Normothermic machine perfusion (NMP) is emerging as a novel preservation strategy. During NMP, the organ is maintained in a metabolically active state that may not only provide superior organ... Show moreNormothermic machine perfusion (NMP) is emerging as a novel preservation strategy. During NMP, the organ is maintained in a metabolically active state that may not only provide superior organ preservation, but that also facilitates viability testing before transplantation, and ex situ resuscitation of marginal kidney grafts. Although the prevailing perfusion protocols for renal NMP are refined from initial pioneering studies concerning short periods of NMP, it could be argued that these protocols are not optimally tailored to address the putatively compromised metabolic plasticity of marginal donor grafts (i.e., in the context of viability testing and/or preservation), or to meet the metabolic prerequisites associated with prolonged perfusions and the required anabolic state in the context of organ regeneration. Herein, we provide a theoretical framework for the metabolic requirements for renal NMP. Aspects are discussed along the lines of carbohydrates, fatty acids, amino acids, and micronutrients required for optimal NMP of an isolated kidney. In addition, considerations for monitoring aspects of metabolic status during NMP are discussed. Show less
Objective: To explore putative different impacts of delayed graft function (DGF) on long-term graft survival in kidneys donated after brain death (DBD) and circulatory death (DCD).Background:... Show moreObjective: To explore putative different impacts of delayed graft function (DGF) on long-term graft survival in kidneys donated after brain death (DBD) and circulatory death (DCD).Background: Despite a 3-fold higher incidence of DGF in DCD grafts, large studies show equivalent long-term graft survival for DBD and DCD grafts. This observation implies a differential impact of DGF on DBD and DCD graft survival. The contrasting impact is remarkable and yet unexplained.Methods: The impact of DGF on DBD and DCD graft survival was evaluated in 6635 kidney transplants performed in The Netherlands. DGF severity and functional recovery dynamics were assessed for 599 kidney transplants performed at the Leiden Transplant Center. Immunohistochemical staining, gene expression profiling, and Ingenuity Pathway Analysis were used to identify differentially activated pathways in DBD and DCD grafts.Results: While DGF severely impacted 10-year graft survival in DBD grafts (HR 1.67; P < 0.001), DGF did not impact graft survival in DCD grafts (HR 1.08; P = 0.63). Shorter dialysis periods and superior posttransplant eGFRs in DBD grafts show that the differential impact was not caused by a more severe DGF phenotype in DBD grafts. Immunohistochemical evaluation indicates that pathways associated with tissue resilience are present in kidney grafts. Molecular evaluation showed selective activation of resilience-associated pathways in DCD grafts.Conclusions: This study shows an absent impact of DGF on long-term graft survival in DCD kidneys. Molecular evaluation suggests that the differential impact of DGF between DBD and DCD grafts relates to donor-type specific activation of resilience pathways in DCD grafts. Show less
Delayed graft function (DGF) following kidney transplantation affects long-term graft function and survival and is considered a manifestation of ischemia reperfusion injury. Preclinical studies... Show moreDelayed graft function (DGF) following kidney transplantation affects long-term graft function and survival and is considered a manifestation of ischemia reperfusion injury. Preclinical studies characterize metabolic defects resulting from mitochondrial damage as primary driver of ischemia reperfusion injury. In a comprehensive approach that included sequential establishment of postreperfusion arteriovenous concentration differences over the human graft, metabolomic and genomic analysis in tissue biopsies taken before and after reperfusion, we tested whether the preclinical observations translate to the context of clinical DGF. This report is based on sequential studies of 66 eligible patients of which 22 experienced DGF. Grafts with no DGF immediately recovered aerobic respiration as indicated by prompt cessation of lactate release following reperfusion. In contrast, grafts with DGF failed to recover aerobic respiration and showed persistent adenosine triphosphate catabolism indicated by a significant persistently low post reperfusion tissue glucose-lactate ratio and continued significant post-reperfusion lactate and hypoxanthine release (net arteriovenous difference for lactate and hypoxanthine at 30 minutes). The metabolic data for the group with DGF point to a persistent post reperfusion mitochondrial defect, confirmed by functional (respirometry) and morphological analyses. The archetypical mitochondrial stabilizing peptide SS-31 significantly preserved mitochondrial function in human kidney biopsies following simulated ischemia reperfusion. Thus, development of DGF is preceded by a profound post-reperfusion metabolic deficit resulting from severe mitochondrial damage. Strategies aimed at preventing DGF should be focused on safeguarding a minimally required post-reperfusion metabolic competence. Show less
