Effect of macrovescicular steatosis and other donor and recipient characteristics on the outcome of liver transplantation

L-carnitine ameliorates abnormal vulnerability of steatotic rat livers to cold ischemic preservation

BACKGROUND

Up to 30% of all livers retrieved for organ transplantation exhibit steatotic transformations. Chronic organ-donor shortage has led to the acceptance of these organs for transplantation, although a higher risk of graft nonfunction is associated with the preservation of steatotic livers.

METHODS

A dietary steatosis was induced in Wistar rats by fasting them for 2 days and feeding them with a fat-free diet. Fatty livers (n=14) were retrieved and flushed with 60 mL of histidine, tryptophane, alpha-ketoglutarate (HTK) solution. In half of the experiments, L-carnitine (5 mM) was added to the HTK. Functional integrity of the livers was evaluated by isolated reperfusion with KHB in a recirculating system at 37 degrees C for 45 minutes.

RESULTS

Addition of L-carnitine to the HTK promoted a significant reduction of the enzyme leakage from the livers upon reperfusion. Release of alanine-aminotransferase was reduced to one third (127+/-22 vs. 423+/-61 U/L), and the loss of glutamate dehydrogenase in the perfusate could be reduced significantly (42+/-7 vs. 542+/-134 U/L) when compared with livers stored without additional medication. Morphologic corroboration of these data was obtained by electron microscopy. Although normal appearance of liver mitochondria was preserved at the end of the cold ischemic storage, reperfusion of cold-stored fatty livers entailed massive alterations and frequent destruction of hepatic mitochondria. However, these morphologic impairments were remarkably mitigated in the carnitine-treated group.

CONCLUSIONS

L-carnitine represents a feasible metabolic adjunct for a safe and more successful preservation of ischemia-reperfusion-sensitive steatotic livers.

In vitro interleukin-6 treatment prevents mortality associated with fatty liver transplants in rats

BACKGROUND & AIMS

Orthotopic liver transplantation is currently the only curative therapy for chronic end-stage liver disease and acute liver failure. However, a scarcity of cadaveric donors has led to a critical shortage of organs available for transplant. This is further complicated by the prevalence of steatosis in about 13%-50% of donor livers, which is associated with a high risk of dysfunction and primary nonfunction.

METHODS

Steatotic Zucker rat livers and livers from alcohol-fed rats were transplanted into lean control rats. Liver injury, activation of survival signals, and hepatic microcirculation were compared in nontreated and interleukin-6 (IL-6)-treated steatotic isografts.

RESULTS

IL-6 pretreatment of steatotic Zucker rat liver isografts dramatically reduces mortality and liver injury following transplantation. Reperfusion after transplantation induces significant sinusoidal endothelial cell necrapoptosis in steatotic Zucker rat liver isografts, which is prevented by in vitro IL-6 pretreatment. IL-6 treatment activates cell survival signal transducer and activator of transcription factor 3 (STAT3) in hepatocytes and sinusoidal endothelial cells. Laser Doppler imaging and microsphere analyses demonstrate that IL-6 treatment markedly improves hepatic microcirculation, which is impaired in steatotic Zucker rat liver transplants. Finally, in vitro IL-6 treatment of donor livers also markedly reduces mortality associated with fatty liver transplants from alcohol-fed rats.

CONCLUSIONS

IL-6 induces hepatoprotection of steatotic liver isografts via preventing sinusoidal endothelial cell necrapoptosis and consequent amelioration of hepatic microcirculation, and protecting against hepatocyte death. IL-6 pretreatment of steatotic livers may render such allografts useable for clinical transplantation.

Clinical experience gained from the use of 120 steatotic donor livers for orthotopic liver transplantation

Steatosis of the donor liver is known to impact on patient and allograft outcome after orthotopic liver transplantation (OLT). The aim of this study is to evaluate the effect of increasing grades of cadaveric donor liver steatosis on recipient outcome. Between January, 1986 and December, 2000, 120 OLTs were performed with 72 mild, 25 moderate, and 23 severe steatotic donor livers. Donors of steatotic livers were more likely to be older (P =.001) and have died of intracerebral haemorrhage than donors of nonsteatotic livers. Initial poor graft function (IPF) was more common in donor livers with either moderate or severe steatosis than in donor livers with mild steatosis (P =.03). Primary graft nonfunction (PNF) occurred in only 1 donor liver with severe steatosis. PGE1 (PGE1) usage was higher in recipients of donor livers with moderate or severe steatosis versus donor livers with mild steatosis (P =.001). Allograft loss was greater at 1 year both in the moderate and severe (P =.03) steatotic liver groups. Patient survival at 3 months and overall allograft survival both were impacted negatively by increasing grades of donor liver steatosis (P =.02, P =.03). Three-month allograft survival was reduced in the steatotic donor livers if the donor was 50+ years old (P =.033). Recipient status at OLT (P =.001) and donor steatosis (P =.046) impacted on 30 day allograft survival (multivariate analysis). In conclusion, increasing grades of donor liver steatosis were associated with worse IPF and increased PGE1 usage. There was a negative impact of steatosis on both recipient and early allograft survival.

The effect of donor body mass index on primary graft nonfunction, retransplantation rate, and early graft and patient survival after liver transplantation

Previous studies have suggested that moderate donor liver steatosis is associated with an increased incidence of primary graft nonfunction (PGNF), delayed graft function, early graft loss, and retransplantation rates. The objective of our study was to determine the effect of donor body mass index (dBMI), after adjusting for other known confounding variables, on PGNF, early graft failure, retransplantation rate, and patient survival. The United Network for Organ Sharing (UNOS) database (1987 to 2001) of 22,303 adult patients, excluding patients of pediatric age (age less than 18 years) and those with multiple organ transplantations, living donors, and retransplantations, was used for this study. Based on the BMI (kg/m(2)) of the organ donor, transplant recipients were divided into four groups as follows: BMI < 25 (group 1, n = 11,660), 25 to 29.9 (group 2, n = 7418), 30 to 34.9 (group 3, n = 2301), and > or = 35 (group 4, n = 924). Information on donor liver histology was available for 1603 patients who underwent transplantation after 1999, and this subgroup was divided into three groups based on severity of steatosis (group A, < 20%; group B, 20% to 35%; group C, > 35%). Incidence of PGNF and early retransplantation rates were similar in groups 1 to 4 and in groups A, B, and C. Logistic regression analysis showed that dBMI or severity of steatosis was not a predictor of PGNF and early retransplantation. Cox regression analysis, after adjusting for confounding variables, showed similar patient and graft survival at 1 month and 1, 2, and 5 years for groups 1 to 4, and at 1 month and 6 months for groups A, B, and C. Severe donor obesity or moderate steatosis did not influence short-term and long-term outcome of liver transplantation.

The optimal number of donor biopsy sites to evaluate liver histology for transplantation

Macrovesicular steatosis (MaS), fibrosis, and inflammation have been associated with poor graft function after liver transplantation. We evaluated histological variation in livers to determine the optimal number of biopsies to estimate pathological characteristics in livers for transplantation. Specimens from autopsies performed during 3 months in 16- to 70-years-olds without known liver disease or drug and/or alcohol abuse were examined. Eight needle biopsies were performed, and hematoxylin and eosin-stained slides were evaluated. Percentages of MaS and microvesicular steatosis (MiS) were determined, and inflammation and fibrosis were scored as 0 to 4. MaS correlated positively with MiS, and inflammation correlated positively with fibrosis, whereas patient weight showed a significant correlation with liver weight and body mass index. No patient characteristic showed a significant correlation with histological findings. Subjects 55 years and older showed no increase in pathological findings compared with those younger than 55 years. When any site was compared with the average of the other sites, Spearman's rho correlation ranged from 0.89 to 0.95 for MaS, 0.89 to 0.94 for MiS, 0.54 to 0.80 for inflammation, and 0.66 to 0.80 for fibrosis. Two biopsies explained 95% of variations for MaS and MiS and 85% for inflammation and fibrosis. There was no significant difference between findings in the right and left lobes of livers. These findings suggest that no single site best predicts pathological findings, and there is little variation among sites. In borderline cases of MaS, significant pathological characteristics may be found in additional biopsies. Therefore, we recommend two biopsy sites to evaluate donor livers with suspicious clinical histories.

Extracorporeal suture technique for suprahepatic caval anastomosis in liver transplantation

BACKGROUND

During liver transplantation, an oversized graft or active bleeding in the hepatic area can make performance of the suprahepatic caval anastomosis extremely difficult or even impossible. In other instances, a brief as possible warm ischemia is desired to provide a marginal graft with maximum chances of good functioning.

METHODS

In order to manage those conditions, a suture technique was devised that allows the construction of a substantial part of the suprahepatic caval anastomosis keeping the graft outside the abdomen of the recipient.

RESULTS

Over a 12-month period, the technique was applied in 7 out of 148 transplants (5%). The 7 cases presented one or more of the following conditions: significant oversize mismatch (n = 6), active bleeding in the hepatic area (n = 1), and marginal graft (n = 4). Warm ischemia time averaged 27 minutes, a value not significantly different from the mean warm ischemia time of 25 minutes recorded in the easier transplants in which the conventional technique was used (P = 0.2467).

CONCLUSIONS

This extracorporeal suture technique allows construction of the suprahepatic caval anastomosis in critical situations arising during liver transplantation and avoidance of the prolonged warm ischemia that could be expected in such cases.