Novel oxygenation technique for hypothermic machine perfusion of liver grafts: Validation in porcine Donation after Cardiac Death (DCD) liver model.

BACKGROUND: Hypothermic oxygenated machine perfusion improves outcomes in Liver Transplantation, but application is limited as O2 is supplied by a stationary circuit. A novel technique of O2 "pre-charge" in a portable pump would broaden use and further mitigate ischemia damage from organ transport. METHODS: Porcine DCD livers were randomized to static cold storage (SCS, n = 8) or hypothermic machine perfusion (HMP). HMP was stratified into HMP-O2 (n = 5), non-O2 open to air HMP-RA (n = 5), and non-O2 with sealed lids or no air HMP-NA (n = 5). HMP-O2 was "pre-charged" using 100% O2 delivered at 10 L/min over 15 min. Perfusate and tissue O2 tension (pO2), liver biopsies, and fluid chemistries were analyzed. RESULTS: "Pre-charge" achieves sustained tissue and perfusate pO2 vs others. HMP-O2 results in decreased markers of hepatocyte injury: ALT (p < 0.05) and LDH (p < 0.05), lower expression of CRP and higher expression of SOD1 vs SCS. This suggests decreased inflammation and improved ROS scavenging. CONCLUSIONS: "Pre-charge" is an effective technique, which allows portability and transport without an O2 source and improves graft parameters.

Organ Procurement Organization Survey of Practices and Beliefs Regarding Prerecovery Percutaneous Liver Biopsy in Donation After Neurologic Determination of Death.

BACKGROUND: Prerecovery liver biopsy (PLB) allows histological evaluation of the organ before procurement. The opinions and what factors might influence PLB use within Organ Procurement Organizations (OPOs) are unknown. METHODS: A survey instrument was distributed by the Association of OPOs to the clinical directors of all 58 OPOs. Descriptive statistics were calculated. Results were also stratified based on OPO characteristics. RESULTS: Forty-nine (84.5%) of 58 OPOs responded to the survey; 40 (81.6%) of 49 currently perform PLB. This did not vary based on land mass, population, livers discarded, transplanted, donor age, or recipient MELD scores. Donor age, obesity, alcohol abuse, hepatitis serology, liver only donor, imaging results, and transplant center request were the most common indications for PLB in over 80% of OPOs. The median rate of performance is 5% to 10% of donors. Most use interventional radiologists to perform and the donor hospital pathologist/s to interpret PLB. Most OPOs believe PLBs are safe, reliable, useful, and performed often enough. Most say they did not believe they are easy to obtain. Beliefs were mixed regarding accuracy. The topics likely to influence PLB use were utility and accuracy of PLB, and availability of staff to perform PLB. OPOs that perform PLB more often were more likely to have favorable opinions of safety and pathologist availability, and more influenced by safety, reliability, availability, and a national consensus on the use of PLB. CONCLUSIONS: Considerable variability exists in the use of PLB. Additional information on the utility, accuracy, and safety of PLB are needed to optimize its use.

Prerecovery liver biopsy in the brain-dead donor: a case-control study of logistics, safety, precision, and utility.

Prerecovery liver biopsy (PLB) can potentially to decrease futile recovery and increase utilization of marginal brain-dead donor (BDD) livers. A case-control study was conducted to examine the logistics, safety, histological precision, and liver utilization associated with PLB in BDDs. Twenty-three cases between January 2008 and January 2013 were compared to 2 groups: 48 sequential and 69 clinically matched controls. Compared to the sequential controls, the cases were older (53 versus 46 years), heavier (30.2 versus 25.8 kg/m2), had higher prevalences of hypertension (78.3% versus 44.7%) and alcohol use (56.5% versus 23.4%), and a lower United Network for Organ Sharing expected organ yield (0.73 versus 0.81 livers/donor; P < 0.05 for all). Baseline characteristics were similar between cases and clinical controls. Donor management time was longer for the cases (22.4 hours) versus sequential controls (16.5 hours, P = 0.01) and clinical controls (15.9 hours, P = 0.01). Complications for cases (8.7%) were not different from either group of controls (18.8% for sequential controls, P = 0.46; 17.4% for clinical controls, P = 0.50). The agreement between the donor hospital and study pathologists was substantial regarding evaluation of steatosis (κ = 0.623) and fibrosis (κ = 0.627) and moderate regarding inflammation (κ = 0.495). The proportions of livers that were transplanted were similar for the cases and the clinical controls (60.9% versus 59.4%). In contrast, the proportion of donors for whom liver recovery was not attempted was higher (30.4% versus 8.7%), and the proportion of attempted liver recoveries that did not result in transplantation was lower (8.7% versus 31.9%). These differences were significant at P = 0.009. Overall, PLB is logistically feasible with only a minimal delay and is safe, its interpretation at donor hospitals is reproducible, and it appears to decrease futile liver recovery.

Does liver ischemic preconditioning in brain death donors induce kidney preconditioning? A retrospective analysis.

BACKGROUND: It is unclear whether ischemic preconditioning (IPC) of solid organs induces remote IPC (RIPC) in donors after brain death (DBD). METHODS: Outcomes in kidney recipients from 163 DBD in two randomized trials of liver IPC (5 min=62 and 10 min=101) were obtained retrospectively from the Scientific Registry of Transplant Recipients. Controls were kidney recipients from donors without IPC. Mean cold ischemia times were less than 20 hr. Primary outcomes were delayed graft function, defined as dialysis during the first posttransplantation week, and death-censored graft survival. Secondary outcomes were duration of initial hospital stay, patient survival, and estimated glomerular filtration rate 6, 12, 36, and 60 months after transplantation. RESULTS: After exclusions (40 kidneys not recovered, 21 not transplanted, 8 en bloc, 23 with extrarenal organs, and 6 with missing records), 228 recipients were included. Delayed graft function occurred in 23% of No RIPC and 28% of RIPC kidneys (P=0.54). One- and 3-year graft survival rates were 92% and 90%, respectively, in the No RIPC and 90% and 81%, respectively, in the RIPC group (P=0.12), and mean hospital stay was 9.3±13.9 and 9.7±8.2 days, respectively (P=0.15). There were no significant between group differences in patient survival and estimated glomerular filtration rate at any time point. CONCLUSIONS: Despite design and power limitations, our results suggest that liver IPC in DBD is of no clinical benefit to kidney recipients. Inconsistent efficacy and impracticality severely limit the usefulness of IPC in DBD. Other modalities of preconditioning should be tested.

Review of randomized clinical trials of donor management and organ preservation in deceased donors: opportunities and issues.

Given the static number of deceased donors, improvements in donor management and organ preservation to increase the number and quality of organs transplanted per donor are more pressing. Because controlled trials provide the best evidence, we conducted a review of English-language literature of trials in donor management and organ preservation to provide a compendium and to promote additional discussion and studies. Eighty-seven reports were retrieved: 13 on hemodynamic and fluid management, 7 on immunosuppressants, 12 on preconditioning, 34 on preservation fluids, and 21 on pulsatile perfusion. Sixteen studies are ongoing. Although hormonal therapy is used widely, additional studies are needed to determine the benefit of thyroid hormone and insulin replacement and to optimize steroid regimens. Dopamine's success in reducing kidney delayed graft function highlights the opportunity for additional preconditioning trials of remote ischemia, gases, opioids, and others. More rapid progress requires addressing unique barriers in consent and research approval, legal constraints precluding research in cardiac death donors, and streamlining collaboration of multiple stakeholders. With little interest from industry, federal funding needs to be increased. While the University of Wisconsin solution still reigns supreme, several promising preservative solutions and additives with not only biophysical but also pharmacological effects are on the cusp of phase 1 to 2 trials. After nearly three decades of uncertainty, the recent success of a European trial has reenergized the topic not only of machine preservation of the kidney but also of other organs evident by trials in progress. However, the costs of such technical innovations merit the burden of rigorous proof from controlled trials.

Global gene expression profiles of ischemic preconditioning in deceased donor liver transplantation.

The benefits of ischemic preconditioning (IPC) in reducing ischemia/reperfusion injury (IRI) remain indistinct in human liver transplantation (LT). To further understand mechanistic aspects of IPC, we performed microarray analyses as a nested substudy in a randomized trial of 10-minute IPC in 101 deceased donor LTs. Liver biopsies were performed after cold storage and at 90 minutes postreperfusion in 40 of 101 subjects. Global gene expression profiles in 6 biopsy pairs in IPC and work standard organ recovery groups at both time points were compared using the Affymetrix GeneChip Human Gene 1.0 ST array. Transcripts with >1.5-fold change and P < 0.05 were considered significant. IPC altered expression of 82 transcripts in antioxidant, immunological, lipid biosynthesis, cell development and growth, and other groups. Real-time polymerase chain reaction and immunoblotting validated our microarray data. IPC-induced overexpression of glutathione S-transferase mu transcripts (GSTM1, GSTM3, GSTM4, and GSTM5) was accompanied by increased protein expression and may contribute to a decrease in oxidative stress. However, the increased expression of fatty acid synthase may increase oxidative stress, and tumor necrosis factor ligand superfamily member 10 may promote apoptosis. These changes, in combination with decreased expression of heparin-binding epidermal growth factor-like growth factor and insulin-like growth factor binding protein-1, both of which inhibit apoptosis, may increase IRI. In our study of deceased donor LT, IPC induces changes in gene expression, some of which are potentially beneficial but some which are potentially injurious. Thus, our findings of changes in gene expression mirror the outcomes in our clinical trial.

Ischemic preconditioning of the liver: a few perspectives from the bench to bedside translation.

Utilization of ischemic preconditioning to ameliorate ischemia/reperfusion injury has been extensively studied in various organs and species for the past two decades. While hepatic ischemic preconditioning in animals has been largely beneficial, translational efforts in the two clinical contexts--liver resection and decreased donor liver transplantation--have yielded mixed results. This review is intended to critically examine the translational data and identify some potential reasons for the disparate clinical results, and highlight some issues for further studies.

Albumin peptide: a molecular marker for trauma/hemorrhagic-shock in rat mesenteric lymph.

Vascular permeability and endothelial cell damage has been shown to occur in rats subjected to trauma with hemorrhagic-shock. Although the factors responsible for the endothelial cell injury are unknown, it has been hypothesized that toxic factors produced in response to hemorrhagic-shock originate in the gut and are absorbed into the mesenteric lymphatics. Consistent with this hypothesis, it has been shown that lymph collected from animals subjected to trauma with hemorrhagic-shock (T/HS) results in a marked decrease in endothelial cell viability both in vitro and in vivo. We therefore compared the lymph collected pre-T/HS to samples collected during, and up to 3h post-T/HS in order to identify a factor present or increased in post-T/HS lymph. This analysis revealed that a single cationic peptide band was significantly increased in post-T/HS lymph, but not in lymph from control animals subjected to trauma without hemorrhagic-shock (T/SS). This peptide was subsequently identified as the N-terminal 24 amino acids of rat serum albumin (RSA) by mass spectrometry and amino acid sequencing. Although the measured increase in the albumin peptide correlates with detectable shock lymph-induced endothelial cell toxicity, the peptide was not toxic to endothelial cells. We therefore propose that the significant increase in the albumin peptide is a marker for post-T/HS lymph-induced endothelial cell toxicity.

Trauma-hemorrhagic shock mesenteric lymph from rat contains a modified form of albumin that is implicated in endothelial cell toxicity.

It has been proposed that factors originating from the gut after severe trauma/shock are introduced into the systemic circulation through the mesenteric lymphatics and are responsible for the cellular injury and inflammation that culminates in acute multiple organ dysfunction syndrome (MODS). Indeed, it has been shown that lymph collected from shocked but not sham-shocked animals causes endothelial cell death, neutrophil activation, and bone marrow (BM) colony growth suppression in vitro. In an attempt to isolate the factor(s) in lymph responsible for endothelial cell toxicity, lymph from shock and sham animals was fractionated by solid phase extraction (SPE) and ion exchange chromatography (IEX). The separation of shock lymph by both methodologies yielded two fractions having major detectable toxicity to endothelial cells, whereas no toxicity was detected from sham lymph separations by either method. Subsequent analysis of each SPE toxic fraction by gel electrophoresis and mass spectrometry suggests the toxicity is associated with a modified form of rat serum albumin (mod-RSA) and multiple lipid-based factors. Therefore, we have been able to demonstrate by two different separation techniques that shock lymph contains two or more factors that may account for the toxicity to endothelial cells. Further investigations are needed to determine the type of RSA modification and the identity of the lipid factors and their role in MODS.

Role of oxidative stress in the increased activation of signal transducers and activators of transcription-3 in the fatty livers of obese Zucker rats.

BACKGROUND: Fatty livers have chronic oxidative stress, which could activate several transcription factors. We hypothesized that fatty livers of obese rats have increased activation of signal transducers and activators of transcription-1 and transcription-3 (Stat-1 and Stat-3) and that tocopherol treatment will decrease Stat activation. METHODS: Obese (Ob) and lean (Ln) Zucker rats with or without tocopherol treatment were used. Western blots of liver nuclear and cytoplasmic extracts to assess phosphorylated and total Stat-3 and tyrosine kinases Jak-2 and Tyk-2, immunohistochemistry to assess distribution of phosphoStat-3, and gel shift assays to assess Stat and nuclear factor kappa B binding were performed. Interleukin-6 serum levels and hepatic transcripts were determined by immunoassay and reverse polymerase chain reaction with Southern blotting, respectively. RESULTS: Livers of Ob animals had increased nuclear phosphoStat-3, decreased cytoplasmic Stat-3, and increased Stat-3 binding. Serum interleukin-6 was not measurable in either Ob or Ln animals and hepatic transcript levels were not significantly different. Tocopherol administration decreased nuclear phosphoStat-3, increased cytoplasmic Stat-3, and decreased Stat-3 binding activity. CONCLUSIONS: Chronic oxidative stress in fatty livers is associated with increased Stat-3 activation and decreased cytosolic Stat-3. Tocopherol treatment decreases Stat-3 activation and increases cytosolic Stat-3. Tocopherol-induced changes in Stat-3 may play a role in its beneficial effects in hepatic ischemia in fatty livers.