Koji Umeshita's research while affiliated with Hiroshima University and other places

Objective To analyze 10,000 cases of living donor liver transplantation (LDLT) recipient data to elucidate outcomes with special reference to the graft-versus-recipient weight ratio (GRWR), based on the Japanese Liver Transplantation Society (JLTS) registry. Background The JLTS registry has been accurate and complete in characterizing and following trends in patient characteristics and survival of all patients with LDLT. Methods Between November 1989 and August 2021, 10,000 patients underwent LDLT in Japan. The procedures performed during the study period included pediatric liver transplantation (age <18 years, n = 3572) and adult liver transplantation (age ≥18 years, n=6428). Factors related to patient survival (PS) and graft survival (GS) were also analyzed. Results The GRWR was <0.7, 0.7 to <0.8, 0.8 to <3, 3 to <5, and ≥5 in 0.2%, 2.0%, 61.8%, 31.8%, and 2.6% of pediatric patients and <0.6, 0.6 to <0.7, 0.7 to <0.8, and ≥0.8 in 8.0%, 12.7%, 17.7%, and 61.5% of adult patients, respectively. Among pediatric recipients, the PS rate up to 5 years was significantly better in cases with a GRWR ≤5 than in those with a GRWR >5. When the GRWR and donor age were combined, among adult recipients 50 to 60 years old, the early PS and GS up to 5 years were significantly better in cases with a GRWR ≥0.7, than in those with a GRWR <0.7. ( P = 0.02). In adults, a multivariate analysis showed that GRWR <0.6, transplant era (<2011), donor age (>60 years), recipient age (>60 years), model for end-stage liver disease score (≥20), and center volume (<10) were significant prognostic factors for long-term PS. Conclusion Although a satisfactory long-term PS and GS, especially in the recent era (2011-2021), was achieved in the JLTS series, a GRWR ≥5 in pediatric cases and relatively old donors with a GRWR <0.7 in adult cases should be managed with caution.

Aim: Liver allografts from brain-dead donors, which were declined and were eventually not transplanted due to accompanying marginal factors, have never been surveyed in Japan. We surveyed the declined allografts and discussed the graft potential focusing on various marginal factors. Methods: We collected data on brain-dead donors between 1999 and 2019 from the Japan Organ Transplant Network. We divided their liver allografts into declined (nontransplanted) and transplanted ones, and then characterized declined ones focusing on their timepoints of decline and accompanying marginal factors. For each marginal factor, we calculated the decline rate from the number of declined and transplanted allografts, and assessed the 1-year graft survival rate from transplanted allografts. Results: A total of 571 liver allografts were divided into 84 (14.7%) declined and 487 (85.3%) transplanted ones. In the declined allografts, a majority was declined after laparotomy (n = 55, 65.5%), most of which had steatosis and/or fibrosis (n = 52). Out of the moderate steatotic (without F ≥ 2 fibrosis) allografts (n = 33), 21 were declined and 12 were transplanted, leading to a 63.6% decline rate. The latter 12 achieved a 92.9% 1-year graft survival rate after transplantation. Comparison of donor background showed no significant difference between the declined and transplanted allografts. Conclusion: Pathological abnormalities of steatosis/fibrosis seem to be the most common donor factor leading to graft decline in Japan. Allografts with moderate steatosis were highly declined; however, transplanted ones achieved promising outcomes. This national survey highlights the potential utility of liver allografts with moderate steatosis.

In developing a formula for manual use in clinical settings, simplicity is as important as accuracy. Whole-liver (WL) mass is often estimated using demographic and anthropometric information to calculate the standard liver volume or recommended graft volume in liver transplantation. Multiple formulas for estimating WL mass have been reported, including those with multiple independent variables. However, it is unknown whether multivariable models lead to clinically meaningful improvements in accuracy over univariable models. Our goal was to quantitatively define clinically meaningful improvements in accuracy, which justifies an additional independent variable, and to identify an estimation formula for WL graft weight that best balances accuracy and simplicity given the criterion. From the Japanese Liver Transplantation Society registry, which contains data on all liver transplant cases in Japan, 129 WL donor-graft pairs were extracted. Among the candidate models, those with the smallest cross-validation (CV) root-mean-square error (RMSE) were selected, penalizing model complexity by requiring more complex models to yield a ≥5% decrease in CV RMSE. The winning model by voting with random subsets was fitted to the entire dataset to obtain the final formula. External validity was assessed using CV. A simple univariable linear regression formula using body weight (BW) was obtained as follows: WL graft weight [g] = 14.8 × BW [kg] + 439.2. The CV RMSE (g) and coefficient of determination (R2) were 195.2 and 0.548, respectively. In summary, in the development of a simple formula for manually estimating WL weight using demographic and anthropometric variables, a clinically acceptable trade-off between accuracy and simplicity was quantitatively defined, and the best model was selected using this criterion. A univariable linear model using BW achieved a clinically optimal balance between simplicity and accuracy, while one using body surface area performed similarly.

Background Combined hepatocellular and cholangiocarcinoma is a rare primary liver cancer with histological features of both hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Little is known about the prognostic features and molecular mechanism of cHCC-iCCA. Acylphosphatase 1 is a cytosolic enzyme that produces acetic acid from acetyl phosphate and plays an important role in cancer progression. Aims We evaluated the clinical significance of ACYP1 expression in cHCC-iCCA, HCC, and iCCA. Methods ACYP1 immunohistochemistry was performed in 39 cases diagnosed with cHCC-iCCA. The prognosis was evaluated in three different cohorts (cHCC-iCCA, HCC, and iCCA). The relationships between ACYP1 expression and cell viability, migration, invasiveness, and apoptosis were examined using siRNA methods in vitro. In vivo subcutaneous tumor volumes and cell apoptosis were evaluated after downregulation of ACYP1 expression. Results Almost half of the patients with cHCC-iCCA were diagnosed with high ACYP1 expression. In all three cohorts, the cases with high ACYP1 expression had significantly lower overall survival, and high ACYP1 expression was identified as an independent prognostic factor. Downregulation of ACYP1 reduced the proliferative capacity, migration, and invasiveness of both HCC and iCCA cells. Moreover, knockdown of ACYP1 increased the ratio of apoptotic cells and decreased the expression of anti-apoptosis proteins. In vivo tumor growth was significantly inhibited by the transfection of ACYP1 siRNA, and the number of apoptotic cells increased. Conclusion High ACYP1 expression could influence the prognosis of cHCC-iCCA, HCC, and iCCA patients. In vitro ACYP1 expression influences the tumor growth and cell viability in both HCC and iCCA by regulating anti-apoptosis proteins.

Background: Following liver transplantation (LT), allograft liver failure can be developed by various causes and requires re-LT. Hence, this study aimed to clarify the characteristics and prognostic factors of patients with allograft liver failure awaiting deceased donor LT (DDLT) in Japan. Methods: Of the 2686 DDLT candidates in Japan between 2007 and 2016, 192 adult patients listed for re-LT were retrospectively enrolled in this study. Factors associated with waitlist mortality were assessed using the Cox proportional hazards model. The transplant-free survival probabilities were evaluated using the Kaplan-Meier analysis and log-rank test. Results: The median period from the previous LT to listing for re-LT was 1548 days (range, 4-8449 days). Primary sclerosing cholangitis (PSC), which was a primary indication, showed a higher listing probability for re-LT as compared with other primary etiologies. Recurrent liver disease was a leading cause of allograft failure and was more frequently observed in the primary indication of hepatitis C virus (HCV) infection and PSC in contrast with other etiologies. Multivariate analysis identified the following independent risk factors associated with waitlist mortality: age, Child-Turcotte-Pugh (CTP) score, mode for end-stage liver disease (MELD) score, alanine aminotransferase (ALT), and causes of allograft failure. Conclusions: Recurrent HCV and PSC were major causes of allograft liver failure in Japan. In addition to CTP and MELD scores, either serum ALT levels or causes of allograft failure should be considered as graft liver allocation measures.

Aim: Using nationwide data collected over the past 20 years, we aimed to investigate deceased donor liver transplantation (DDLT) outcomes to develop a unique risk model that can be used to establish a standard for organ acceptance in Japan. Methods: Data were collected for 449 recipients aged ≥18 years who underwent DDLT between 1999 and 2019. Least absolute shrinkage and selection operator (LASSO) regression analysis was utilized to develop an original risk score model for 1-year graft loss (termed the Japan Risk Index [JRI]). We developed risk indices according to recipient, donor, and surgery components (termed JRI-R, D, and S, respectively). The JRI was validated via a 5-fold cross-validation. We also compared DDLT outcomes and risk indices among Era1 (-2011), Era2 (-2015), and Era3 (-2019). Results: The 1-year graft survival rate was 89.5% and improved significantly, reaching 84.7%, 87.6%, and 93.9% in Era1, Era2, and Era3, respectively. The JRI was calculated as JRI-R (re-transplantation, Model for End-Stage Liver Disease score, medical condition in intensive care unit) × JRI-D (age, catecholamine index, maximum sodium, maximum total bilirubin) × JRI-S (total ischemic time) × 0.84. The risk model achieved a mean C-statistic value of 0.81 in the validation analysis. The risk index was significantly lower in Era3 than in Era2. Conclusion: Changes in the risk index over time indicated that avoiding risks contributed to the improved outcomes in Era3. The JRI is unique to adult DDLT in Japan and may be useful as a reference for organ acceptance in the future.

Purpose In recent years, the increasing number of obese individuals in Japan has made transplant teams sometimes forced to select candidates with a high body mass index (BMI) as marginal donors in living donor liver transplantation. However, data are lacking regarding the impact of a high BMI on the outcome for liver donors, particularly over the long term. Here, we aimed to clarify the impact of a high BMI on postoperative short- and long-term outcomes in liver donors. Methods We selected 80 cases that had complete 5-year data available from hepatectomies performed in 2005 to 2015 in our institute. We divided donors into overweight (BMI ≥ 25 kg/m², n = 16) and normal-weight (BMI < 25, n = 64) groups. Results Preoperatively, the overweight group had significantly higher preoperative levels of serum alanine aminotransferase and γ-glutamyl transpeptidase and a larger liver volume than the normal-weight group. Although the overweight group had significantly greater intraoperative blood loss (660 ± 455 vs 312 ± 268 mL, P = .0018) and longer operation times (463 ± 88 vs 386 ± 79 min, P = .0013), the groups showed similar frequencies of postoperative complications. At 1 year post hepatectomy, liver regeneration and spleen enlargement ratios did not significantly differ between the 2 groups. Remarkably, the overweight group showed significantly higher serum γ-glutamyl transpeptidase levels over the long term. Conclusions Overweight status alone was not a risk factor for either short- or long-term postoperative outcomes after a donor hepatectomy. However, donors with elevated γ-glutamyl transpeptidase levels, which was frequent among overweight donors, may require special attention.

Background/purpose: We aimed to verify a recent theory that female donors reduced the risk of hepatocellular carcinoma (HCC) recurrence after liver transplantation (LT). Methods: We evaluated 1,118 recipients for HCC registered in the Japanese Liver Transplantation Society database, of whom 446 received a graft from female donors (F-D group) and 672 from male donors (M-D group). Results: Between the groups, donor age, recipient age and sex, positivity of hepatitis viruses, and graft type were different, whereas tumor-related factors were all comparable. The 5-year overall recurrence rates were 14% and 16% in the F-D and M-D groups, respectively (P = 0.59). The 5-year graft recurrence rate was also comparable between the groups (4% and 6%, respectively, P = 0.17). Neither univariate nor multivariate analysis identified donor sex as a significant risk factor for recurrence. Propensity score matching showed similar 5-year overall recurrence rates (15% in the F-D group and 14% in the M-D group, P = 0.63) and graft recurrence rates (5% and 5%, respectively, P = 0.94) between the groups. Conclusion: Donor sex did not affect post-LT recurrence of HCC in the Japanese cohort and should not be considered in the process of donor selection or organ allocation.

We retrospectively reviewed 220 living liver donors, with a focus on the development of postoperative fatty liver. Data regarding demographics, comorbidities, imaging tests, operations, and biopsies were obtained from medical records. We used unenhanced CT and USG to diagnose fatty liver. Donor candidates with fatty liver underwent weight loss intervention until imaging tests no longer demonstrated any features of fatty liver. Among 220 donors, 61 were diagnosed with preoperative fatty liver. The mean BMI of these 61 donors significantly decreased from 24.9 at the first visit to 23.6 kg/m2 immediately before surgery (p=0.0386). A multivariate analysis revealed the following significant risk factors for postoperative fatty liver: male sex (p=0.0033), BMI immediately before surgery (p=0.0028), and a history of treatment for preoperative fatty liver (p=0.0231). Postoperative fatty liver was often refractory to weight loss intervention. No improvement was observed in 14 of the 32 donors who had been diagnosed with fatty liver postoperatively, and 1 of the 14 donors even developed NASH. In conclusion, special attention should be paid to prevent fatty liver after surgery in male donors who show a high BMI immediately before surgery and with a history of treatment for preoperative fatty liver, and lifelong follow‐up is recommended.