Waiting list mortality for pediatric deceased donor liver transplantation in a Japanese living-donor-dominant program

Efficiency of machine perfusion in pediatric liver transplantation

Liver transplantation is the only life-saving procedure for children with end-stage liver disease. The field is however heterogenic with various graft types, recipient age, weight, and underlying diseases. Despite recently improved overall outcomes and the expanded use of living donors, waiting list mortality remains unacceptable, particularly in small children and infants. Based on the known negative effects of elevated donor age, higher body mass index, and prolonged cold ischemia time, the number of available donors for pediatric recipients is limited. Machine perfusion has regained significant interest in the adult liver transplant population during the last decade. Ten randomized controlled trials are published with an overall advantage of machine perfusion techniques over cold storage regarding postoperative outcomes, including graft survival. The concept of hypothermic oxygenated perfusion (HOPE) was the first and only perfusion technique used for pediatric liver transplantation today. In 2018 the first pediatric candidate received a full-size graft donated after circulatory death with cold storage and HOPE, followed by a few split liver transplants after HOPE with an overall limited case number until today. One series of split procedures during HOPE was recently presented by colleagues from France with excellent results, reduced complications, and better graft survival. Such early experience paves the way for more systematic use of machine perfusion techniques for different graft types for pediatric recipients. Clinical reports of pediatric liver transplants with other perfusion techniques are awaited. Strong collaborative efforts are needed to explore the effect of perfusion techniques in this vulnerable population impacting not only the immediate posttransplant outcome but the development and success of an entire life.

Bile acid profiles in adult patients with biliary atresia who achieve native liver survival after portoenterostomy

Bile acids have received increasing attention as a marker of the long-term prognosis and a potential therapeutic target in patients with biliary atresia, which is a progressive disease of the hepatobiliary system. A detailed analysis of serum and urinary bile acid compositions was conducted to assess the characteristics of bile acid profiles and the correlation between bile acid profiles and liver fibrosis markers in adult patients with biliary atresia who achieved bilirubin normalization. Serum total bile acids and glucuronide-conjugated (glyco- and tauro-) cholic acids (GCA and TCA) and chenodeoxycholic acids (GCDCA and TCDCA) were significantly higher in patients with biliary atresia than in healthy controls, whereas unconjugated CA and CDCA showed no significant difference. There were no significant differences in CA to CDCA ratios and glycine-to-taurine-conjugated ratios. Urinary glycocholic acid 3-sulfate (GCA-3S) was significantly higher in patients with biliary atresia. Serum GCDCA showed a strong positive correlation with Mac-2 binding protein glycosylation isomer (M2BPGi). These results demonstrate that bile acid congestion persists into adulthood in patients with biliary atresia, even after cholestasis has completely improved after Kasai portoenterostomy. These fundamental data on bile acid profiles also suggest the potential value of investigating bile acid profiles in patients with biliary atresia.

Drug metabolic activity as a selection factor for pluripotent stem cell-derived hepatic progenitor cells

As a metabolic organ, the liver plays a variety of roles, including detoxification. It has been difficult to obtain stable supplies of hepatocytes for transplantation and for accurate hepatotoxicity determination in drug discovery research. Human pluripotent stem cells, capable of unlimited self-renewal, may be a promising source of hepatocytes. In order to develop a stable supply of embryonic stem cell (ESC)-derived hepatocytes, we have purified human ESC-derived hepatic progenitor cells with exposure to cytocidal puromycin by using their ability to metabolize drugs. Hepatic progenitor cells stably proliferated at least 220-fold over 120 days, maintaining hepatic progenitor cell-like properties. High drug-metabolizing hepatic progenitor cells can be matured into liver cells by suppressing hepatic proliferative signals. The method we developed enables the isolation and proliferation of functional hepatic progenitors from human ESCs, thereby providing a stable supply of high-quality cell resources at high efficiency. Cells produced by this method may facilitate cell therapy for hepatic diseases and reliable drug discovery research.

Japanese national survey on declined liver allografts from brain-dead donors: High decline rate but promising outcomes in allografts with moderate steatosis

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.

Evaluation of living donors for hereditary liver disease (siblings, heterozygotes)

Living donor liver transplantation (LDLT) is recognised as an alternative treatment modality to reduce waiting list mortality and expand the donor pool. Over recent decades, there have been an increasing number of reports on the use of LT and specifically LDLT for familial hereditary liver diseases. There are marginal indications and contraindications that should be considered for a living donor in paediatric parental LDLT. No mortality or morbidity related to recurrence of metabolic diseases has been observed with heterozygous donors, except for certain relevant cases, such as ornithine transcarbamylase deficiency, protein C deficiency, hypercholesterolemia, protoporphyria, and Alagille syndrome, while donor human leukocyte antigen homozygosity also poses a risk. It is not always essential to perform preoperative genetic assays for possible heterozygous carriers; however, genetic and enzymatic assays must hereafter be included in the parental donor selection criteria in the aforementioned circumstances.

Marginal parental donors for pediatric living donor liver transplantation

PURPOSE OF REVIEW

Living donor liver transplantation (LT) has been increasingly recognized as an effective treatment modality with excellent patient survival. Indications for LT have evolved not only for cholestatic liver disease, but also metabolic liver diseases. Living donor selection, particularly for pediatric inherited disease, is essential to prevent morbidity, both in the donor and recipient.

RECENT FINDINGS

Based on 30 years of experience in pediatric living donor LT in Japan, we could identify marginal parental living donors who have potential risks following LT, including heterozygous mothers with ornithine transcarbamylase deficiency, heterozygous protein C deficiency, heterozygous hypercholesterolemia, heterozygous protoporphyria, asymptomatic parental donors with paucity of intrahepatic bile duct, and human leukocyte antigen-homozygous parental donors.

SUMMARY

Although these situations seem rare due to infrequency of the condition, careful living donor evaluation is required to optimize the outcomes for pediatric recipients. In the setting of an appropriate selection of a living donor, we should avoid any additional hazards, given that the procedure itself has risks for a healthy individual.

Development of a risk score model for 1‐year graft loss after adult deceased donor liver transplantation in Japan based on a 20‐year nationwide cohort

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.

Long-term Outcomes of Pediatric Living Versus Deceased Donor Liver Transplantation Recipients: A Systematic Review and Meta-analysis

Living donor liver transplantation (LDLT) emerged in the 1980s as a viable alternative to scarce cadaveric organs for pediatric patients. However, pediatric waitlist mortality remains high. Long-term outcomes of living and deceased donor liver transplantation (DDLT) are inconsistently described in the literature. Our aim was to systematically review the safety and efficacy of LDLT after 1 year of transplantation among pediatric patients with all causes of liver failure. We searched the MEDLINE, Medline-in-Process, MEDLINE Epub Ahead of Print, Embase + Embase Classic (OvidSP), and Cochrane (Wiley) from February 1, 1947 to February 26, 2020, without language restrictions. The primary outcomes were patient and graft survival beyond 1 year following transplantation. A meta-analysis of unadjusted and adjusted odds and hazard ratios was performed using a random-effects model. A total of 24 studies with 3677 patients who underwent LDLT and 9098 patients who underwent DDLT were included for analysis. In patients with chronic or combined chronic liver failure and acute liver failure (ALF), 1-year (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.53-0.88), 3-year (OR, 0.73; 95% CI, 0.61-0.89), 5-year (OR, 0.71; 95% CI, 0.57-0.89), and 10-year (OR, 0.42; 95% CI, 0.18-1.00) patient and 1-year (OR, 0.50; 95% CI, 0.35-0.70), 3-year (OR, 0.55; 95% CI, 0.37-0.83), 5-year (OR, 0.5; 95% CI, 0.32-0.76), and 10-year (OR, 0.26; 95% CI, 0.14-0.49) graft survival were consistently better in LDLT recipients compared with those in DDLT recipients. In patients with ALF, no difference was seen between the 2 groups except for 5-year patient survival (OR, 0.60; 95% CI, 0.38-0.95), which favored LDLT. Sensitivity analysis by era showed improved survival in the most recent cohort of patients, consistent with the well-described learning curve for the LDLT technique. LDLT provides superior patient and graft survival outcomes relative to DDLT in pediatric patients with chronic liver failure and ALF. More resources may be needed to develop infrastructures and health care systems to support living liver donation.

Outcomes of Pediatric Liver Transplantation in Japan: A Report from the Registry of the Japanese Liver Transplantation Society (JLTS)

BACKGROUND

The Japanese Liver Transplantation Society (JLTS), a cooperative research consortium, was established in 1980 in order to characterize and follow trends in patient characteristics and graft survival among all liver transplant patients in Japan. This study analyzed factors that may affect the current outcomes of pediatric patients who undergo LT by evaluating one of the largest pediatric LT cohorts in the world.

METHODS

Between November 1989 and December 2018, 3347 pediatric patients underwent LT in Japan. The survival outcomes of each donor and recipient variant were evaluated.

RESULTS

The procedures performed during the study period included living donor LT (LDLT; n=3271), deceased donor LT (DDLT; n=69), and domino LT (n=7). There were 1510 male (45.1%) and 1837 female (54.9%) recipients with a median age of 1.7 years (range: 9 days to17.9 years). The graft survival rates at 1, 10, 20, and 30 years were 88.9%, 82.2%, 77.1%, and 75.4%, respectively. Donor age, donor BMI, blood type incompatibility, recipient age, etiology of liver disease, transplant type, center experience, and transplant era were found to be significant predictors of overall graft survival. LDLT is a major treatment modality for end-stage liver disease in children; DDLT and domino LT were applied as alternative treatments for LDLT in patients with specific pediatric liver diseases that are considered to have a poor prognosis following LDLT.

CONCLUSIONS

Satisfactory long-term pediatric patient survival outcomes were achieved in the JLTS series, and we should continue to promote the deceased donor organ transplantation program in Japan.

Current status of pediatric deceased donor liver transplantation: Lessons learned from a high-volume center in Japan where living donation remains predominant

BACKGROUND

In Japan, a recent gradual increase in deceased donor donation has expanded opportunities for pediatric patients to obtain deceased grafts.

METHODS

Forty-three children underwent deceased donor liver transplantation (DDLT) at our institute before February 2020. Twenty-five patients received a split or reduced graft and 18 patients received a whole graft. The clinical outcomes of DDLT were retrospectively analyzed.

RESULTS

The main organ resource was split/reduced grafts retrieved from adult donors; however, the number of whole grafts retrieved from pediatric donors has increased. The rates of major complications were similar in the two groups. The 5-year graft survival rate of patients who received a split/reduced graft (78.0%) was lower than that of patients who received a whole graft (88.9%; P = .40). The 3-year graft survival rates of patients who recently received a split/reduced graft and a whole graft improved to 92.3% and 91.7%, respectively.

CONCLUSIONS

The recent amendment of the organ allocation system, especially the introduction of pediatric prioritization, can effectively increase the chance to obtain deceased donor grafts for pediatric DDLT in Japan. The recent refinements in donor and recipient selection and in the surgical technique of split DDLT can improve the outcomes of pediatric DDLT in Japan.