Wayel Jassem

The role of mitochondria in ischemia/reperfusion injury

In organ transplantation, ischemia/reperfusion injury is a multifactorial process that leads to organ damage and primary graft dysfunction. Injury to the organ is mediated by a complex chain of events that involves depletion of energy substrates, alteration of ionic homeostasis, production of reactive oxygen species, and cell death by apoptosis and necrosis. There is increasing evidence that mitochondria play a role in this process because of the profound changes experienced during ischemia and reperfusion. Understanding the mechanisms that lead to mitochondrial damage may be important for developing strategies aimed at improving graft outcome. In this review, we examine the role of mitochondria in ischemia/reperfusion injury and the possible mechanisms that may contribute to organ dysfunction.

Single-center experience with liver transplantation from controlled non-heartbeating donors: a viable source of grafts.

Background:To increase the number of livers available for transplantation a non-heartbeating donor (NHBD) liver transplant program was started after obtaining hospital ethical committee approval. Methods:Controlled donors with a warm ischemia of <30 minutes were considered. A 5-minute stand-off period was observed from asystole to skin incision. A super-rapid technique was used for the retrieval. Methods used to assess the suitability for transplantation included liver function tests, morphologic and histologic assessment, and hepatocyte viability testing. Results:Sixty livers were retrieved from NHBDs. Of these, 33 were judged suitable for transplantation. Of these one was exported and transplanted, and one could not be matched to a suitable recipient. A further 27 were not used because of liver appearance in 21, prolonged hypoxia and hypotension in 4, poor perfusion in 1, and donor malignancy in 1. Mean donor age was 39.4 years (range, 0.75–67 years). Causes of death were head trauma in 10 donors, intracranial bleed in 24, and anoxic/ischemic brain injury in 26. Mean warm ischemia time was 14.7 minutes (range, 7–40 minutes). Thirty-two patients were transplanted (one split liver), and the mean age of the recipients was 38.4 years (range, 0.7–72 years). All grafts had good early function except one right lobe split. There were 4 deaths resulting from ischemic brain injury, chronic rejection, biliary sepsis, and multiorgan failure following retransplantation for primary nonfunction. Overall patient and graft survival is 87% and 84%, respectively, at a median follow-up of 15 months. Conclusions:Early results suggest that controlled NHBDs are a significant new source of grafts, but careful donor selection and short cold ischemia are mandatory.

Leukocyte infiltration and inflammatory antigen expression in cadaveric and living-donor livers before transplant1

Background. There is evidence to indicate that organs obtained from cadaveric donors may be injured as a result of inflammatory events occurring at around the time of brain death. The aim of this study was to investigate whether there are differences in the expression of proinflammatory molecules between cadaveric and living-donor livers before transplant and to determine whether there is any association with donor factors and posttransplant graft function. Methods. A comparison of biopsies obtained before implantation from cadaveric (n=22) and living-related donor (LRD) (n=10) livers was performed. Cryostat tissue sections were stained with antibodies to leukocyte subpopulations, adhesion molecules, and human leukocyte antigen class II antigens. Results. Significantly higher levels of CD3+ lymphocytes (1.5%±0.8% vs. 0.5%±0.3%; P =0.00004), CD68+ monocytes and macrophages (4.0%±1.2% vs. 2.7%±0.6%; P =0.0003), and Fas-ligand staining (4.2%±2.6% vs. 1.5%±1.1%; P =0.0003) were detected in cadaveric livers compared with LRD livers before transplantation. Furthermore, higher levels of intercellular adhesion molecule-1 expression were detected in cadaveric donor livers and found to be associated with longer periods of ventilation (P =0.01), infection in the donor (P =0.013), and administration of dopamine (P =0.03). Although there were no differences in neutrophil infiltration between cadaveric and LRD livers, significantly higher levels were found in cadaveric donors with infection (P =0.01). Conclusion. This study demonstrates that inflammatory changes occur in cadaveric donor livers and are associated with events occurring during the period of intensive care. These proinflammatory changes did not seem to affect the short-term clinical outcome of cadaveric liver allografts but may contribute to alloimmune responses and impairment of graft function in the long term.

Biliary complications after liver transplantation using grafts from donors after cardiac death: results from a matched control study in a single large volume center.

Objective:To assess the incidence and impact of biliary complications in recipients transplanted from donors after cardiac death (DCD) at one single large institution. Background:Shortage of available cadaveric organs is a significant limiting factor in liver transplantation (LT). The use of DCD offers the potential to increase the organ pool. However, early results with DCD liver grafts were associated with a greater incidence of ischemic cholangiopathy (IC), leading to several programs to abandoning this source of organs. Methods:A retrospective analysis of a prospective database from April 2001 to 2010 focused on 167 consecutive DCD-LT. Each DCD transplant was matched with 2 brain death donors (DBD) grafts (n = 333) according to the period of transplantation. Primary outcome measures were biliary complications including the severity of complications, graft survival and patient survival. Minimum follow-up was 3 months. Results:Anastomotic stricture was the most common biliary complication (DCD = 30, 19% vs. DBD = 41, 13%). Most were treated endocoscopically (grade IIIa = 72%), whereas hepatico-jejunostomy (grade IIIb) was performed in 22%. Primary IC occurred in 4 (2.5%) recipients from the DCD group and was absent in the DBD group (P = 0.005). However, none of these patients required retransplantation. Patient and graft survival at 1, 3, and 5 years were similar between DCD and DBD groups (P = 0.106, P = 0.138, P = 0.113, respectively). Conclusions:The encouraging results with DCD-LT are probably due to the selection of DCD grafts and clear definition of warm ischemia.

Ischemic preconditioning of cadaver donor livers protects allografts following transplantation.

Background. Ischemic preconditioning (IP) has been shown in animal models to protect livers against ischemia/reperfusion injury. The aim of this clinical study is to investigate whether IP of cadaver livers prior to retrieval confers protection on the allografts. Methods. Cadaveric donor livers were subjected to IP prior to retrieval by clamping of the hepatic pedicle for 10 min followed by reperfusion. Biopsies were obtained from the preconditioned (n=9) and control nonpreconditioned (n=14) liver transplants prior to and 2 hr following reperfusion. Cryosections were stained with antibodies against neutrophils and platelets. Results. IP livers were associated with significantly lower serum levels of aspartate aminotransferase (240±98 IU/L vs. 382±163 IU/L; P>0.016) and lactate (0.81±0.07 mmol/L vs. 1.58±0.9 mmol/L; P>0.018) 24 hr following transplantation. Furthermore, recipients of IP livers spent a significantly shorter time in the intensive care unit following transplantation compared to those given nonpreconditioned allografts (1 vs. 2.8±1.6 days; P=0.0008). Increases in neutrophil infiltration were detected in 6/14 (43%; P=0.022) and in CD41 deposition in 5/14 (36%; P=0.042) of nonpreconditioned livers. However, none of the IP allografts showed any change in the levels of platelets or neutrophil infiltration following transplantation. Conclusion. IP is an effective method of protecting cadaver donor allografts from cold ischemia and subsequent reperfusion injury. IP is also associated with a reduction in the nonspecific inflammatory response.

Cadaveric versus living-donor livers: differences in inflammatory markers after transplantation

Background. Prolonged cold storage of organs for transplantation may lead to inflammatory damage upon reperfusion. The aim of this study was to investigate whether organs from living donors experience less damage upon reperfusion than those retrieved from cadaver donors, where cold ischemia times are significantly longer. MethodS. Biopsies were obtained from cadaveric (n=23) and living-related donor (LRD) (n=10) liver transplants before and 2 hours after reperfusion. Cryosections were stained with antibodies against neutrophils, platelets, activated platelets, and endothelium. Results. LRD liver allografts showed minimal changes postreperfusion. In contrast, after reperfusion of cadaver allografts, neutrophil infiltration was detected in 22% and increased expression of von Willebrand factor (vWF), CD41, and P-selectin in 48%, 30%, and 13% of allografts, respectively. In cadaver allografts with deposition of activated platelets expressing either P-selectin or vWF, the cold ischemia time was significantly longer (885±123 min vs. 608±214 min, P =0.04; 776.8±171 min vs. 559.3±216 min, P =0.01, respectively). Increases in neutrophils and platelets after reperfusion were not significantly associated with clinical events posttransplant. However, in cadaver transplants that experienced early acute rejection, the mean cold ischemia time was significantly longer than in allografts with no rejection (732±174 min vs. 480±221 min, P =0.006). Conclusions. This study demonstrates that in the clinical situation, cold ischemia causes platelet deposition and neutrophil infiltration after reperfusion of cadaveric liver allografts. These early inflammatory events may contribute to make the graft more susceptible to acute rejection.

Gamma-glutamyltransferase and risk of cancer in a cohort of 545,460 persons : the Swedish AMORIS study

BACKGROUND Apart from using gamma-glutamyltransferase (GGT) as a predictor of diabetes, cardiovascular and chronic kidney disease, some evidence suggests GGT as an indicator of cancer risk. We aimed to study the association between GGT and cancer in a large Swedish cohort with 37,809 primary cancers. METHODS In a cohort of 545,460 persons (aged >20 years) who had a measurement of GGT in the Apolipoprotein Mortality Risk (AMORIS) study, multivariate Cox proportional hazards regression was used to investigate categories of GGT (<18, 18-36,36-72, ≥72 U/L) in relation to cancer risk. Stratified analyses were conducted by gender, levels of alanine aminotransferase (ALT) (</≥ 50 U/L), glucose (</≥ 6.11 mmol/L) and triglycerides (</≥1.71 mmol/L). RESULTS A positive association was found between categories of GGT and overall cancer risk (HR: 1.07 (95%CI: 1.04-1.09,), 1.18 (1.14-1.22), 1.32 (1.26-1.38) for the 2nd, 3rd and 4th categories compared to the 1st). Stratified analyses showed that for those with glucose ≥6.11 mmol/L, the association between GGT and risk of prostate, breast and liver cancer became stronger (e.g. HR for GGT ≥72 U/L and prostate cancer: 1.11 (0.98-1.26) and 1.35 (1.00-1.81) for glucose <6.11 and ≥6.11 mmol/L, respectively). With pancreatic cancer, the association with GGT was weaker for those with elevated glucose levels compared to those with normal levels. No effects of ALT or triglyceride levels on risk were found. CONCLUSION We found evidence of associations between elevated GGT and risk of developing different cancers. The strength of this association may vary by glucose levels because hyperglycaemia can result in oxidative stress initiating damaging pathways of carcinogenesis.

Secretory leukocyte protease inhibitor: a pivotal mediator of anti-inflammatory responses in acetaminophen-induced acute liver failure.

Acetaminophen‐induced acute liver failure (AALF) is characterized both by activation of innate immune responses and susceptibility to sepsis. Circulating monocytes and hepatic macrophages are central mediators of inflammatory responses and tissue repair processes during human AALF. Secretory leukocyte protease inhibitor (SLPI) modulates monocyte/macrophage function through inhibition of nuclear factor kappa B (NF‐κB) signaling. The aims of this study were to establish the role of SLPI in AALF. Circulating levels of SLPI, monocyte cluster of differentiation 163 (CD163), human leukocyte antigen‐DR (HLA‐DR), and lipopolysaccharide (LPS)‐stimulated levels of NF‐κBp65, tumor necrosis factor alpha (TNF‐α) and interleukin (IL)‐6 were determined in patients with AALF, chronic liver disease, and healthy controls. Immunohistochemistry and multispectral imaging of AALF explant tissue determined the cellular sources of SLPI and hepatic macrophage phenotype. The phenotype and function of monocytes and macrophages was determined following culture with recombinant human (rh)‐SLPI, liver homogenates, and plasma derived from AALF patients in the presence and absence of antihuman (α)SLPI. Hepatic and circulatory concentrations of SLPI were elevated in AALF and immunohistochemistry revealed SLPI expression in biliary epithelial cells and within hepatic macrophages (h‐mψ) in areas of necrosis. H‐mψ and circulating monocytes in AALF exhibited an anti‐inflammatory phenotype and functional characteristics; typified by reductions in NF‐κBp65, TNF‐α, and IL‐6 and preserved IL‐10 secretion following LPS challenge. Culture of healthy monocytes with AALF liver homogenates, plasma, or rhSLPI induced monocytes with strikingly similar anti‐inflammatory characteristics which were reversed by inhibiting the activity of SLPI. Conclusion: SLPI is a pivotal mediator of anti‐inflammatory responses in AALF through modulation of monocyte/macrophage function, which may account for the susceptibility to sepsis in AALF. (Hepatology 2014;59:1564‐1576)

Segmental Liver Transplantation from Non-Heart Beating Donors—An Early Experience with Implications for the Future

We report our experience of pediatric liver transplantation with partial grafts from non‐heart beating donors (NHBD). Controlled donors less than 40 years of age with a warm ischemia time (WI) of less than 30 min were considered for pediatric recipients. Death was declared 5 min after asystole. A super‐rapid recovery technique with aortic and portal perfusion was utilized. Mean donor age was 29 years and WI 14.6 min (range 11–18). Seven children, mean age 4.9 years (0.7–11), median weight 20 kg (8.4–53) received NHBD segmental liver grafts. Diagnoses included seronegative hepatitis, neonatal sclerosing cholangitis, familial intrahepatic cholestasis, hepatoblastoma, primary hyperoxaluria and factor VII deficiency (n = 2).The grafts included four reduced and one split left lateral segments, one left lobe and one right auxiliary graft. Mean cold ischemia was 7.3 h (6.2–8.8). Complications included one pleural effusion and one biliary collection drained percutaneously. At 20 months (10–36) follow‐up all children are alive and well with functioning grafts.

Non-heart-beating versus cadaveric and living-donor livers: differences in inflammatory markers before transplantation.

Background. Liver transplantation from non–heart-beating donors (NHBD) has been reintroduced into clinical practice to increase the donor pool; however, little is known about the immune status of NHBD livers. The aim of this study was to assess intragraft cell populations and inflammatory markers in NHBD and to compare the findings with cadaveric and living-related donor (LRD) livers. Methods. Biopsy specimens were obtained from controlled NHBD (n=9), conventional cadaveric (n=22), and living-donor (n=10) livers at the end of cold storage. Cryostat sections were stained for monocytes-macrophages, T lymphocytes, and intercellular adhesion molecule (ICAM)-1. Results. The levels of leukocyte infiltration in NHBD reflected those found in conventional cadaver donors and were significantly higher than in LRD livers. Similar levels of CD68+ monocytes-macrophages were detected in cadaver (4.0±1.2%) and NHBD livers (4.6±1.2%) and were significantly greater than in the LRD livers (2.6±0.5%, P <0.01). Furthermore, the levels of T lymphocytes in NHBD (1.1±0.6%) and cadaver donors (1.5±0.8%) were similar, and were higher than in LRD (vs. 0.47±0.3%, P <0.05). Twelve of 22 (60%) cadaver livers had high levels of ICAM-1 expression (grade 3), compared with only 1 of 10 (10%) LRD livers (P =0.02). Four of nine (44%) controlled NHBD livers expressed high levels of ICAM-1. Conclusions. The results demonstrate that livers obtained from controlled NHBD before transplantation are similar to conventional cadaver donors regarding the level of leukocyte infiltration. Nevertheless, lower levels of ICAM-1 were detected in NHBD, suggesting less exposure to inflammatory mediators than conventional cadaver donor livers.