Surgical advances in liver and bowel transplantation

Prevalence and Clinical Impact of Donor-Specific Alloantibody Among Intestinal Transplant Recipients

BACKGROUND

Rejection remains the leading cause of allograft loss, and a major barrier to improving long-term outcomes after intestinal transplantation. Our aim is to define the prevalence and investigate the role of donor-specific antibody (DSA) on intestinal graft outcomes.

METHODS

The study includes 109 transplants performed in 95 recipients at a single center. Patients were screened for DSA pretransplant, monitored regularly posttransplant and when clinically indicated using the single-antigen bead Luminex assay. Standard induction immunosuppression was with interleukin-2 receptor antagonists, and antithymocyte globulin in high-risk recipients. Maintenance regimens were tacrolimus-based.

RESULTS

Pretransplant DSA was detected in 12 (11%) recipients with 50% continuing to have circulating antibodies posttransplant. An additional 24 (25%) patients developed de novo DSA, and of these, 71% had persistent antibodies. Recipients with preformed DSA demonstrated elevated risks of early graft failure, whereas those with de novo DSA experienced accelerated graft loss once DSA was detected, reaching a 28% failure rate within 2 years. HLA-DQ mismatch is a significant risk factor for de novo DSA emergence, whereas the persistence of antibodies is predicted by DSA strength and specificity. Although inclusion of the liver in the intestinal allograft imparts an immunological advantage against rejection-related graft loss, this protective effect was lost among recipients with persistent DSA.

CONCLUSIONS

The presence of DSA is associated with inferior graft outcomes among intestinal transplant recipients. An enhanced understanding of the mechanisms by which DSA causes allograft injury, and effective strategies targeting humoral immune reactivity are needed to improve long-term intestinal graft outcomes.

Early detection of the graft failure after pediatric liver transplantation: a Bergamo experience

BACKGROUND

Effective indicators of the early graft failure after pediatric liver transplantation are currently a crucial question. The aim of this study was to analyze retrospectively laboratory parameters that may help anticipate an early graft loss (GL).

METHODS

The 131 pediatric liver transplantations, performed in our hospital from January 2002 to December 2005, were reviewed. Post-operative laboratory parameters, collected in the first 36 h of the Paediatric Intensive Care Unit (PICU) stay, were analyzed for children with both graft survival and GL. Receiver operating characteristics analysis was used to identify the optimal cut-off for the laboratory parameters. Multivariate logistic regression analysis was used to calculate the adjusted risk of GL for the prognostic parameters identified.

RESULTS

The mean age at transplant was 1.1 years. The two groups were comparable for all recipient and donor variables considered. Children with GL showed significantly higher levels of ammonia and transaminase at the admission to the PICU and higher levels of prothrombin time, creatinine, lactate and a lower level of platelets at the 36 h of PICU. The laboratory parameters over the cut-off value by the multivariate logistic regression identified all early thromboses earlier than Doppler ultrasound.

CONCLUSIONS

This study suggests that routine blood tests may help to anticipate an early loss of liver grafts in children after transplantation and may improve our diagnostic investigation in the case of thrombosis suspicion. Further validation by a prospective study is needed to carefully assess the sensitivity and specificity of the identified criteria.

Pretransplant predictors of survival after intestinal transplantation: analysis of a single-center experience of more than 100 transplants

INTRODUCTION

Outcomes after intestinal transplantation (ITx) have steadily improved. There are few studies that assess factors associated with these enhanced results. The purpose of this study was to examine peri-ITx variables and survival.

METHODS

A review of a prospectively maintained database was undertaken and included all patients undergoing ITx from 1991 to 2010. The study endpoints were patient and graft survival. Data collection included 44 variables. Survival was computed using Kaplan-Meier methods. Univariate analysis was conducted (log-rank test) with significance set at P less than or equal to 0.20. Multivariate analysis of significant variables was conducted using model reduction by backward elimination variable selection method with significance set at P less than 0.05.

RESULTS

Eighty-eight patients received 106 ITx. The majority of recipients were male, Latino, and children. The leading causes of intestinal and liver failure were gastroschisis and parenteral nutrition. Grafts transplanted were isolated intestine (24%), liver-intestine (62%), and multivisceral (14%). Overall 1- and 5-year patient and graft survival were 80% and 65%, and 74% and 64%, respectively. Significant univariate survival predictors were weight less than 20 kg, children, liver-inclusive allograft, panel reactive antibody less than 20%, absence of donor-specific antibody, negative crossmatch, warm ischemia time less than 60 min, absence of recipient splenectomy, interleukin-2 receptor antagonist induction, and era. Significant multivariate survival predictors were absence of donor-specific antibody, absence of recipient splenectomy, and liver-inclusive graft type.

CONCLUSION

This large, single-center ITx experience confirms a marked improvement in outcome over time. Several important factors were associated with survival, and these factors can potentially be adjusted before ITx. These findings should refocus future efforts on strategies to improve treatment and prevent graft loss.

Current concepts in the evaluation of patients for liver transplantation

Candidates for liver transplantation undergo a thorough medical, surgical, psychosocial and financial evaluation prior to listing for transplantation. Prioritization for allocating livers is based upon the model for end-stage liver disease score and waiting-time mortality with the fundamental concept of giving organs to the sickest first. In the upcoming years the allocation system may be modified to include other factors associated with mortality, such as serum sodium, and may incorporate both pre- and post-transplant mortality. Strategies to expand the donor pool include utilizing livers from donors after cardiac death, split liver transplantation and living donor liver transplantation. Future challenges for liver transplantation will include the obesity epidemic and the prevention and treatment of recurrent disease, particularly hepatitis C.