monitor their progress are uniquely positioned to play a crucial role in the treatment of patients with chronic conditions that require exercise training as a mean of improving and maintaining health and quality of life.

Summary: Exercise scientists are the appropriate professionals for providing transplant recipients with the recommended exercise training for maintaining and improving their health status as part of the overall plan of long-term care and support.

Purpose of review: Normothermic regional perfusion (NRP) is a novel procurement technique for donation after circulatory death (DCD) in the United States. It was pioneered by cardiothoracic surgery programs and is now being applied to abdominal-only organ donors by abdominal transplant programs.

Recent findings: Liver and kidney transplantation from thoracoabdominal NRP (TA-NRP) donors in the United States was found to have lower rates of delayed kidney graft function and similar graft and patient survival versus recipients of cardiac super rapid recovery (SRR) DCD donors. The excellent outcomes with NRP have prompted the expansion of NRP technology to abdominal transplant programs.

Summary: Excellent early outcomes with liver and kidney transplantation have prompted the growth of NC-NRP procurement for abdominal-only DCD donors across the US, and now requires standardization of technical and nontechnical aspects of this procedure.

Purpose of review: In recent years, the xenotransplantation science has advanced tremendously, with significant strides in both preclinical and clinical research. This review intends to describe the latest cutting-edge progress in knowledge and methodologies developed to overcome potential obstacles that may preclude the translation and successful application of clinical xenotransplantation.

Recent findings: Preclinical studies have demonstrated that it is now possible to extend beyond two years survival of primate recipients of life saving xenografts. This has been accomplished thanks to the utilization of genetic engineering methodologies that have allowed the generation of specifically designed gene-edited pigs, a careful donor and recipient selection, and appropriate immunosuppressive strategies.In this light, the compassionate use of genetically modified pig hearts has been authorized in two human recipients and xenotransplants have also been achieved in human decedents. Although encouraging the preliminary results suggest that several challenges have yet to be fully addressed for a successful clinical translation of xenotransplantation. These challenges include immunologic, physiologic and biosafety aspects.

Summary: Recent progress has paved the way for the initial compassionate use of pig organs in humans and sets the scene for a wider application of clinical xenotransplantation.

Purpose of review: The adoption of brain death played a crucial role in the development of organ transplantation, but the concept has become increasingly controversial. This essay will explore the current state of the controversy and its implications for the field.

Recent developments: The brain death debate, long limited to the bioethics community, has in recent years burst into the public consciousness following several high-profile cases. This has culminated in the reevaluation of the Uniform Determination of Death Act (UDDA), which is in the process of being updated. Any change to the UDDA has the potential to significantly impact the availability of organs.

Summary: The current update to the UDDA introduces an element of uncertainty, one the brain death debate had not previously had.

Purpose of review: The number of patients on the liver transplant waitlist continues to grow and far exceeds the number of livers available for transplantation. Normothermic machine perfusion (NMP) allows for ex-vivo perfusion under physiologic conditions with the potential to significantly increase organ yield and expand the donor pool.

Recent findings: Several studies have found increased utilization of donation after cardiac death and extended criteria brain-dead donor livers with implementation of NMP, largely due to the ability to perform viability testing during machine perfusion. Recently, proposed viability criteria include lactate clearance, maintenance of perfusate pH more than 7.2, ALT less than 6000 u/l, evidence of glucose metabolism and bile production. Optimization of liver grafts during NMP is an active area of research and includes interventions for defatting steatotic livers, preventing ischemic cholangiopathy and rejection, and minimizing ischemia reperfusion injury.

Summary: NMP has resulted in increased organ utilization from marginal donors with acceptable outcomes. The added flexibility of prolonged organ storage times has the potential to improve time constraints and transplant logistics. Further research to determine ideal viability criteria and investigate ways to optimize marginal and otherwise nontransplantable liver grafts during NMP is warranted.

Purpose of review: Normothermic regional perfusion (NRP) is a novel procurement technique for donation after circulatory death (DCD) in the United States. It was pioneered by cardiothoracic surgery programs and is now being applied to abdominal-only organ donors by abdominal transplant programs. Multiple technical approaches can be used for abdominal-only NRP DCD donors and this review describes these techniques.

Recent findings: NRP has been associated with higher utilization of organs, particularly liver and heart grafts, from DCD donors and with better recipient outcomes. There are lower rates of delayed graft function in kidney transplant recipients and lower rates of ischemic cholangiopathy in liver transplant recipients. These benefits are driving increased interest from abdominal transplant programs in using NRP for DCD procurements.

Summary: This paper describes the technical aspects of NRP DCD that allow for maximization of its use based on different donor and policy characteristics.

Purpose of review: While liver transplant for unresectable colorectal cancer liver metastases (CRLM) has been demonstrated to be a promising treatment in selected patients, the typically low MELD score of these patients and lack of exception points may lead to challenges in receiving a deceased donor liver for transplant.

Recent findings: Several studies have shown improved outcomes in select patients with CRLM who undergo liver transplant, and several trials are ongoing and will conclude in the next several years. MELD exception points have recently been proposed in qualifying patients with CRLM to help this group obtain more timely quality allografts. Under the current proposal, patients with CRLM would receive a score of the median MELD at transplant (MMaT) for their center minus 20 with a minimum score of 15 in cases where MMaT minus 20 would be less than 15. This would allow them to receive transplants faster without competing unnecessarily with those with greater medical need.

Summary: Giving MELD exception points to patients with colorectal cancer liver metastases in need of transplant may decrease time on the waitlist and improve outcomes for these patients.