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Background/purpose: This experimental study in rats aimed to investigate the impact of very early introduction (within 3 h) of everolimus (EVR) + reduced-tacrolimus (TAC) after partial liver transplantation (LT) on liver regeneration, rejection, and survival., Methods: Based on appropriate dose of EVR + reduced-TAC in 70% hepatectomy (Experiment 1), allogeneic 30% partial LT (Experiment 2) and whole LT (Experiment 3) were performed., Results: After partial LT in EVR + reduced-TAC therapy, restoration of liver graft weight (to that of the whole liver) was delayed compared with standard dose TAC monotherapy (standard-TAC) on day 3 (59.3% vs. 72.9%; p < .001) and 14 (88.1% vs. 95.5%; p = .01). Survival was 75%, which was not as high as the value of 100% observed for standard-TAC, because neither infection nor rejection could be prevented. By contrast, survival after whole LT was 100% as neither infection nor rejection occurred., Conclusions: The very early introduction of EVR + reduced-TAC after partial LT delayed liver regeneration, and made it difficult to manage the dose required to suppress both infection and rejection. On the other hand, EVR + reduced-TAC could be introduced safely very early after whole LT., (© 2023 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Background/purpose: This prospective study aimed to investigate the dynamic changes in the gut microbiota (GM) and associated intestinal environment, which were assessed by measuring fecal organic acid (OA) concentrations, during the early period after liver transplantation (LT). To understand the fundamental characteristics of the human GM, data obtained from living donors were also analyzed., Methods: Fixed-point observation was performed in 23 recipients and 21 donors for up to 2 weeks after LT. The GM and OA concentrations were investigated using ribosomal RNA-targeted reverse-transcription quantitative polymerase chain reaction and high-performance liquid chromatography, respectively., Results: Before LT, the recipients exhibited remarkable dysbiosis and OA depletion, which were proportional to the model for end-stage liver disease score. Correlations between the abundances of some specific strains and OA concentrations were observed. After LT, while donor lobectomy caused only slight, transient and reversible changes in the GM and OA concentrations, recipients exhibited delayed recovery in these factors. However, no clear evidence of causality was observed between the GM or OA concentrations and LT outcomes., Conclusions: The GM and intestinal environment in LT recipients exhibited characteristics that were clearly different from those in donors. LT did not normalize but rather disrupted the GM during the early post-LT period, but its negative clinical impact could be minimized with perioperative management., (© 2022 Japanese Society of Hepato-Biliary-Pancreatic Surgery.)

Although rat liver transplantation (LT) is useful in training surgeons to perform microsurgery, mastering these surgical techniques remains difficult. Systematized training protocols that enable learning of the proper skills in a short period of time are needed. The present study describes an efficient five-step rat LT training protocol for surgeons designed to be mastered within 3 months through continuous training. The first step was to review all procedures by watching full videos of rat LT and to watch actual LT operations performed by a skilled surgeon, enabling recognition of the anatomy of rat abdominal organs. The second step was to perform ten donor operations, including ex vivo graft preparation, to learn the atraumatic and delicate techniques. The third step was to perform ten LTs, with the goal of achieving an anhepatic time <20 min and surviving until the next day. The fourth step was to perform ten additional LTs, with the goal of achieving 7 days of survival. The fifth step was to perform 5-10 more LTs, with the goal of achieving 7 days of survival in five consecutive LT operations. Systematizing the training was found to increase its efficiency. Furthermore, determining the specific number of operations in advance is useful to maintain motivation for training. Mastering efficient rat LT will not only enhance the success of preclinical research but will enable young surgeons to better perform vascular anastomoses under a microscope in humans., (© 2022 The Author(s). Published by S. Karger AG, Basel.)

The impact of T cell-mediated rejection (TCMR) after liver transplantation (LT) on the alterations in the gut microbiota (GM) and associated intestinal environment represented by fecal organic acids (OAs) require further elucidation. A rat allogeneic LT model was prepared without immunosuppressants or antibiotics, and a syngeneic model was used as a control. Qualitative and quantitative analyses of fecal samples at fixed time points were performed. Correlation analyses were also performed between liver function and GMs and OA levels. In the allogeneic TCMR group, the number of predominant obligate anaerobes decreased as liver function declined. Clostridioides difficile , Enterobacteriaceae , Enterococcus , Streptococcus , and Staphylococcus were significantly increased. Regarding fecal OA concentration, short-chain fatty acid (SCFA) concentrations were depleted as liver function declined. In contrast, in the syngeneic group, GM and OAs exhibited only slight, transient, and reversible disturbances. In addition, alanine aminotransferase and total bilirubin were positively correlated with the number of Enterobacteriaceae and Enterococcus, and negatively correlated with the fecal concentration of SCFAs. The allogeneic TCMR model demonstrated distinct dysbiosis and depletion of fecal OAs as TCMR progressed after LT. The degree of graft injury was closely related to the number of specific bacterial strains and the concentrations of fecal SCFAs., Competing Interests: Authors TS and TA were employed by the company Yakult Honsha Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yao, Yagi, Ogawa, Hirata, Miyachi, Iwamura, Uozumi, Sugimoto, Asahara, Uemoto and Hatano.)

Background: Ischemia and reperfusion injury is an important factor that determines graft function after liver transplantation, and oxygen plays a crucial role in this process. However, the relationship between the intraoperative high fraction of inspiratory oxygen (FiO 2 ) and living-donor-liver-transplantation (LDLT) outcome remains unclear., Patients and Methods: A total of 199 primary adult-to-adult LDLT cases in Kyoto University Hospital between January 2010 and December 2017 were enrolled in this study. The intraoperative FiO 2 was averaged using the total amount of intraoperative oxygen and air and defined as the calculated FiO 2 (cFiO 2 ). The cutoff value of cFiO 2 was set at 0.5., Results: Between the cFiO 2  <0.5 (n = 156) and ≥0.5 group (n = 43), preoperative recipients' background, donor factors, and intraoperative parameters were almost comparable. Postoperatively, the cFiO 2  ≥0.5 group showed a higher early allograft dysfunction (EAD) rate (P = 0.049) and worse overall graft survival (P = 0.036) than the cFiO 2  <0.5 group. Although the cFiO 2  ≥0.5 was not an independent risk factor for EAD in multivariable analysis (OR 2.038, 95%CI 0.992-4.186, P = 0.053), it was an independent risk factor for overall graft survival after LDLT (HR 1.897, 95%CI 1.007-3.432, P = 0.048)., Conclusion: The results of this study suggest that intraoperative high FiO 2 may be associated with worse graft survival after LDLT. Avoiding higher intraoperative FiO 2 may be beneficial for LDLT recipients., (© 2022. The Author(s) under exclusive licence to Société Internationale de Chirurgie.)

Background & Aims: Blood loss during liver transplantation (LT) is one of the major concerns of the transplant team, given the potential negative post-transplant outcomes related to it. Blood loss was reported to be higher in certain body compositions, such as obese patients, undergoing LT. Therefore, we aimed to study the risk factors for high blood loss (HBL) during adult living donor liver transplant (ALDLT) including the body composition markers; visceral-to-subcutaneous adipose tissue area ratio (VSR), skeletal muscle index and intramuscular adipose tissue content. In June 2015, an aggressive perioperative rehabilitation and nutritional therapy (APRNT) program was prescribed in our institute for the patients with abnormal body composition., Methods: We retrospectively analyzed 394 patients who had undergone their first ALDLT between 2006 and 2019. Risk factors for HBL were analyzed in the total cohort. Differences in blood loss and risk factors were analyzed in relation to the APRNT., Results: Multivariate risk factor analysis in the total cohort showed that a high VSR (odds ratio (OR): 1.98, 95% confidence interval (CI): 1.19-3.29, P = 0.009), was an independent risk factor for HBL during ALDLT, as well as a history of upper abdominal surgery, simultaneous splenectomy and the presence of a large amount of ascites. After the introduction of the APRNT, a significantly lower blood loss was observed during the ALDLT recipient operation (P = 0.003). Moreover, the significant difference in blood loss observed between normal and high VSR groups before the application of the APRNT (P < 0.001), was not observed with the APRNT (P = 0.85). Likewise, before the APRNT, only high VSR was a risk factor for HBL by multivariate analysis (OR: 2.34, CI: 1.33-4.09, P = 0.003). Whereas with the APRNT, high VSR was no longer a significant risk factor for HBL even by univariate analysis (OR: 0.89, CI: 0.26-3.12, P = 0.86)., Conclusion: Increased visceral adiposity was an independent risk factor for high intraoperative blood loss during ALDLT recipient operation. With APRNT, high VSR was not associated with high blood loss. Therefore, APRNT might have mitigated the risk of high blood loss related to high visceral adiposity., Competing Interests: Conflict of interest The authors of this manuscript have no conflict of interest to disclose., (Copyright © 2020 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

We evaluated the hypothesis that grafts from donors with high muscle mass and quality may have a better outcome after living-donor-liver-transplantation (LDLT) than those from usual donors. A total of 376 primary adult-to-adult LDLT cases were enrolled in this study. Donor skeletal muscle mass index (SMI) and intramuscular adipose tissue content (IMAC) were used as markers of muscle mass and quality. In male donor cases (n = 198), those with higher SMI and lower IMAC than age-adjusted values were defined as the "high muscularity donors" (n = 38) and the others were defined as the "control" (n = 160). The high muscularity donor showed better 1-year (97% vs 82%, P = .020) and overall graft survival rate (88% vs 67%, P = .024) than the control group after LDLT. Contrastingly, the influence of the muscularity was not observed in female donor cases. Multivariable analysis including donor age confirmed that a high muscularity donor was an independent protective factor for overall graft survival after LDLT (hazard ratio, 0.337; 95% CI: 0.101-0.838; P = .017). Our study first confirmed that high muscle mass and quality of a male donor is a protective factor of allograft loss after LDLT, independently from donor age., (© 2020 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Background: Liver transplantation in the setting of portal vein thrombosis is an intricate issue that occasionally necessitates extraordinary procedures for portal flow restoration. However, to date, there is no consensus on a persistent management strategy, particularly with extensive forms. This work aims to introduce our experience-based surgical management algorithm for portal vein thrombosis during liver transplantation and to clarify some of the debatable circumstances associated with this problematic issue., Methods: Between 2006 and 2019, 494 adults underwent liver transplantation at our institute. Ninety patients had preoperative portal vein thrombosis, and 79 patients underwent living donor liver transplantation. Our algorithm trichotomized the management plan into 3 pathways based on portal vein thrombosis grade. The surgical procedures implemented included thrombectomy, interposition vein grafts, jump grafts from the superior mesenteric vein, jump grafts from a collateral and renoportal anastomosis in 56, 13, 11, 4, and 2 patients, respectively. Four patients with mural thrombi did not require any special intervention., Results: Thirteen patients experienced posttransplant portal vein complications. They all proved to have a patent portal vein by the end of follow-up regardless of the management modality. No significant survival difference was observed between cohorts with versus without portal vein thrombosis. The early graft loss rate was significantly higher with advanced grades (P = .048) as well as technically demanding procedures (P = .032)., Conclusion: A stepwise broad-minded strategy should always be adopted when approaching advanced portal vein thrombosis during liver transplantation. An industrious preoperative evaluation should always be carried out to locate the ideal reliable source for portal flow restoration., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Liver steatosis is a leading cause of graft disposal in liver transplantation, though the degree of steatosis is often the single factor determining acceptability of the graft. We investigated how the cause of liver steatosis affects graft function in rat orthotopic liver transplantation (OLT). OLT was performed using 2 types of steatotic liver grafts: the fasting and hyperalimentation (FHA) model and the methionine- and choline-deficient diet models. The FHA and 4-week feeding of a methionine- and choline-deficient diet (MCDD4wk) groups showed similar liver triglyceride levels without signs of steatohepatitis. Therefore, the 2 groups were compared in the following experiment. With 6-hour cold storage, the 7-day survival rate after OLT was far worse in the FHA than in the MCDD4wk group (0% versus 100%, P = 0.002). With 1-hour cold storage, the FHA group showed higher aspartate aminotransferase and alanine aminotransferase levels and histological injury scores in zones 1 and 2 at 24 hours after reperfusion than the normal liver and MCDD4wk groups. Intrahepatic microcirculation and tissue adenosine triphosphate levels were significantly lower in the FHA group after reperfusion. Hepatocyte necrosis, sinusoidal endothelial cell injury, and abnormal swelling of the mitochondria were also found in the FHA group after reperfusion. Tissue malondialdehyde levels were higher in the MCDD4wk group before and after reperfusion. However, the grafts up-regulated several antioxidant enzymes soon after reperfusion. Even though the degree of steatosis was equivalent, the 2 liver steatosis models possessed quite unique basal characteristics and showed completely different responses against ischemia/reperfusion injury and survival after transplantation. Our results demonstrate that the degree of fat accumulation is not a single determinant for the usability of steatotic liver grafts., (Copyright © 2020 by the American Association for the Study of Liver Diseases.)

Background: The role of anti-human leukocyte antigen (HLA) antibodies in operational tolerance (OT) after pediatric living-donor liver transplantation (LDLT) remains inconclusive. We investigated whether the presence of HLA antibodies impeded the development of OT., Methods: We retrospectively examined the prevalence of anti-HLA antibodies in pediatric LDLT recipients before transplantation and at 3 weeks after transplantation and analyzed the significance of those antibodies in relation to later OT. Forty pediatric LDLTs were performed between April 1996 and December 2000 and followed up through July 2011, with sera available for measurement of HLA antibodies. Seventeen patients achieved OT (mean follow-up, 4571.9±544.7 days) and 23 patients did not achieve OT (mean follow-up, 4532.0±425.4 days). Protocol liver biopsy was done for 14 OT patients and 16 non-OT patients. Their sera were tested for anti-HLA class I and II antibodies using the LABScreen single antigen beads test, in which a 1000 mean fluorescence value was considered positive., Results: The prevalence of antibodies after transplantation in non-OT patients was higher than in OT patients (95.2% vs. 73.3%; P<0.001). The highest mean fluorescence intensity of antibodies was significantly higher in non-OT patients than in OT patients. The prevalence of HLA-B, HLA-C, HLA-DQ, and HLA-DR antibodies was significantly higher in non-OT patients than in OT patients. The highest mean fluorescence intensity of HLA-A, HLA-B, and HLA-DQ observed in non-OT patients was significantly higher than those in OT patients., Conclusions: In our study, posttransplantation HLA antibodies were associated with the future absence of OT. A prospective study with more patients is necessary to confirm the predictive value of HLA antibodies for OT.

We examined the prevalence of gastrointestinal bleeding in patients undergoing living-related liver transplantation (LRLT). Seventy-seven patients (37 male and 40 female) underwent LRLT at the University of Tokyo Hospital from January 1996 through December 1999. Forty-nine patients were children or adolescents and 28 patients were adults. The mean follow-up period was 21.3 +/- 12.8 months. Nine of the 77 recipients had gastrointestinal bleeding after transplantation. The incidence of posttransplant bleeding was significantly higher in adult recipients than in pediatric recipients (25% vs 4%, P < 0.05). The ratio of graft volume to standard liver volume was significantly lower in adult recipients than in pediatric recipients (41 +/- 6% vs 86 +/- 26%, P < 0.05). Portal vein thrombosis (PVT) developed after LRLT in 8 patients. Variceal bleeding subsequently occurred in all 4 adult patients with PVT but in only 1 of 4 pediatric patients. Small-for-size grafts may cause transient portal hypertension, which increases the risk of gastrointestinal bleeding.

One hundred fourteen living-donor liver transplants were performed at Tokyo University hospital from 1996-2000, including 66 children and 48 adults. Most (86%) of the children were transplanted for biliary atresia, whereas adults were more often transplanted for primary biliary cirrhosis (40%) or liver cirrhosis (23%) due to hepatitis or other unknown causes. Among children, 52% received the left lobe lateral segment, 23% an extended lateral segment and 21% the left lobe. The graft volume to standard liver ratio averaged 84%. Among adults, 79% received a left lobe; however, we have used the right lobe for most recent cases (21%) to provide sufficient volume. Parents donated to the pediatric recipients about 95% of the time, but a variety of family members donated for the adult transplants. The actual overall 3- and 5-year patient survival rates were 88.6% and 87.7%, respectively, and were slightly higher in children than adults. The results are comparable to those achieved with cadaver livers.

We describe a case of reversible hepatofugal portal flow 1 week after transplantation of a small-for-size liver graft from a living donor. A transient increase in intrahepatic portal vascular resistance was the suspected cause. The portal venous flow normalized after residual collateral channels had been interrupted surgically. The patient was discharged on the 90th postoperative day. Liver transplant clinicians should be aware that hepatofugal flow can occur with small-for-size liver grafts, despite sufficient portal venous flow immediately after transplantation.

Background: In living-related liver transplantation (LRLT) in small children, standard end-to-end portal vein (PV) anastomosis is usually difficult because of a inadequate total PV length, or because of a size mismatch between the graft and the recipient PV. In this report, we present our new portal venoplasty technique for the recipient PV., Methods: After dissection of the recipient PV, the wall between the right and left branches of the PV is severed longitudinally as in the branch patch technique. The anterior and posterior edges of both branches are joined using running sutures, to form a longer and wider PV for anastomosis., Results: This new portal venoplasty technique was used in 7 of 28 child cases, and gave good results without thrombosis or other complications., Conclusions: Our new portal venoplasty technique is useful in LRLT in small children when the recipient or graft PV is not long enough.

We monitored the serial changes of natural killer cell (NK) activity in eight recipients of living-related liver transplantation. The HLA types of all eight patients were haplotypically identical with those of their donors. Tacrolimus and methylprednisolone were used for immunosuppression. The NK activity before transplantation was 24.1 +/- 20.2% which is surprisingly low when compared with the value for normal individuals (67.7 +/- 13.2%, P < 0.01) or a liver dysfunction group (49.4 +/- 21.9%, P < 0.05). Serial changes in NK activity revealed a minimum of 6.1 +/- 3.6% 1 week after transplantation, gradually increasing to 49.2 +/- 12.5% at 2 months after transplantation. These results suggest that the diseased liver might play an important role in the suppression of NK activity.

A bile duct stricture caused by an inadvertent ligation or suture during donor operation is rare, but not a negligible complication after living-related liver transplantation (LRLT). We present here a simple technique to prevent this kind of complication. Before bilioenteric anastomosis, a rod-shaped surgical probe was introduced into the bile ducts of the graft to examine their patency. The position of the surgical probe and the liver segment in which the probe proceeded was checked using ultrasonography. Using this technique in all of our 60 cases of LRLT, we have had no experience of this bile duct complication. We recommend this technique to be adopted in LRLT and split-liver transplantation to diminish the risk of biliary complications.