Resumo em Inglês:

This special issue is dedicated to the common challenge topics in pediatric transplantation. It contains 11 chapters, ranging from clinical research in pediatric transplantation to translational research (from bench to bedside). It includes comprehensive reviews from renowned scientists, clinicians and surgeons from five countries from the International Pediatric Transplantation Association (IPTA), Harvard University, the University of Miami and the University of São Paulo Medical School. The clinical management of specific issues, such as sensitized patients and ABO blood type-incompatible transplantation, is addressed. In addition, the challenges facing this patient population and the future perspectives for clinical research are discussed.

Resumo em Inglês:

One of the ultimate goals of successful solid organ transplantation in pediatric recipients is attaining an optimal final adult height. This manuscript will discuss growth following transplantation in pediatric recipients of kidney, liver, heart, lung or small bowel transplants. Remarkably similar factors impact growth in all of these recipients. Age is a primary factor, with younger recipients exhibiting the greatest immediate catch-up growth. Graft function is a significant contributing factor, with a reduced glomerular filtration rate correlating with poor growth in kidney recipients and the need for re-transplantation with impaired growth in liver recipients. The known adverse impact of steroids on growth has led to modification of the steroid dose and even steroid withdrawal and avoidance. In kidney and liver recipients, this strategy has been associated with the development of acute rejection. In infant heart transplantation, avoiding maintenance corticosteroid immunosuppression is associated with normal growth velocity in the majority of patients. With marked improvements in patient and graft survival rates in pediatric organ recipients, quality of life issues, such as normal adult height, should now receive paramount attention. In general, normal growth following solid organ transplantation should be an achievable goal that results in normal adult height.

Resumo em Inglês:

Immunosuppressive therapy in pediatrics continues to evolve. Over the past decade, newer immunosuppressive agents have been introduced into adult and pediatric transplant patients with the goal of improving patient and allograft survival. Unfortunately, large-scale randomized clinical trials are not commonly performed in children. The purpose of this review is to discuss the newer immunosuppressive agents available for induction therapy, maintenance immunosuppression, and the treatment of rejection.

Resumo em Inglês:

The sensitization of patients to human leukocyte antigens prior to heart transplantation is increasingly being recognized as an important challenge both before and after the transplant, and the effects of sensitization on clinical outcomes are just beginning to be understood. Many patients are listed with the requirement of a negative prospective or virtual crossmatch prior to accepting a donor organ. This strategy has been associated with both longer waitlist times and higher waitlist mortality. An alternative approach is to transplant across a potentially positive crossmatch while utilizing strategies to decrease the significance of the human leukocyte antigen antibodies. This review will examine the challenges and the impact of sensitization on pediatric patients prior to and following heart transplantation.

Resumo em Inglês:

The Japanese ABO-Incompatible Transplantation Committee officially collected and analyzed data on pediatric ABO-incompatible living-donor kidney transplantation in July 2012. The age of a child was defined as <16 years, and 89 children who had undergone ABO-incompatible living-donor kidney transplantation from 1989 to 2011 were entered in a registry. These data were presented as the Japanese registry of pediatric ABO-incompatible living-donor kidney transplantation at the regional meetings of the International Pediatric Transplantation Association (IPTA) in Nagoya in September 2012 and in Sao Paulo in November 2012.

Resumo em Inglês:

Solid organ transplantation has transformed the lives of many children and adults by providing treatment for patients with organ failure who would have otherwise succumbed to their disease. The first successful transplant in 1954 was a kidney transplant between identical twins, which circumvented the problem of rejection from MHC incompatibility. Further progress in solid organ transplantation was enabled by the discovery of immunosuppressive agents such as corticosteroids and azathioprine in the 1950s and ciclosporin in 1970. Today, solid organ transplantation is a conventional treatment with improved patient and allograft survival rates. However, the challenge that lies ahead is to extend allograft survival time while simultaneously reducing the side effects of immunosuppression. This is particularly important for children who have irreversible organ failure and may require multiple transplants. Pediatric transplant teams also need to improve patient quality of life at a time of physical, emotional and psychosocial development. This review will elaborate on the long-term outcomes of children after kidney, liver, heart, lung and intestinal transplantation. As mortality rates after transplantation have declined, there has emerged an increased focus on reducing longer-term morbidity with improved outcomes in optimizing cardiovascular risk, renal impairment, growth and quality of life. Data were obtained from a review of the literature and particularly from national registries and databases such as the North American Pediatric Renal Trials and Collaborative Studies for the kidney, SPLIT for liver, International Society for Heart and Lung Transplantation and UNOS for intestinal transplantation.

Resumo em Inglês:

The number of pediatric kidney transplants has been increasing in many centers worldwide, as the procedure provides long-lasting and favorable outcomes; however, few papers have addressed the immediate postoperative care of this unique population. Herein, we describe the management of these patients in the early postoperative phase. After the surgical procedure, children should ideally be managed in a pediatric intensive care unit, and special attention should be given to fluid balance, electrolyte disturbances and blood pressure control. Antibiotic and antiviral prophylaxes are usually performed and are based on the recipient and donor characteristics. Thrombotic prophylaxis is recommended for children at high risk for thrombosis, although consensus on the optimum therapy is lacking. Image exams are essential for good graft control, and Doppler ultrasound must be routinely performed on the first operative day and promptly repeated if there is any suspicion of kidney dysfunction. Abdominal drains can be helpful for surveillance in patients with increased risk of surgical complications, such as urinary fistula or bleeding, but are not routinely required. The immunosuppressive regimen starts before or at the time of kidney transplantation and is usually based on induction with monoclonal or polyclonal antibodies, depending on the immunological risk, and maintenance with a calcineurin inhibitor (tacrolimus or ciclosporin), an anti-proliferative agent (mycophenolate or azathioprine) and steroids.

Resumo em Inglês:

In the last 25 years, liver transplantation in children has become an effective, definitive, and universally accepted treatment for terminal liver diseases. Long-term survival exceeds 80% and improves each year as the result of constant technical advancements and improvements in immediate postoperative intensive care and clinical control.

Resumo em Inglês:

Heart transplantation is an option for children with complex congenital heart disease and cardiomyopathies. A patient's quality of life and long-term survival depend on successful management of the surgical complications and adverse side effects of immunosuppression. The purpose of this review was to summarize the practical management of postoperative care in this patient population and to make recommendations for the future.

Resumo em Inglês:

Lung transplantation is a well-established treatment for advanced lung diseases. In children, the diseases that most commonly lead to the need for a transplantation are cystic fibrosis, pulmonary hypertension, and bronchiolitis. However, the number of pediatric lung transplantations being performed is low compared with the number of transplants performed in the adult age group. The objective of this study was to demonstrate our experience with pediatric lung transplants over a 10-year period in a program initially designed for adults.

Resumo em Inglês:

In this review, we identify important challenges facing physicians responsible for renal and cardiac transplantation in children based on a review of the contemporary medical literature. Regarding pediatric renal transplantation, we discuss the challenge of antibody-mediated rejection, focusing on both acute and chronic antibody-mediated rejection. We review new diagnostic approaches to antibody-mediated rejection, such as panel-reactive antibodies, donor-specific cross-matching, antibody assays, risk assessment and diagnosis of antibody-mediated rejection, the pathology of antibody-mediated rejection, the issue of ABO incompatibility in renal transplantation, new therapies for antibody-mediated rejection, inhibiting of residual antibodies, the suppression or depletion of B-cells, genetic approaches to treating acute antibody-mediated rejection, and identifying future translational research directions in kidney transplantation in children. Regarding pediatric cardiac transplantation, we discuss the mechanisms of cardiac transplant rejection, including the role of endomyocardial biopsy in detecting graft rejection and the role of biomarkers in detecting cardiac graft rejection, including biomarkers of inflammation, cardiomyocyte injury, or stress. We review cardiac allograft vasculopathy. We also address the role of genetic analyses, including genome-wide association studies, gene expression profiling using entities such as AlloMap®, and adenosine triphosphate release as a measure of immune function using the Cylex® ImmuKnow™ cell function assay. Finally, we identify future translational research directions in heart transplantation in children.

Resumo em Inglês:

Solid organ transplantation has greatly improved survival in children with end-stage disease, becoming one of the main treatment options in this population. Nonetheless, there are significant challenges associated with validating and optimizing the effects of these interventions in clinical trials. Therefore, we reviewed the main issues related to conducting clinical transplantation research in children. We divided these challenges into three different categories: (i) challenges related to surgical techniques and anesthetic procedures, (ii) challenges related to post-transplant care and (iii) challenges specific to a particular population group and disease type. Some of the observed burdens for clinical research in this field are related to the limitations of conducting studies with a placebo or sham procedure, determining the standard of care for a control group, low prevalence of cases, ethical concerns related to use of a placebo control group and lack of generalizability from animal studies and clinical trials conducted in adult populations. To overcome some of these barriers, it is necessary to utilize alternative clinical trial designs, such as observational studies or non-inferiority trials, and to develop multicenter collaborations to increase the recruitment rate. In conclusion, the lack of robust data related to pediatric transplantation remains problematic, and further clinical trials are needed to develop more efficacious and safer treatments.