Current issues in pediatric transplantation

Demographic Factors, Medication Adherence, and Post-transplant Health Outcomes: A Longitudinal Multilevel Modeling Approach

Few studies in pediatric solid organ transplantation have examined non-adherence to immunosuppressive medication over time and its associations with demographic factors and post-transplant outcomes including late acute rejection and hospitalizations. We examined longitudinal variation in patient Medication Level Variability Index (MLVI) adherence data from pediatric kidney, liver, and heart transplant recipients. Patient and administrative data from the United Network for Organ Sharing were linked with electronic health records and MLVI values for 332 patients. Multilevel mediation modeling indicated comparatively more variation in MLVI values between patients than within patients, longitudinally, over 10 years post transplant. MLVI values significantly predicted late acute rejection and hospitalization. MLVI partially mediated patient factors and post-transplant outcomes for patient age indicating adolescents may benefit most from intervention efforts. Results demonstrate the importance of longitudinal assessment of adherence and differences among patients. Efforts to promote medication adherence should be adapted to high-risk patients to increase likelihood of adherence.

Surgical Management and Outcomes of Patients with Multifocal Hepatoblastoma

OBJECTIVE

To compare the outcomes of patients with multifocal hepatoblastoma (HB) treated at our institution with either orthotopic liver transplant (OLTx) or hepatic resection to determine outcomes and risk factors for recurrence.

BACKGROUND

Multifocality in HB has been shown to be a significant prognostic factor for recurrence and worse outcome. The surgical management of this type of disease is complex and primarily involves OLTx to avoid leaving behind microscopic foci of disease in the remnant liver.

METHODS

We performed a retrospective chart review on all patients <18 years of age with multifocal HB treated at our institution between 2000 and 2021. Patient demographics, operative procedure, post-operative course, pathological data, laboratory values, short- and long-term outcomes were analyzed.

RESULTS

A total of 41 patients were identified as having complete radiologic and pathologic inclusion criteria. Twenty-three (56.1%) underwent OLTx and 18 (43.9%) underwent partial hepatectomy. Median length of follow-up across all patients was 3.1 years (IQR 1.1-6.6 years). Cohorts were similar in rates of PRETEXT designation status identified on standardized imaging re-review (p = .22). Three-year overall survival (OS) estimate was 76.8% (95% CI: 60.0%-87.3%). There was no difference in rates of recurrence or overall survival in patients who underwent either resection or OLTx (p = .54 and p = .92 respectively). Older patients (>72 months), patients with a positive porta hepatis margin, and patients with associated tumor thrombus experienced worse recurrence rates and survival. Histopathology demonstrating pleomorphic features independently associated with worse rates of recurrence.

CONCLUSIONS

Through proper patient selection, multifocal HB was adequately treated with either partial hepatectomy or OLTx with comparable outcome results. HB with pleomorphic features, increased patient age at diagnosis, involved porta hepatis margin on pathology, and the presence of associated tumor thrombus may be associated with worse outcomes regardless of the local control surgery offered.

LEVEL OF EVIDENCE

III.

Prediction of Outcomes After Heart Transplantation in Pediatric Patients Using National Registry Data: Evaluation of Machine Learning Approaches

BACKGROUND

The prediction of posttransplant health outcomes for pediatric heart transplantation is critical for risk stratification and high-quality posttransplant care.

OBJECTIVE

The purpose of this study was to examine the use of machine learning (ML) models to predict rejection and mortality for pediatric heart transplant recipients.

METHODS

Various ML models were used to predict rejection and mortality at 1, 3, and 5 years after transplantation in pediatric heart transplant recipients using United Network for Organ Sharing data from 1987 to 2019. The variables used for predicting posttransplant outcomes included donor and recipient as well as medical and social factors. We evaluated 7 ML models-extreme gradient boosting (XGBoost), logistic regression, support vector machine, random forest (RF), stochastic gradient descent, multilayer perceptron, and adaptive boosting (AdaBoost)-as well as a deep learning model with 2 hidden layers with 100 neurons and a rectified linear unit (ReLU) activation function followed by batch normalization for each and a classification head with a softmax activation function. We used 10-fold cross-validation to evaluate model performance. Shapley additive explanations (SHAP) values were calculated to estimate the importance of each variable for prediction.

RESULTS

RF and AdaBoost models were the best-performing algorithms for different prediction windows across outcomes. RF outperformed other ML algorithms in predicting 5 of the 6 outcomes (area under the receiver operating characteristic curve [AUROC] 0.664 and 0.706 for 1-year and 3-year rejection, respectively, and AUROC 0.697, 0.758, and 0.763 for 1-year, 3-year, and 5-year mortality, respectively). AdaBoost achieved the best performance for prediction of 5-year rejection (AUROC 0.705).

CONCLUSIONS

This study demonstrates the comparative utility of ML approaches for modeling posttransplant health outcomes using registry data. ML approaches can identify unique risk factors and their complex relationship with outcomes, thereby identifying patients considered to be at risk and informing the transplant community about the potential of these innovative approaches to improve pediatric care after heart transplantation. Future studies are required to translate the information derived from prediction models to optimize counseling, clinical care, and decision-making within pediatric organ transplant centers.

Advances in familial hypercholesterolaemia in children

Familial hypercholesterolaemia is a common, dominantly inherited disease that results in high concentrations of low-density lipoprotein cholesterol and in premature cardiovascular disease. To prevent cardiovascular disease and premature mortality, patients with the condition need to be identified and to start treatment early in life. In this Review, we discuss the treatment of heterozygous and homozygous familial hypercholesterolaemia in children, including lifestyle modifications, current pharmacological treatment options, and promising novel lipid-lowering treatments. In particular, these new therapies are expected to improve outcomes for patients with severe heterozygous familial hypercholesterolaemia or statin intolerance. For patients with homozygous familial hypercholesterolaemia, lipoprotein apheresis is currently the most valuable therapy available, but new approaches might reduce the need for this effective yet invasive, time-consuming, and expensive treatment.

Machine learning-based prediction of health outcomes in pediatric organ transplantation recipients

OBJECTIVES

Prediction of post-transplant health outcomes and identification of key factors remain important issues for pediatric transplant teams and researchers. Outcomes research has generally relied on general linear modeling or similar techniques offering limited predictive validity. Thus far, data-driven modeling and machine learning (ML) approaches have had limited application and success in pediatric transplant outcomes research. The purpose of the current study was to examine ML models predicting post-transplant hospitalization in a sample of pediatric kidney, liver, and heart transplant recipients from a large solid organ transplant program.

MATERIALS AND METHODS

Various logistic regression, naive Bayes, support vector machine, and deep learning (DL) methods were used to predict 1-, 3-, and 5-year post-transplant hospitalization using patient and administrative data from a large pediatric organ transplant center.

RESULTS

DL models generally outperformed traditional ML models across organtypes and prediction windows with area under the receiver operating characteristic curve values ranging from 0.750 to 0.851. Shapley additive explanations (SHAP) were used to increase the interpretability of DL model results. Various medical, patient, and social variables were identified as salient predictors across organ types.

DISCUSSION

Results demonstrate the utility of DL modeling for health outcome prediction with pediatric patients, and its use represents an important development in the prediction of post-transplant outcomes in pediatric transplantation compared to prior research.

CONCLUSION

Results point to DL models as potentially useful tools in decision-support systems assisting physicians and transplant teams in identifying patients at a greater risk for poor post-transplant outcomes.

Efficacy and safety of fumaric acid esters in young patients aged 10-17 years with moderate-to-severe plaque psoriasis: a randomized, double-blinded, placebo-controlled trial

BACKGROUND

Apart from biologics, no systemic drugs are approved in Europe for children with moderate-to-severe psoriasis. Retrospective observational studies have shown promising results for fumaric acid esters (FAE) in this setting.

OBJECTIVES

To show superiority of FAE over placebo in terms of treatment response after 20 weeks in children and adolescents aged 10-17 years.

METHODS

In a multicentre, randomized, double-blind, placebo-controlled phase IIIb study, patients aged 10-17 years with moderate-to-severe plaque psoriasis requiring systemic therapy were randomized 2 : 1 to receive FAE (n = 91) or placebo (n = 43) over 20 weeks, followed by an open-label FAE treatment phase. The coprimary endpoints were ≥ 75% improvement in Psoriasis Area and Severity Index (PASI 75) and Physician's Global Assessment (PGA) score of 0 or 1 (clear or almost clear) at week 20. The study was registered with EudraCT number 2012-000035-82.

RESULTS

At week 20, 55% [95% confidence interval (CI) 0·44-0·65] of FAE-treated patients achieved a PASI 75 response vs. 19% (95% CI 0·08-0·33) in the placebo group (absolute difference 36%, 95% CI 0·20-0·53; P < 0·001). In total, 42% (95% CI 0·32-0·53) in the FAE group vs. 7% (95% CI 0·01-0·19) in the placebo group achieved a PGA score of 0 or 1 at week 20 (absolute difference 35%, 95% CI 0·21-0·49; P < 0·001). During the double-blind period, drug-related adverse events occurred more frequently in patients receiving FAE compared with placebo (76% vs. 47%). Gastrointestinal disorders were the most common adverse events.

CONCLUSIONS

FAE administered over a period of 20 weeks demonstrated a better response than placebo; the difference was statistically significant and clinically meaningful. Application up to 40 weeks was generally well tolerated. However, further studies are required.

Identification of Factors Affecting Tacrolimus Trough Levels in Latin American Pediatric Liver Transplant Patients

Tacrolimus is the cornerstone in pediatric liver transplant immunosuppression. Despite close monitoring, fluctuations in tacrolimus blood levels affect safety and efficacy of immunosuppressive treatments. Identifying the factors related to the variability in tacrolimus exposure may be helpful in tailoring the dose. The aim of the present study was to characterize the clinical, pharmacological, and genetic variables associated with systemic tacrolimus exposure in pediatric liver transplant patients. De novo transplant patients with a survival of more than 1 month were considered for inclusion and were genotyped for cytochrome P450 3A5 (CYP3A5). Peritransplant clinical factors and laboratory covariates were recorded retrospectively between 1 month and 2 years after transplant, including alanine aminotransferase (ALT), aspartate aminotransferase, hematocrit, and tacrolimus predose steady-state blood concentrations collected 12 hours after tacrolimus dosing. A linear mixed effect (LME) model was used to assess the association of these factors and the log-transformed tacrolimus dose-normalized trough concentration (logC0/D) levels. Bootstrapping was used to internally validate the final model. External validation was performed in an independent group of patients who matched the original population. The developed LME model described that logC0/D increases with increases in time after transplant (β = 0.019, 95% confidence interval [CI], 0.010-0.028) and ALT values (β = 0.00030, 95% CI, 0.00002-0.00056), whereas logC0/D is significantly lower in graft CYP3A5 expressers compared with nonexpressers (β = -0.349, 95% CI, -0.631 to -0.062). In conclusion, donor CYP3A5 genotype, time after transplant, and ALT values are associated with tacrolimus disposition between 1 month and 2 years after transplant. A better understanding of tacrolimus exposure is essential to minimize the occurrence of an out-of-range therapeutic window that may lead to adverse drug reactions or acute rejection.

Unique clinical conditions associated with different acinar regions of fibrosis in long-term surviving pediatric liver grafts

In the majority of long-term survivors after PLTx, graft fibrosis has been identified. Recently, subtypes of graft fibrosis have been described based on their predominant acinar localization. We aimed to evaluate whether the development of portal, perisinusoidal, and centrilobular distribution of graft fibrosis is related to patient or transplantation-related parameters. We reviewed the histological features in protocol liver biopsies taken at 1 and 5 years after PLTx of 47 children on a tacrolimus-based immunosuppressive regimen. Fibrosis was assessed according to the LAFSc. The prevalence of portal fibrosis increased from 31% to 62%, sinusoidal from 68% to 79%, and centrilobular from 76% to 85%. The presence of portal fibrosis was associated with total bilirubin and γGT levels (each P<.02) and tended to be associated with biliary complications (P=.06). Sinusoidal fibrosis was associated with prior rejection episodes (P<.02) and centrilobular fibrosis with the presence of HLA mismatches (P=.02). In conclusion, using the LAFSc, we found a high incidence of progressive fibrosis in the 1-year and 5-year protocol biopsies after PLTx. Progression of fibrosis was observed in all acinar compartments, and each of the three locations is associated with different clinical conditions.

Adherence and the pediatric transplant patient

Adherence is proving to be the Achilles heel of pediatric transplantation. Through a careful literature review on adherence in pediatric solid-organ transplantation from 2007 to 2017, this chapter reports on the incidence, measuring tools, and consequences of poor adherence. We detail adherence determinants and interventions proposed to foster it. While adherence is a major problem in the adolescent age, it clearly is not limited to this age group. Importantly, it is not one to start tackling at that time or when it becomes apparent. Rather, fostering adherence should be built throughout the continuum of the transplant journey, starting in the pretransplantation phase. Adherence is clearly a fluid state, necessitating frequent reassessments and enforcement. Adherence in addition shares similar determinants with quality of life. The severe consequences in the case of poor adherence mandate that the transplant community prioritize it as the next frontier in transplantation. Good adherence is what will pave the road to tolerance, cost-efficient transplantation, and optimized long-term outcomes.

Retrospective data collection of psoriasis treatment with fumaric acid esters in children and adolescents in Germany (KIDS FUTURE study)

BACKGROUND

Given that there is no standard systemic treatment for children and adolescents with plaque psoriasis, this non-interventional, multicenter, retrospective study collected data on the efficacy and safety of long-term treatment with fumaric acid esters (FAEs) in this particular patient group.

PATIENTS AND METHODS

In patients younger than 18 years of age at the start of FAE treatment, data on efficacy and safety was retrospectively collected for at least 36 months.

RESULTS

Data from 127 patients (aged 6-17 years) was collected for treatment durations of up to 60 months. Physician's Global Assessment, Psoriasis Area and Severity Index, and Body Surface Area showed marked improvement in the first six months. After 36 months, these parameters had, on average, improved by up to two-thirds of baseline values. Thirty-seven patients experienced at least one adverse event (AE), which was FAE-related in 36 individuals. Three AEs (proteinuria (one case), flushing (two cases)) persisted during the observation period while on treatment. Fifteen AEs led to the discontinuation of therapy; nearly all of these cases were related to gastrointestinal disorders.

CONCLUSIONS

The KIDS FUTURE study - for the first time - included a larger population of children and adolescents with psoriasis who were treated with FAEs. The data obtained suggests that long-term FAE therapy in this patient group may be effective and safe. The results are currently being verified in an ongoing clinical study.

Pediatric liver transplantation: predictors of survival and resource utilization

PURPOSE

We sought to identify factors associated with increased resource utilization and in-hospital mortality for pediatric liver transplantation (LT).

METHODS

Kids' Inpatient Database (1997-2009) was used to identify cases of LT in patients <20 years old.

RESULTS

Overall, 2905 cases were identified, with an in-hospital survival of 91 %. LT was performed most frequently in < 5 year olds (61 %), females (51 %), and Caucasians (56 %). LT was performed at urban teaching hospitals (97 %) and facilities with children's units (51 %). Indications included pathologic conditions of the biliary tract (44 %) and inborn errors of metabolism (34 %), though unspecified end stage liver disease was the most common (75 %). Logistic regression found higher mortality in children undergoing LT for malignant conditions (odds ratio: 4.8) and acute hepatic failure (OR 3.4). Cases complicated by renal failure (OR 7.7) and complications of LT (OR 2.7) had higher mortality rates. Resource utilization increased for children with renal failure and those with hemorrhage as a complication of LT, p < 0.05.

CONCLUSION

Hospital survival is predicted by indication and complications associated with LT. Resource utilization increased with renal failure and complications related to LT. Admission length was sensitive to payer status, hospital characteristics, and UNOS region, whereas total costs were unaffected by payer status or hospital type.

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS

The calcineurin inhibitor tacrolimus is the cornerstone of most immunosuppressive treatment protocols after solid organ transplantation in the United States. Tacrolimus is a narrow therapeutic index drug and as such requires therapeutic drug monitoring and dose adjustment based on its whole blood trough concentrations. To facilitate home therapeutic drug and adherence monitoring, the collection of dried blood spots is an attractive concept. After a finger stick, the patient collects a blood drop on filter paper at home. After the blood is dried, it is mailed to the analytical laboratory where tacrolimus is quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in combination with a simple manual protein precipitation step and online column extraction. For tacrolimus analysis, a 6-mm disc is punched from the saturated center of the blood spot. The blood spot is homogenized using a bullet blender and then proteins are precipitated with methanol/0.2 M ZnSO4 containing the internal standard D2,(13)C-tacrolimus. After vortexing and centrifugation, 100 µl of supernatant is injected into an online extraction column and washed with 5 ml/min of 0.1 formic acid/acetonitrile (7:3, v:v) for 1 min. Hereafter, the switching valve is activated and the analytes are back-flushed onto the analytical column (and separated using a 0.1% formic acid/acetonitrile gradient). Tacrolimus is quantified in the positive multi reaction mode (MRM) using a tandem mass spectrometer. The assay is linear from 1 to 50 ng/ml. Inter-assay variability (3.6%-6.1%) and accuracy (91.7%-101.6%) as assessed over 20 days meet acceptance criteria. Average extraction recovery is 95.5%. There are no relevant carry-over, matrix interferences and matrix effects. Tacrolimus is stable in dried blood spots at RT and at +4 °C for 1 week. Extracted samples in the autosampler are stable at +4 °C for at least 72 hr.

Keys to long-term care of the liver transplant recipient

Improvements in overall survival early after liver transplantation result in a growing number of patients with the potential for long-term survival. Data available on long-term survival, to date, reflect the situation of patients who received their liver transplant during a very different health-care era. Translating these data into the current medical era of liver transplantation is an important task, as a better understanding of aspects associated with morbidity and mortality is fundamental in improving the long-term outcome of liver transplant recipients. Malignancy screening, optimal treatment of recurrent disease and adequate management of metabolic disease are crucial contributions to advance patient care. In this Review, data specific to the liver transplant recipient will be evaluated and, in the absence of sufficient evidence at this time, recommendations and guidelines for the general population on management of long-term concerns will be assessed for their applicability after liver transplantation. In addition, other preventive strategies relating to pregnancy, contraception and vaccination are reviewed in detail.

What determines ageing of the transplanted liver?

BACKGROUND

Liver transplantation is used to treat patients with irreversible liver failure from a variety of causes. Long-term survival has been reported, particularly in the paediatric population, with graft survival longer than 20 years now possible. The goal for paediatric liver transplantation is to increase the longevity of grafts to match the normal life expectancy of the child. This paper reviews the literature on the current understanding of ageing of the liver and biomarkers that may predict long-term survival or aid in utilization of organs.

METHODS

Scientific papers published from 1950 to 2013 were sought and extracted from the MEDLINE, PubMed and University of Melbourne databases.

RESULTS

Hepatocytes appear resistant to the ageing process, but are affected by both replicative senescence and stress-related senescence. These processes may be exacerbated by the act of transplantation. The most studied biomarkers are telomeres and SMP-30.

CONCLUSION

There are many factors that play a role in the ageing of the liver. Further studies into biomarkers of ageing and their relationship to the chronological age of the liver are required to aid in predicting long-term graft survival and utilization of organs.

Use of mesenchymal stem cells to treat liver fibrosis: Current situation and future prospects

Progressive liver fibrosis is a major health issue for which no effective treatment is available, leading to cirrhosis and orthotopic liver transplantation. However, organ shortage is a reality. Hence, there is an urgent need to find alternative therapeutic strategies. Cell-based therapy using mesenchymal stem cells (MSCs) may represent an attractive therapeutic option, based on their immunomodulatory properties, their potential to differentiate into hepatocytes, allowing the replacement of damaged hepatocytes, their potential to promote residual hepatocytes regeneration and their capacity to inhibit hepatic stellate cell activation or induce their apoptosis, particularly via paracrine mechanisms. The current review will highlight recent findings regarding the input of MSC-based therapy for the treatment of liver fibrosis, from in vitro studies to pre-clinical and clinical trials. Several studies have shown the ability of MSCs to reduce liver fibrosis and improve liver function. However, despite these promising results, some limitations need to be considered. Future prospects will also be discussed in this review.

The World Transplant Games: an incentive to improve physical fitness and habitual activity in pediatric solid organ transplant recipients

This prospective, interventional study examined the impact of training for the WTG on levels of health-related physical fitness and habitual activity in a cohort of pediatric SOT recipients. Physical fitness (FitnessGram(®) ) and habitual activity (HAES) measures were performed on participants (n = 19) in the WTG and compared to non-participant controls (n = 14) prior to and following the WTG. Pre-WTG exercise training was provided to participants. Participants demonstrated a statistically significant improvement in their habitual weekday (6.1 ± 1.7 to 8.5 ± 1.9 h; p = 0.002) and weekend (6.3 ± 2.6 to 8.4 ± 2.5 h; p = 0.01) activity over the training period, while controls improved weekday activity only (6.3 ± 2.0 to 8.3 ± 2.1 h; p = 0.05. Weekend activity: 7.7 ± 2.7 to 8.3 ± 2.3 h; p = 0.68). Participants demonstrated a non-statistical improvement in select physical fitness parameters; however, a greater number of participants achieved healthy criterion standards for cardiovascular fitness (2 vs. 1), abdominal strength (5 vs. 3), and upper body strength (7 vs. 3) following training and participating in the WTG. The WTG can provide a positive incentive for greater levels of physical activity and promote improvements in physical fitness levels. Further study is needed to examine long-term impact on lifestyle changes and health outcomes.

Pediatric liver transplantation: where do we stand? Where we are going to?

Pediatric liver transplantation (LT) is one of the most successful solid organ transplants with long-term survival more than 80%. Many aspects have contributed to improve survival, especially advancements in pre-, peri- and post-transplant management. The development of new surgical techniques, such as split-LT and the introduction of living related LT, has extended LT to small infants. Progress in the last 30 years has also been characterized by the introduction of calcineurin inhibitors. One problem remains the lack of donors. Donation after cardiac death offers a new possibility to increase the pool of potential donors. In children with acute liver failure, increasing interest has centered on the possibility of providing temporary liver support based on extracorporeal devices or hepatocyte transplantation. Similarly, hepatocyte transplantation offers new perspective in children with metabolic failure. As long-term survival increases, attention has now focused on the quality of life achieved by children undergoing LT.

Pediatric renal transplantation: results and prognostic factors

BACKGROUND/OBJECTIVE

As renal transplantation may increase survival rates and improve quality of life for children with end-stage renal disease, we investigated the long-term outcomes and prognostic factors of pediatric renal transplantation.

METHODS

A retrospective study was conducted to review 25 pediatric renal transplantations, either from live or deceased donors, in our hospital from 1995 to 2008. The cumulative graft survival rate was calculated using the Kaplan-Meier method. Log rank tests were employed to identify categorical prognostic factors for graft survival of the pediatric renal transplantations, and Cox regression analysis for numeric factors.

RESULTS

The mean age of our study subjects was 11.63±3.76 years, and the mean follow-up period was 49.24±33.72 months. The 12-month and 36-month graft survival rates were 92% and 82.14%, respectively. The rejection-free survival rates were 88% and 72.88% in the first and third years, respectively. All of the patients were alive during the follow-up period. Acute rejection (p=0.0175) and male sex (p=0.0384) were found to be significant factors for graft survival.

CONCLUSION

For pediatric patients, we found that renal transplantation is now a safe and effective surgical procedure for children with end-stage renal disease. Acute rejection and male gender were identified as prognostic factors for poor graft survival.

Qualitätsmerkmale und Strukturvoraussetzungen für pädiatrische Lebertransplantationszentren

Durch die Entwicklung verschiedener, innovativer Operationstechniken vor allem zur Größenadaptation von Lebertransplantaten wurde die Voraussetzung geschaffen, Lebertransplantationen auch bei kleinen Kindern (einschließlich Neugeborenen und Säuglingen) erfolgreich durchzuführen. Auf der Basis der Fortschritte in den operativen Techniken und der Immunsuppression hat sich seit den 1980er Jahren die pädiatrische Lebertransplantation auch in Deutschland zum Standardverfahren bei akutem oder chronischem Leberversagen sowie bei einer Reihe von hepatisch bedingten Stoffwechselerkrankungen etabliert (Ng et al. 2008; Kelly 2006). Aufgrund dieser Fortschritte sowie der Fortschritte im Bereich der pädiatrischen Transplantationshepatologie und der pädiatrischen Intensivmedizin werden heute in spezialisierten pädiatrischen Lebertransplantationszentren bei meist guter Rehabilitation im Vergleich zu Erwachsenenkollektiven vergleichbare 1-Jahres-Überlebensraten (bis zu >90 %), bei deutlich höheren Langzeitüberlebensraten (>90 %) erreicht (Melter 2012). Das Hauptaugenmerk der klinischen Versorgung liegt daher inzwischen darauf, mit einer entsprechenden medizinischen Nachsorge die vor allen Dingen medikamentenassoziierte Morbidität und Letalität im Langzeitverlauf zu minimieren (Ojo et al. 2003).

Novel histologic scoring system for long-term allograft fibrosis after liver transplantation in children

The existing systems for scoring fibrosis were not developed to evaluate transplanted livers. Our aim was to design and validate a novel fibrosis scoring system specifically adapted to assess liver allograft fibrosis (LAF). Clinical data, histology, transient elastography (TE) and AST/platelet ratio index (APRI) were reviewed in 38 pediatric liver transplant (LT) recipients. Protocol liver biopsies performed at 6 months and 7 years post-LT were reviewed by three pathologists who assessed LAF using the METAVIR and Ishak systems. LAF was also scored separately in portal (0-3), sinusoidal (0-3) and centrolobular areas (0-3). Scoring evaluations were correlated with fibrosis quantification using morphometry, and also with TE and APRI. Statistical correlations between morphometry and METAVIR were 0.571 (p < 0.000) and 0.566 (p < 0.000) for the Ishak system. The novel score (0-9) for separate assessment of portal, sinusoidal and centrolobular fibrosis showed a better correlation with morphometry (0.731; p < 0.000) and high intra-/interobserver agreement (0.966; p < 0.000 and 0.794; p < 0.000, respectively). No correlation was found between TE or APRI and morphometry or the three histologic scores. In conclusion, this novel semiquantitative fibrosis scoring system seems to more accurately reflect LAF than the existing scoring system and may become a practical tool for staging fibrosis in LT.

Telomere shortening and karyotypic alterations in hepatocytes in long-term transplanted human liver allografts

The long-term fate of aged liver allografts in young recipients who received grafts from older donors is unknown. We evaluated graft aging by analyzing hepatocytic telomere length and karyotypic changes. Seventeen pediatric individuals who underwent living-donor liver transplantation for congenital biliary diseases were selected. At a median of 10.4 years post-transplant, ten had tolerated grafts with weaned off immunosuppressants, and seven had idiopathic post-transplantation hepatitis. Fluorescence in situ hybridization was used to evaluate the telomere signal intensity (TI) and karyotypic changes. First, we measured predictive age-dependent TI decline with regression analysis of donor livers. The mean TI at the earliest (within a year) and latest biopsies was significantly lower than the predicted TI of the studied allografts. With univariate analysis, a higher abnormal karyotype ratio in the donor liver was correlated with development of idiopathic post-transplantation hepatitis. With multivariate analysis that included clinical parameters, a greater TI decline at the earliest biopsy was correlated with the development of idiopathic post-transplantation hepatitis. In conclusion, graft aging as measured by TI decline and donor abnormal karyotype ratio was associated with idiopathic post-transplantation hepatitis of long-term transplanted liver allografts.

Pregnancy following liver transplantation during childhood and adolescence

More than 80% of pediatric transplant recipients will survive to reach adulthood, and many will consider having children. We report on outcomes and management of five pregnancies in four women undergoing orthotopic liver transplantation during childhood or adolescence and followed up at our Transplant Center. A retrospective clinical folder audit was performed. Mean age at transplantation was 13.3 ± 3.4 yr (range, 10-18 yr). Mean interval between transplantation and pregnancy was 15.4 ± 4.9 yr (range, 10-22 yr). Mean maternal age at conception was 28 ± 3.5 yr (range, 23-32 yr). Mean gestational age was 36.6 ± 1.7 wk. Mean birth weight was 2672 ± 249 g. Immunosuppression was cyclosporin based in three women and tacrolimus based in one woman. Pregnancy complications necessitating the induction of labor included fetal distress and rising maternal liver enzymes in two women, cholestasis of pregnancy and impaired renal graft function in one woman, fetal distress and preeclampsia in one woman. Modes of delivery were normal vaginal delivery in three women and cesarean section in one woman. No maternal or fetal deaths and no congenital malformations occurred. No episodes of rejection occurred during pregnancy. Two women experienced acute cellular rejection requiring an increase in baseline immunosuppression in the first year, following delivery. No graft losses occurred during a mean follow-up of 44 ± 17.9 months post-delivery. With careful management, pregnancy post-liver transplantation can have a successful outcome.

Effects of rural status on health outcomes in pediatric liver transplantation: a single center analysis of 388 patients

Rural status of patients may impact health before and after pediatric LT. We used UI codes published by the USDA to stratify patients as urban or rural depending county residence. A total of 388 patients who had LT and who met criteria were included. Rejection, PTLD, and survival were used as primary outcome measures of post-LT health. UNOS Status 1 and PELD/MELD scores >20 were used as secondary outcome measures of poorer pre-LT health. Logistic regression models were run to determine associations. We did not find any statistically significant differences in pre- or post-LT outcomes with respect to rurality. Among rural patients, there was a general trend for decreased incidence of rejection (25.0% vs. 33.4%; OR 0.64, 95% CI 0.29-1.44), increased risk of PTLD (5.6% vs. 3.4%; OR 1.86, 95% CI 0.36-3.31), and decreased survival (OR 0.85, 95% CI 0.34-2.13) after LT. Rural patients also tended to be sicker at the time of LT than patients from urban areas, with increased proportion of Status 1 (OR 1.17, 95% CI 0.51-2.70) and PELD/MELD scores >20 (OR 1.20, 95% CI 0.59-2.45). From a single center experience, we conclude that rurality did not significantly affect health outcomes after LT, although a larger study may validate the general trends that rural patients may have decreased rejection, increased PTLD, and mortality, and be in poorer health at the time of LT.

Outcomes in pediatric solid-organ transplantation

LaR Pediatric solid-organ transplantation is an increasingly successful treatment for organ failure. Five- and 10-yr patient survival rates have dramatically improved over the last couple of decades, and currently, over 80% of pediatric patients survive into adolescence and young adulthood. Waiting list mortality has been a concern for liver, heart, and intestinal transplantation, illustrating the importance of transplant as a life-saving therapy. Unfortunately, the success of pediatric transplantation comes at the cost of long-term or late complications that arise as a result of allograft rejection or injury, immunosuppression-related morbidity, or both. As transplant recipients enter adolescence treatment, non-adherence becomes a significant issue, and the medical and psychosocial impacts transition to adulthood not only with regard to healthcare but also in terms of functional outcomes, economic potential, and overall QoL. This review addresses the clinical and psychosocial challenges encountered by pediatric transplant recipients in the current era. A better understanding of pediatric transplant outcomes and adult morbidity and mortality requires further ongoing assessment.

Viral hepatitis: retrospective review in a canadian pediatric hospital

Introduction. Clinical presentation of viral hepatitis ranges from mild symptoms to fulminant hepatitis. Our aim is to describe clinical presentation and outcomes of children with viral hepatitis from the Eastern Ontario/Western Quebec regions of Canada. Methods. Retrospective chart review of children diagnosed with viral hepatitis at our institution from January 1, 1998, to December 31, 2007. Results. There were 261 charts reviewed, only 64 had a confirmed viral etiology: 34 (53%) hepatitis B (HBV), 16 (25%) hepatitis C (HCV), 4 (6.3%) hepatitis A (HAV), 7 (11%) cytomegalovirus (CMV), and 3 (4.7%) Epstein-Barr virus (EBV). Children with HBV presented at a mean age of 6.4 ± 4.6 years. Spontaneous seroconversion (appearance of HBVeAb and loss of HBVeAg) occurred in 21/34 (61.7%). Children with acute hepatitis (HAV, CMV, and EBV) presented with mild abdominal pain, jaundice, and fevers. Overall outcome was excellent. Conclusion. Acute and chronic hepatitis in children has a benign course; moreover, HBV spontaneous seroconversion is common in pediatric patients.

The use of sirolimus as a rescue therapy in pediatric intestinal transplant recipients

To review our experience with SRL as a second-line therapy in our series of 45 SBTx recipients (1997-2009). Retrospective review of five children converted to SRL: 3 M/2 F; median of three yr old (range 20 months-18 yr); rescue indications, adverse events with SRL, resolution of tacrolimus-related side effects, incidence of rejection, PTLD, or GVHD were summarized. Tacrolimus was discontinued (average 13 months after transplant) because of refractory hemolytic anemia in four patients with decreased renal function and because of advanced renal failure and unclear neutropenia in one. PTLD and GVHD had been previously diagnosed in two. Tacrolimus-related side effects disappeared in all five although other immunosuppressants and splenectomy were used simultaneously or later in most of them. Adverse events reported after the conversion were infections (tuberculosis and Pneumocystis carinii in two) and mild hypertriglyceridemia. No rejection, GVHD, or PTLD episode was observed. Four patients are alive with excellent quality of life (median follow-up 18 months). Sirolimus is a safe rescue therapy in SBTx children when tacrolimus is not well tolerated. Renal function and hematologic disorders seem to improve, although other simultaneous strategies could be also involved. Further studies could demonstrate its efficacy as a first-line treatment.

Cytokine kinetics profiling in pediatric renal transplant recipients

Pediatric renal transplant recipients experience side effects of immunosuppression. Few immunoassays exist which can assess the adequacy of immunosuppression. We developed a CKT, whereby cytokine levels are measured in a five-day mixed lymphocyte reaction. We describe the in vitro cytokine responses to donor and third-party antigen in a pilot study of nine children after living-donor renal transplantation. The CKT identified five patterns of IFN-gamma secretion relative to donor and third-party alloantigen: no response to alloantigen (n = 2), hypo-response to donor (n = 3), equal response (n = 1), hyper-response to donor (n = 1), and intermediate response (n = 2). IL-2 and IL-13 patterning correlated with IFN-gamma expression. Two of nine subjects had acute rejection, which correlated with intermediate and hyper-responsive profiles. No rejection occurred during immunosuppression or donor-specific hypo-responsiveness. Significant immunosuppression was universal early after transplantation. Two of four children showed strong pretransplant responses to donor, which were regained three months post-transplant, and associated with rejection in one subject. The CKT reflects the level of immunosuppression and may offer a method to assess the adequacy of immunosuppression. A pattern of complete non-responsiveness or hypo-responsiveness correlated with lack of acute rejection. The CKT may prove useful in titrating immunosuppression and in improving live donor selection.

Expression of Phosphatidylserine-Specific Phospholipase A1 mRNA in Human THP-1-Derived Macrophages

The expression of phosphatidylserine-specific phospholipase A1 (PS-PLA1) is most upregulated in the genes of peripheral blood cells from chronic rejection model rats bearing long-term surviving cardiac allografts. The expression profile of PS-PLA1 in peripheral blood cells responsible for the immune response may indicate a possible biological marker for rejection episodes. In this study, PS-PLA1 mRNA expression was examined in human THP-1-derived macrophages. The effects of several immunosuppressive agents on this expression were also examined in in vitro experiments. A real-time RT-PCR analysis revealed that PS-PLA1 mRNA expression was found in human THP-1-derived macrophages. This expression was enhanced in the cells stimulated with lipopolysaccharide (LPS), a toll-like receptor (TLR) 4 ligand. Other TLR ligands (TLR2, 3, 5, 7, and 9) did not show a significant induction of PS-PLA1 mRNA. The time course of the mRNA expression profiles was different between PS-PLA1 and tumor necrosis factor-α (TNF-α), which showed a maximal expression at 12 and 1 h after LPS stimulation, respectively. Among the observed immunosuppressive agents, corticosteroids, prednisolone, 6α-methylprednisolone, dexamethasone, and beclomethasone inhibited PS-PLA1 expression with half-maximal inhibitory concentrations less than 3.0 nM, while methotrexate, cyclosporine A, tacrolimus, 6-mercaptopurine, and mycophenoic acid showed either a weak or moderate inhibition. These results suggest that the expression of PS-PLA1 mRNA in THP-1-derived macrophages is activated via TLR4 and it is inhibited by corticosteroids, which are used at high dosages to suppress chronic allograft rejection.

Liver transplantation in children: update 2010

Pediatric liver transplant recipients represent an important target population for primary care health professionals as well as transplant practitioners. With improving patient and graft survival, new concerns now face health care professionals caring for the transplant community, namely the long-term complications of immunosuppressive therapy and the potential for withdrawal of immunosuppression, transplant recipients' quality of life, and the persistent shortage of donor organs leading to morbidity and mortality on the waiting list. These issues require constant collaboration between pediatricians, transplant hepatologists, transplant surgeons, nurses, dieticians, social workers, psychologists, and other supporting services.

Meta-analysis of medical regimen adherence outcomes in pediatric solid organ transplantation

BACKGROUND

Adherence to the medical regimen after pediatric organ transplantation is important for maximizing good clinical outcomes. However, the literature provides inconsistent evidence regarding prevalence and risk factors for nonadherence posttransplant.

METHODS

A total of 61 studies (30 kidney, 18 liver, 8 heart, 2 lung/heart-lung, and 3 with mixed recipient samples) were included in a meta-analysis. Average rates of nonadherence to six areas of the regimen, and correlations of potential risk factors with nonadherence, were calculated.

RESULTS

Across all types of transplantation, nonadherence to clinic appointments and tests was most prevalent, at 12.9 cases per 100 patients per year (PPY). The immunosuppression nonadherence rate was six cases per 100 PPY. Nonadherence to substance use restrictions, diet, exercise, and other healthcare requirements ranged from 0.6 to 8 cases per 100 PPY. Only the rate of nonadherence to clinic appointments and tests varied by transplant type: heart recipients had the lowest rate (4.6 cases per 100 PPY vs. 12.7-18.8 cases per 100 PPY in other recipients). Older age of the child, family functioning (greater parental distress and lower family cohesion), and the child's psychological status (poorer behavioral functioning and greater distress) were among the psychosocial characteristics significantly correlated with poorer adherence. These correlations were small to modest in size (r=0.12-0.18).

CONCLUSIONS

These nonadherence rates provide benchmarks for clinicians to use to estimate patient risk. The identified psychosocial correlates of nonadherence are potential targets for intervention. Future studies should focus on improving the prediction of nonadherence risk and on testing interventions to reduce risk.

Biosafety in ex vivo gene therapy and conditional ablation of lentivirally transduced hepatocytes in nonhuman primates

Ex vivo gene therapy is an interesting alternative to orthotopic liver transplantation (OLT) for treating metabolic liver diseases. In this study, we investigated its efficacy and biosafety in nonhuman primates. Hepatocytes isolated from liver lobectomy were transduced in suspension with a bicistronic liver-specific lentiviral vector and immediately autotransplanted (SLIT) into three cynomolgus monkeys. The vector encoded cynomolgus erythropoietin (EPO) and the conditional suicide gene herpes simplex virus-thymidine kinase (HSV-TK). Survival of transduced hepatocytes and vector dissemination were evaluated by detecting transgene expression and vector DNA. SLIT was safely performed within a day in all three subjects. Serum EPO and hematocrit rapidly increased post-SLIT and their values returned to baseline within about 1 month. Isoforms of EPO detected in monkeys' sera differed from the physiological renal EPO. In liver biopsies at months 8 and 15, we detected EPO protein, vector mRNA and DNA, demonstrating long-term survival and functionality of transplanted lentivirally transduced hepatocytes. Valganciclovir administration resulted in complete ablation of the transduced hepatocytes. We demonstrated the feasibility and biosafety of SLIT, and the long term (>1 year) functionality of lentivirally transduced hepatocytes in nonhuman primates. The HSV-TK/valganciclovir suicide strategy can increase the biosafety of liver gene therapy protocols by safely and completely ablating transduced hepatocytes on demand.

Graft fibrosis after pediatric liver transplantation: ten years of follow-up

Previously we reported the presence of portal fibrosis in 31% (n = 84) of the grafts in protocol biopsies 1 year after pediatric liver transplantation (LTx). To assess the natural history of graft fibrosis after pediatric liver transplantation, we extended the analysis of graft histology in follow-up protocol biopsy specimens obtained 5 and 10 years after transplantation. We correlated histological results with clinical parameters at the time of LTx and during follow-up, to allow identification of risk factors for the development of fibrosis. From 1 year to 5 years after LTx, the prevalence of fibrosis increased from 31% to 65% (n = 66) but remained stable thereafter (at 10 years, 69%, n = 55). At 10 years after LTx, however, the percentage of patients with severe fibrosis had increased from 10% (at 5 years) to 29%. Of the 69% of children without fibrosis at 1 year post-transplantation, 64% (n = 39) had developed some degree of fibrosis at 10 years. Fibrosis was strongly related to transplant-related factors such as prolonged cold ischemia time, young age at the time of transplantation, high donor/recipient age ratio, and the use of partial grafts (P < 0.05). Fibrosis was not significantly related to rejection, chronic hepatitis, or the nature of the immunosuppressive therapy.

CONCLUSION

Biopsies after pediatric LTx show that most grafts developed fibrosis within 5 years. At 10 years after LTx, the graft fibrosis had progressed to severe fibrosis in at least 25% of the patients. Development of fibrosis, starting either before or after the first year post-LTx, was strongly related to transplant-related factors, indicating the importance of these factors to long-term graft prognosis.

Calcineurin inhibitor sparing in paediatric solid organ transplantation : managing the efficacy/toxicity conundrum

Despite their efficacy, the calcineurin inhibitors (CNIs) ciclosporin and tacrolimus carry a risk of debilitating adverse effects, especially nephrotoxicity, that affect the long-term outcome and survival of children who are given organ transplants. Simple reduction in dosage of CNI has little or no long-term benefit on their adverse effects, and complete withdrawal without threatening graft outcome may only be possible after liver transplantation. Until the last decade, the only option was to increase corticosteroid and/or azathioprine doses, which imposed additional long-term hazards. Considered here are the emerging generation of new agents offering an opportunity for improving long-term graft survival, minimizing CNI-related adverse events and ensuring patient well-being.A holistic, multifaceted strategy may need to be considered - initial selection and optimized use and monitoring of immunosuppressant regimens, early recognition of indicators of patient and graft dysfunction, and, where applicable, early introduction of CNI-sparing regimens facilitating CNI withdrawal. The evidence reviewed here supports these approaches but remains far from definitive in paediatric solid organ transplantation. Because de novo immunosuppression uses CNI in more than 93% of patients, reduction of CNI-related adverse effects has focused on CNI sparing or withdrawal.A recurring theme where sirolimus and mycophenolate mofetil have been used for this purpose is the importance of their early introduction to limit CNI damage and provide long-term benefit: for example, long-term renal function critically reflects that at 1 year post-transplant. While mycophenolic acid shows advantages over sirolimus in preserving renal function because the latter is associated with proteinuria, sirolimus appears the more potent immunosuppressant but also impairs early wound healing. The use of CNI-free immunosuppressant regimens with depleting or non-depleting antibodies plus sirolimus and mycophenolic acid needs much wider investigation to achieve acceptable rejection rates and conserve renal function. The adverse effects of the alternative immunosuppressants, particularly the dyslipidaemia associated with sirolimus, needs to be minimized to avoid replacing one set of adverse effects (from CNIs) with another. While we can only conjecture that judicious combinations with the second generation of novel immunosuppressants currently in development will provide these solutions, a rationale of low-dose therapy with multiple immunosuppressants acting by complementary mechanisms seems to hold the promise for efficacy with minimal toxicity until the vision of tolerance achieves reality.

Prophylaxis followed by preemptive therapy versus preemptive therapy for prevention of human cytomegalovirus disease in pediatric patients undergoing liver transplantation

Twenty-one pediatric liver transplant recipients were enrolled in a study comparing prophylaxis followed by preemptive therapy (10 patients) versus preemptive therapy alone (11 patients) for prevention of human cytomegalovirus (HCMV) disease. In the prophylaxis arm, patients were treated with ganciclovir for 30 days, then preemptive therapy was initiated with virologic monitoring for pp65 antigenemia. In the preemptive therapy arm, patients were treated on reaching 100,000 DNA copies/mL whole blood. An interim analysis showed that, although numbers of both infected and treated patients were comparable in the two arms, the median number of total days of antiviral therapy per patient (30 vs. 18, P<0.01) was significantly higher in the prophylaxis arm. No case of HCMV disease occurred in either arm. Therefore, the trial was interrupted and prophylaxis replaced with preemptive therapy alone. In parallel, the development of T-cell-mediated immune response was found to be comparable in both arms.

Non-adherence to post-transplant care: prevalence, risk factors and outcomes in adolescent liver transplant recipients

This study examined the prevalence, demographic variables and adverse outcomes associated with non-adherence to post-transplant care in adolescent liver transplant recipients. We conducted a retrospective chart review of 111 adolescent patients (age 12-21 yr) greater than six months post-transplantation and defined non-adherence as not taking the immunosuppressive(s) or not attending any clinic visit in 2005. Fifty subjects (45.0%) were non-adherent and 61 (55.0%) were adherent. Twenty percent of the subjects did not attend clinic and 10.9% did not complete laboratory tests. Non-adherence was significantly associated with fewer completed laboratory tests (p < 0.0001), single parent status (p < 0.0186), and older age and greater years post-transplantation by both univariate and multivariate analyses (p < 0.008, p < 0.0141 and p < 0.0012, p < 0.0174, respectively). Non-adherence to medication was significantly associated with a rejection episode in 31 patients (p < 0.0069) but not in the subgroup of seven patients who stopped their immunosuppression completely. Non-adherence to post-transplant care is a prevalent problem in adolescents particularly of an older age and greater years post-transplantation. Rejection was a significant consequence of medication non-adherence except in a subgroup with presumed graft tolerance who discontinued their immunosuppression. These results emphasize the need for strict monitoring of adherence to post-transplant care to improve long-term survival and quality of life in adolescent transplant patients.