Yusuke Okamura

Pediatric Liver Transplantation Using Reduced and Hyper-Reduced Left Lateral Segment Grafts: A 10-Year Single-Center Experience

Few studies have examined the long‐term outcomes and prognostic factors associated with pediatric living living‐donor liver transplantation (LDLT) using reduced and hyper‐reduced left lateral segment grafts. We conducted a retrospective, single‐center assessment of the outcomes of this procedure, as well as clinical factors that influenced graft and patient survival. Between September 2000 and December 2009, 49 patients (median age: 7 months, weight: 5.45 kg) underwent LDLT using reduced (partial left lateral segment; n = 5, monosegment; n = 26), or hyper‐reduced (reduced monosegment grafts; n = 18) left lateral segment grafts. In all cases, the estimated graft‐to‐recipient body weight ratio of the left lateral segment was more than 4%, as assessed by preoperative computed tomography volumetry, and therefore further reduction was required. A hepatic artery thrombosis occurred in two patients (4.1%). Portal venous complications occurred in eight patients (16.3%). The overall patient survival rate at 1, 3 and 10 years after LDLT were 83.7%, 81.4% and 78.9%, respectively. Multivariate analysis revealed that recipient age of less than 2 months and warm ischemic time of more than 40 min affected patient survival. Pediatric LDLT using reduced and hyper‐reduced left lateral segment grafts appears to be a feasible option with acceptable graft survival and vascular complication rates.

Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting

The current drastic shortage of donor organs has led to acceptance of extended‐criteria donors for transplantation, despite higher risk of primary nonfunction. Here, we report the impact of subnormothermic machine perfusion (SMP) preservation on the protection of >50% macrosteatotic livers. Dietary hepatic steatosis was induced in Wistar rats via 2‐day fasting and subsequent 3‐day re‐feeding with a fat‐free, carbohydrate‐rich diet. This protocol induces 50–60% macrovesicular steatosis, which should be discarded when preserved via cold storage (CS). The fatty livers were retrieved and preserved for 4 h using either CS in histidine‐tryptophan‐ketoglutarate or SMP in polysol solution. Graft functional integrity was evaluated via oxygenated ex vivo reperfusion for 2 h at 37°C. SMP resulted in significant reductions in not only parenchymal alanine aminotransferase (p < 0.001), but also mitochondrial glutamate dehydrogenase (p < 0.001) enzyme release. Moreover, portal venous pressure (p = 0.047), tissue adenosine triphosphate (p = 0.001), bile production (p < 0.001), high‐mobility group box protein‐1 (p < 0.001), lipid peroxidation, and tissue glutathione were all significantly improved by SMP. Electron microscopy revealed that SMP alleviated deleterious alterations of sinusoidal microvasculature and hepatocellular mitochondria, both of which are characteristic disadvantages associated with steatosis. SMP could protect 50–60% macrosteatotic livers from preservation/reperfusion injury, and may thus represent a new means for expanding available donor pools.

Intestinal ischemic preconditioning ameliorates hepatic ischemia/reperfusion injury in rats: Role of heme oxygenase 1 in the second window of protection

Preconditioning by brief ischemia protects not only the concerned organ but also other distant organs against subsequent lethal damage; this is called remote ischemic preconditioning (RIPC). This study was designed to investigate the impact of intestinal RIPC on hepatic ischemia/reperfusion injury (IRI) with a special interest in heme oxygenase 1 (HO‐1) induction in the second window of protection (SWOP). Male Wistar rats were randomly assigned to 1 of 2 groups: an RIPC group or a sham group. Before hepatic IRI, either intestinal RIPC, consisting of 2 cycles of 4‐minute superior mesenteric artery clamping separated by 11 minutes of declamping (RIPC group), or a sham procedure (sham group) was performed. After 48 hours of recovery, the rats were exposed to 30 minutes of total hepatic IRI. Transaminase releases and proinflammatory cytokines were determined at several time points after reperfusion. Histopathological analysis and animal survival were also investigated. Intestinal RIPC significantly lowered transaminase release (alanine aminotransferase at 2 hours: 873.3 ± 176.4 IU/L for the RIPC group versus 3378.7 ± 871.1 IU/L for the sham group, P < .001) as well as proinflammatory cytokine production (tumor necrosis factor α at 2 hours: 930 ± 42 versus 387 ± 17 pg/μL, P < .001). The morphological integrity of the liver and the ileum was maintained significantly better with intestinal RIPC; this reached statistical significance not only in Suzukis liver injury score (3.5 ± 0.2 versus 0.7 ± 0.5, P = .007) but also in Parks score for intestinal damage (4.0 ± 0.4 versus 2.0 ± 0.2, P = .007). Animal survival was also markedly improved (83.1% versus 15.4%, P < .001). As a mechanism underlying this protection, HO‐1 was substantially induced in liver tissue, especially in hepatocytes, with remarkable up‐regulation of bradykinin in the portal blood, whereas HO‐1 protein induction in enterocytes was not significant. In conclusion, intestinal RIPC remarkably attenuates hepatic IRI in the SWOP, presumably by HO‐1 induction in hepatocytes. Liver Transpl 21:112‐122, 2015.

Role of preferential cyclooxygenase-2 inhibition by meloxicam in ischemia/reperfusion injury of the rat liver.

Background: Ischemia/reperfusion injury (IRI) is one of the major clinical problems in liver and transplant surgery. Livers subjected to warm ischemia in vivo often show a severe dysfunction and the release of numerous inflammatory cytokines and arachidonic acid metabolites. Cyclooxygenase (COX)-2 is the inducible isoform of an intracellular enzyme that converts arachidonic acid into prostaglandins. The aim of the study was to evaluate the effect of COX-2 inhibition and the role of Kupffer cells in IRI of the liver. Methods: Male Wistar rats [250- 280 g body weight (BW)] were anesthetized and subjected to 30-min warm ischemia of the liver (Pringles maneuver) and 60-min reperfusion after median laparotomy. The I/R group received no additional treatment. In the COX-2 inhibitor (COX-2I) group, the animals received 1 mg/kg BW meloxicam prior to operation. Gadolinium chloride (GdCl3) (10 mg/kg BW) was given 24 h prior to operation in the GdCl3 and GdCl3 + COX-2I groups for the selective depletion of Kupffer cells. The GdCl3 + COX-2I group received both GdCl3 and meloxicam treatment prior to operation. Blood and liver samples were obtained at the end of the experiments for further investigations. Results: After 30 min of warm ischemia in vivo, severe hepatocellular damage was observed in the I/R group. These impairments could be significantly prevented by the selective COX-2 inhibition and the depletion of Kupffer cells. Alanine aminotransferase was significantly reduced upon meloxicam and GdCl3 treatment compared to the I/R group: I/R, 3,240 ± 1,262 U/l versus COX-2I, 973 ± 649 U/l, p < 0.001; I/R versus GdCl3, 1,611 ± 600 U/l, p < 0.05, and I/R versus GdCl3 + COX-2I, 1,511 ± 575 U/l, p < 0.01. Plasma levels of tumor necrosis factor alpha (TNF-α) were significantly reduced in the COX-2I treatment group compared to I/R (3.5 ± 1.5 vs. 16.3 ± 11.7 pg/ml, respectively; p < 0.05). Similarly, the amount of TxB2, a marker for COX-2 metabolism, was significantly reduced in the meloxicam treatment groups compared to the I/R group: I/R, 22,500 ± 5,210 pg/ml versus COX-2I, 1,822 ± 938 pg/ml, p < 0.001, and I/R versus GdCl3 + COX-2I, 1,530 ± 907 pg/ml, p < 0.001. All values are given as mean ± SD (n = 6). Conclusion: These results suggest that the inhibition of COX-2 suppressed the initiation of an inflammatory cascade by attenuating the release of TNF-α, which is an initiator of the inflammatory reaction in hepatic IRI. Therefore, we conclude that preferential inhibition of COX-2 is a possible therapeutic approach against warm IRI of the liver.

Influence of hepatorenal syndrome on outcome of living donor liver transplantation: A single-center experience in 357 patients.

Liver transplantation is the only curative treatment for hepatorenal syndrome (HRS); however, the influence of HRS on the patient and renal outcome after living donor liver transplantation (LDLT) is still unclear. The aim of the present study was to evaluate the influence of HRS on the outcome of LDLT.

Key techniques for orthotopic liver transplantation model with a 30 % graft in swine

Liver transplantation (LT) with small-for-size (SFS) grafts is critically important to increase donor safety for living donor LT in Japan, and to overcome the donor shortages for cadaveric donor LT in the United States and Europe [1]. The development of clinically feasible models of orthotopic liver transplantation (OLT) with SFS grafts assists in the study of liver regeneration. We reported our porcine OLT model with a 30 % graft, describing anatomy, surgical procedures, and perioperative care [2]. Based on the current status of our ongoing study of this model, there are four keys to successful LT surgery:

Hydrogen Flush After Cold Storage (HyFACS), as a new end‐ischemic ex vivo treatment for liver grafts against ischemia/reperfusion injury

Cold storage (CS) remains the gold standard for organ preservation worldwide, although it is inevitably associated with ischemia/reperfusion injury (IRI). Molecular hydrogen (H2) is well known to have antioxidative properties. However, its unfavorable features, ie, inflammability, low solubility, and high tissue/substance permeability, have hampered its clinical application. To overcome such obstacles, we developed a novel reconditioning method for donor organs named hydrogen flush after cold storage (HyFACS), which is just an end‐ischemic H2 flush directly to donor organs ex vivo, and, herein, we report its therapeutic impact against hepatic IRI. Whole liver grafts were retrieved from Wistar rats. After 24‐hour CS in UW solution, livers were cold‐flushed with H2 solution (1.0 ppm) via the portal vein (PV), the hepatic artery (HA), or both (PV + HA). Functional integrity and morphological damages were then evaluated by 2‐hour oxygenated reperfusion at 37°C. HyFACS significantly lowered portal venous pressure, transaminase, and high mobility group box protein 1 release compared with vehicle‐treated controls (P < 0.01). Hyaluronic acid clearance was significantly higher in the HyFACS‐PV and ‐PV + HA groups when compared with the others (P < 0.01), demonstrating the efficacy of the PV route to maintain the sinusoidal endothelia. In contrast, bile production and lactate dehydrogenase leakage therein were both significantly improved in HyFACS‐HA and ‐PV + HA (P < 0.01), representing the superiority of the arterial route to attenuate biliary damage. Electron microscopy consistently revealed that sinusoidal ultrastructures were well maintained by portal HyFACS, while microvilli in bile canaliculi were well preserved by arterial flush. As an underlying mechanism, HyFACS significantly lowered oxidative damages, thus improving the glutathione/glutathione disulfide ratio in liver tissue. In conclusion, HyFACS significantly protected liver grafts from IRI by ameliorating oxidative damage upon reperfusion in the characteristic manner with its route of administration. Given its safety, simplicity, and cost‐effectiveness, end‐ischemic HyFACS may be a novel pretransplant conditioning for cold‐stored donor organs.

Coexistence of Bilirubin ≥10 mg/dl and Prothrombin Time-international Normalized Ratio ≥1.6 on Day 7: A Strong Predictor of Early Graft Loss After Living Donor Liver Transplantation

Background Early allograft dysfunction (EAD) defined by serum total bilirubin (TB) of 10 mg/dL or greater or prothrombin time-international normalized ratio (PT-INR) of 1.6 or greater on postoperative day 7 (POD 7) or aminotransferase greater than 2000 IU/L within the first week, is associated with early graft loss after deceased-donor liver transplantation. We aimed to determine the prognostic impact of the EAD definition in living-donor liver transplantation (LDLT). Methods We analyzed the validity of the EAD definition and its impact on early graft survival in 260 adult recipients who underwent primary LDLT. Results Eighty-four (32.3%) patients met the EAD criteria; 59 (22.7%) and 46 (17.7%) patients had TB of 10 mg/dL or greater and PT-INR of 1.6 or greater on POD 7, respectively, and 22 (8.5%) patients satisfied both criteria. Graft survival differed significantly when stratified according to TB of 10 mg/dL or greater and PT-INR of 1.6 or greater (P < 0.0001). PT-INR of 1.6 or greater resulted in higher graft mortality (risk ratio [RR], 3.87; P < 0.0001 at 90 days; RR, 2.97; P < 0.0001 at 180 days), as did TB of 10 mg/dL or greater (RR, 1.89; P = 0.027 at 90 days; RR, 1.91; P = 0.006 at 180 days). Coexistence of TB of 10 mg/dL or greater and PT-INR of 1.6 or greater was strongly associated with early graft loss (59.1%, RR, 6.97 at 90 days; 68.2%; RR, 5.75 at 180 days). In Cox regression analysis, PT-INR of 1.6 or greater and TB of 10 mg/dL or greater on POD 7 were significant risk factors for early graft loss (hazard ratio, 4.10; 95% confidence interval, 2.35-7.18; P < 0.0001, and hazard ratio, 2.43; 95% confidence interval, 1.39-4.24; P = 0.0018, respectively). Conclusions TB of 10 mg/dL or greater and/or PT-INR of 1.6 or greater on POD 7 predicted early graft loss after LDLT, and their coexistence worsened patient outcomes.

Reply to “Representing Subnormothermic Machine Perfusion in Fatty Livers: The Complete Picture?”

We demonstrated that subnormothermic machine perfusion (SMP) successfully protected 50–60% macrosteatotic livers from preservation–reperfusion injury compared with the gold standard method, cold storage (CS) (2). Vairetti et al also reported on the efficacy of SMP in preserving steatotic livers (3). In both studies, the use of SMP resulted in significantly less hepatocellular damage, increased bile production, reduced portal-venous perfusion pressure, and less oxidative damage than was demonstrated with the use of CS. Indeed, both studies used steatotic rat livers, assessed graft viability by using an ex vivo reperfusion setting, and demonstrated seemingly similar protective effects provided by SMP. However, there are several differences between the two studies.

Contents Vol. 53, 2014

I. Alwayn, Halifax D.K. Bartsch, Marburg C. Bassi, Verona W.O. Bechstein, Frankfurt am Main J.A. Bradley, Cambridge M. Cikirikcioglu, Geneva P.-A. Clavien, Zurich R.W.F. de Bruin, Rotterdam C. Eipel, Rostock S. Fichtner-Feigl, Regensburg H. Friess, Munich G. Galata, London D.J. Gouma, Hilversum J.K. Habermann, Lübeck M. Heberer, Basel M. Heger, Amsterdam T. Hubert, Lille W.R. Jarnagin, New York, N.Y. J.C. Kalff, Bonn M.W. Laschke, Homburg/Saar H.-A. Lehr, Lausanne C.M. Malata, Cambridge T. Minor, Bonn M. Morino, Torino J. Pirenne, Leuven A. Schachtrupp, Melsungen R. Schramm, Munich L. Steinstraesser, Bochum A. Szijártó, Budapest R.H. Tolba, Aachen T.M. van Gulik, Amsterdam M.A. Venermo, Helsinki D.C. Winter, Dublin Y. Yamamoto, Akita Clinical and Experimental Surgery