Expanding the donor pool for liver transplantation with marginal donors

Lachnospiraceae-bacterium alleviates ischemia-reperfusion injury in steatotic donor liver by inhibiting ferroptosis via the Foxo3-Alox15 signaling pathway

Ischemia-reperfusion injury (IRI) is a major obstacle in liver transplantation, especially with steatotic donor livers. Dysbiosis of the gut microbiota has been implicated in modulating IRI, and Lachnospiraceae plays a pivotal role in regulating host inflammatory and immune responses, but its specific role in liver transplantation IRI remains unclear. This study explores whether Lachnospiraceae can mitigate IRI and its underlying mechanisms. We found Lachnospiraceae-bacterium (Lachn.) abundance was significantly reduced in rats with liver cirrhosis. Lachn.-treated rats exhibited improved intestinal permeability, reduced IRI severity in both normal and steatotic donor livers, and decreased levels of neutrophil and macrophage infiltration, and inflammatory cytokines. Multi-omics analysis revealed elevated pyruvate levels in transplanted livers after Lachn. treatment, alongside reduced Alox15 and Foxo3 expression. Mechanistically, Lachn.-derived pyruvate inhibited Alox15 expression and reduced ferroptosis in normal and steatotic donor livers. Furthermore, reduced nuclear translocation of Foxo3 further suppressed Alox15 expression, alleviating IRI, especially in steatotic donor livers. Clinical samples confirmed reduced donor livers IRI in cirrhotic recipients with high Lachn. abundance after liver transplantation. In conclusion, Lachn. alleviates IRI in steatotic donor liver transplantation by inhibiting ferroptosis via the Foxo3-Alox15 axis, providing a potential therapeutic strategy to modulate gut microbiota to alleviate IRI following liver transplantation.

Introducing hyperspectral imaging as a novel tool for assessing donor liver quality during machine perfusion: A case report

BACKGROUND

Hyperspectral imaging (HSI) offers useful information on organ quality and has already been successfully used in kidney and liver transplantation to assess transplanted organs. Up to now, there is no case report in the literature describing HSI for quality assessment of a machine perfused donor liver. The allocated liver from a 49-year-old female donor (161 cm, 70 kg) was perfused with the OrganOx^® normothermic machine perfusion system in the recommended way. Organ quality assessment was performed based on laboratory values at defined time points. In addition, the final evaluation of the liver comprised macroscopic findings and HSI of each liver segment. After discarding the organ, biopsies were taken from each segment and correlated with the results of the HSI.

CASE SUMMARY

The donor liver’s size (29 cm × 17 cm × 11 cm) and weight of 2180 g posed challenges for adequate placement within the organ container. Baseline biopsy of the liver revealed no evidence of fibrosis, steatosis or inflammation. An hour after perfusion start, measurements of the perfusate indicated a pH of 7.18, a glucose level of 404 mg/dL, and a lactate level of 1.7 mmol/L. Throughout perfusion, a significant decline in glucose levels began at the fourth hour, reaching a nadir of 20 mg/dL after eight hours. Concurrently, lactate levels steadily rose, peaking at 4.9 mmol/L after the total perfusion time of 12 hours. Macroscopic alterations (signs of congestion and reduced blood circulation) on the liver’s surface were noted, particularly pronounced in segments 2, 3, and 8. HSI of these areas unveiled significant reduced oxygenation. Consequently, based on all these observations, the decision was made to discard the organ. Histological examination of the altered regions revealed congestion, necrotic changes, and dissociation of sinusoidal lining cells from liver cell cords. The histological findings correlated well with the HSI.

CONCLUSION

This case report describes the integration of HSI in the decision making of the decline of a 49-year-old machine perfused donor liver. HSI offered useful information concerning the tissue morphology and graft viability and could therefore be a useful additional tool in assessing donor liver quality before transplantation.

Elderly Ages in Liver Transplantation: Are Older Donors Really Higher Risk?

Background

There is currently a supply and demand mismatch in liver transplantation, with more patients needing transplants than grafts available. The use of older donors is one potential way of expanding access to viable grafts. No national study has yet reported on outcomes of liver transplants with donors ≥70 y.

Methods

The US Scientific Registry of Transplant Recipients registry was queried for deceased donor LT (1988-2021). Balance-of-risk (BAR) score was calculated for each patient. The primary outcome was graft survival. Cubic spline curves were used to evaluate the full spectrum of donor ages.

Results

A total of 148 960 livers met inclusion criteria: 5414 (3.6%) from donors ≥70 y and 4291 (2.9%) recipients ≥70 y. Within the overall cohort, graft survival decreased with increased donor and recipient age. Median graft survival within donors ≥70 y improved over time from 2.2 y (interquartile range [IQR] 0.2-9.8 y) in 1987-1999 to 9.6 y (IQR 3.2-11.6 y) in 2010-2019 (P < 0.0001). Elderly donors had equivalent outcomes to donors <70 y when transplanted in elderly recipients (≥70 y). Outcomes for young recipients that received grafts from elderly donor improved with time, with median survival of 10.1 y (IQR 3.9-11.5 y) in 2010-2019. BAR and survival outcomes following liver transplant (SOFT) scores predicted improved graft survival on time-to-event analysis in all donors aged >70 y. In low-risk recipients, evidenced by preallocation SOFT score <5, elderly donors had comparable outcomes to young (<40 y) and middle-aged donors (40-69 y). Increasing donor age was not associated with worse graft survival in transplants performed between 2010 and 2019.

Conclusions

Donors aged ≥70 y may be more comfortably considered for deceased donor liver transplantation, especially within low-risk recipients. The BAR and SOFT scores may be a useful guide for safely expanding the use of these theoretically riskier liver grafts.

Donor-Derived Bacterial Infections in Deceased Donor Liver Transplantation: Reassessment of Risk in the Era of Marginal Grafts

BACKGROUND

The shortage of available organs for liver transplant has, over time, led to the inclusion of donors at risk of transmitting bacterial infections. In Italy, depending on the severity of this risk, these organs are only allocated to patients in serious clinical conditions, consequently, their use in a shortage context is further restricted.

METHODS

We retrospectively analyzed a consecutive series of 194 liver transplants from deceased adult donors performed at our institute between 2019 and 2021 and performed a statistical comparison between 2 groups: recipients of livers with a risk of transmission of bacterial infection (BR group) vs recipients of livers with no risk (noBR group). Primary endpoints include 90-day and 1-year survival rates of recipients, and secondary endpoints focus on the incidence of complications of grade ≥3 according to Clavien-Dindo and donor-related infections.

RESULTS

Ninety-day and 1-year mortality in the BR vs noBR group was 5% vs 7% and 5% vs 14%, respectively. Major complications at 90 days occurred in 37% of the BR group vs 47% in the noBR group. No statistical differences were observed in the 2 recipient groups with respect to clinical outcomes. Cases of donor-derived infections also occurred in the noBR group.

CONCLUSIONS

Organs at risk of transmitting bacterial infections have comparable outcomes to other organs when appropriate risk reduction strategies are implemented. It is necessary to remove restrictions on these organs, which are becoming increasingly common in our shortage context.

Outcomes and risk factors for liver transplantation using steatotic grafts for hepatocellular carcinoma: a multicenter study

INTRODUCTION

A growing number of steatotic grafts have been used in liver transplantation (LT), including hepatocellular carcinoma (HCC) patients. However, the impact of steatotic grafts on the prognosis of HCC recipients remains unclear. This study aims to evaluate the impact of steatotic graft in long-term prognosis for HCC recipients and development an algorithm for minimizing the risk of these grafts.

MATERIALS AND METHODS

The clinicopathologic data of HCC patients undergoing LT from 2003 to 2022 in the United Network for Organ Sharing database was analyzed. The disease-free survival (DFS) and overall survival (OS) of recipients were compared between non-steatotic (macrosteatosis <30 %) and steatotic (macrosteatosis ≥30 %) graft groups after propensity score matching (PSM). Interaction analysis was conducted to identify factors that amplified the negative impact of steatotic grafts on DFS.

RESULTS

A total of 8345 eligible HCC patients were included. Three factors exhibited significant interaction effect with steatotic grafts: cold ischemia time ≥6h (HR = 1.447; P = 0.023), donor body mass index ≥40 (HR = 1.771; P = 0.018) and recipient with non-alcoholic fatty liver disease (HR = 1.632; P = 0.032). Hazard Associated with Macrosteatotic Liver (HAML) score was created based on these three factors. In HAML ≥1 cohort, the DFS and OS of steatotic graft group were significantly reduced compared to non-steatotic graft group. But in HAML = 0 cohort, no significant differences in DFS and OS were observed between the two groups.

CONCLUSIONS

The risk of steatotic grafts in LT for HCC could be minimized through evaluating HAML score.

Insulin-induced gene 2 alleviates ischemia-reperfusion injury in steatotic liver by inhibiting GPX4-dependent ferroptosis

Hepatic steatosis significantly elevates the vulnerability of the graft to ischemia-reperfusion (I/R) injury during liver transplantation (LT). We investigated the protective role of insulin-induced gene 2 (Insig2) in steatotic liver's I/R injury and underlying mechanisms. Employing mouse model with Insig2 knock-out or hepatocyte-specific overexpression and high-fat diets to induce steatosis, we subjected these mice to hepatic I/R injury. The primary hepatocytes isolated from steatotic liver were used in in vitro hypoxia/reoxygenation (H/R) experiment. Our integrated in vivo and in vitro approach uncovered that Insig2 deficiency exacerbated steatotic liver's damage following hepatic I/R injury, whereas its overexpression offers protection. Mechanically, integrative analysis of transcriptome, proteome, and metabolome found that Insig2 deficiency disturbed lipid metabolism and oxidative stress homeostasis, particularly inhibiting GPX4 expression to induce ferroptosis. Furthermore, chemical inhibition of ferroptosis reversed the deleterious effect of Insig2 deficiency; whereas the protective influence of Insig2 overexpression was negated by the target inhibition of GPX4, leading to an exacerbation of hepatic I/R damage. These insights underscored the potential of the Insig2-GPX4 axis as a therapeutic target, presenting a novel avenue for enhancing the resilience of steatotic liver grafts against I/R injury.

Prolonged allograft survival in liver transplantation

Introduction

Donor age has traditionally been considered a factor associated with allograft failure in liver transplantation. We sought to examine the characteristics and outcomes of all liver allografts with a cumulative age of over 80 years within the US to better understand liver senescence.

Methods

Using the UNOS STARfile, allografts with a cumulative age (sum of age at transplant plus post-transplant survival) of octogenarian, 90-99 nonagenarian, and 100 years or greater (centurion) were identified from all adult transplant recipients between 1990 and 2022. Donor and recipient data as well as outcomes were analyzed.

Results

There were 3437 octogenarian, 622 nonagenarian, and 29 centurion allografts. Donors from allografts with prolonged cumulative age had less diabetes, less alcohol use, and fewer infections compared to all other donors. Recipients had significantly lower MELD scores at the time of transplant and dialysis rates.

Conclusions

Careful matching of older donors with lower MELD recipients results in excellent outcomes as evidenced by the presence of prolonged cumulative age livers, demonstrating the resilience of the liver to senescent events in appropriately matched recipients.

Protective value of ischemia-free liver transplantation on post-transplant acute kidney injury

Background & Aims

Ischemia-free liver transplantation (IFLT) completely avoids ischemia-reperfusion injury (IRI), thus potentially reducing acute kidney injury (AKI) after liver transplantation (LT). Therefore, this study investigated whether IFLT has a protective effect against AKI after LT.

Methods

In total, 862 patients who had undergone LT between 2017 to 2022 were divided into an ischemia-free liver transplantation group (IFLT group) and conventional liver transplantation group (CLT group) based on the surgical methods used. Propensity score matching (PSM) was used for post hoc randomization in the 1:1 matching between the groups. Post-transplant kidney function, graft function, and patient survival were compared between the groups. Multivariate logistic regression analysis was used to identify the risk factors of AKI after LT.

Results

Overall, 745 out of 862 patients were finally enrolled, of whom 98 underwent IFLT. PSM created 94 pairs of patients. IFLT resulted in a significant reduction in Stage-3 AKI (3.2% vs. 16.0%, p = 0.003), severe AKI (SAKI) (13.8% vs. 25.5%, p = 0.044), and renal replacement therapy (RRT) ratio (3.2% vs. 12.8%, p = 0.015) compared with the CLT group. The early allograft dysfunction (EAD) incidence of the IFLT group significantly decreased (8.5% vs. 44.7%, p <0.001). Livers from the extended criteria donation (ECD) were received in 49 patients who underwent IFLT and 46 patients who underwent CLT. Compared with the ECD-CLT group, the Stage-3 AKI and SAKI incidence in the ECD-IFLT group were both decreased (p <0.05). Multivariate logistic regression analysis further confirmed that both using IFLT and avoiding ECD were protective factors for post-transplant Stage-3 AKI.

Conclusions

IFLT significantly reduces the incidence of post-transplant SCKI, Stage-3 AKI, and RRT. Importantly, this protective effect is also present in patients receiving ECD livers.

Impact and implications

Ischemia-free liver transplantation significantly reduces the incidence of severe acute kidney injury, Stage-3 acute kidney injury and renal replacement therapy after liver transplantation. Importantly, this protective effect is also present in patients receiving extended criteria donation livers.

Clinical trial number

ChiCTR2400081755.

Analysis of Unused Organ Donors in the Netherlands: Older Donor Age Associated With Higher Risk of Non-Utilization

This study aims to provide objective evidence for the subjectively observed increase in non-utilized donors and to investigate whether they share common risk factors, hypothesizing that the aging of the donor population may be a possible explanation. All referred deceased donors in the Netherlands between 2018 and 2023 were analyzed. A utilized donor was defined as a referred donor that resulted in at least one transplanted organ. A non-utilized donor was defined as a donor from whom no organ was transplanted as a result of the cessation. In total, 2,235 donors were defined as referred; 1,618 donors were utilized and 617 were non-utilized. A significant increase in referred donors aged >66 years was observed, together with an increase of 51% in non-utilized donors. The most frequent reasons for not utilizing a donor were found to be an agonal phase > 2 hours in DCD donors (45%) and an unacceptable medical history at screening (22%). Multivariable logistic regression analysis showed that increasing donor age (age 66-75 years OR 1.81, 95% CI 1.09-3.00), DCD donors (OR 4.37 95% CI 3.24-5.89, p < 0.01), history of hypertension (OR 1.29 95% CI 1.01-1.66, p = 0.04) and/or diabetes (OR 2.48 95% CI 1.75-3.51, p < 0.01) were associated with non-utilization. Non-utilized donors are significantly older, are more often DCD donors and have more co-morbidities, confirming the hypothesis that these donors are the more marginal donors.

Shortening the recipient warm ischemia time could be a strategy for expanding the liver donor pool

BACKGROUND

Shortening the recipient warm ischemia time (rWIT) has been proven to be effective for improving the short- and long-term outcomes after liver transplantation (LT) and offsets the negative impact of an extended cold ischemia time. However, few studies have been conducted to explore the prognostic effects of shortening the rWIT in transplantations using a liver graft from an extended-criteria donor (ECD).

AIM

To investigate whether shortening the rWIT could improve the outcomes of ECD LT.

METHODS

Rat ECD autologous orthotopic LT were performed with variable rWITs (0, 10, 20, and 30 minutes). Near-infrared fluorescence imaging (FI) was used for the real-time assessment of liver graft ischemia-reperfusion injury after the anhepatic phase. Survival was assessed, and liver function and histological analyses were performed on the third day after transplantation.

RESULTS

The FI curve growth rate and postoperative three-day survival rate significantly increased, and the liver function and Suzuki score of the liver grafts significantly improved when the rWIT was ≤ 10 minutes (P < 0.05).

CONCLUSION

The post-transplant outcomes were significantly better with a shorter rWIT (10 minutes or less) than with a longer rWIT, which could be a strategy for expanding the liver donor pool.

Exploring the Viability of Matching Marginal Donors With Low Renal Function Recipients in Liver Transplantation

BACKGROUND

Renal function varies among liver transplantation (LT) candidates with the same Model for End-Stage Liver Disease (MELD)3.0 score. The impact of marginal grafts on post-LT renal function and prognosis varies based on the pre-LT renal function. We explored the effects of matching recipients with low renal function to marginal donors on graft survival (GS) and post-LT kidney function.

METHODS

We analyzed data from the Scientific Registry of Transplant Recipients (SRTR), categorizing pre-LT renal function by estimated glomerular filtration rate (eGFR) into low (<30 mL/min/1.73 m2) and high (≥30 mL/min/1.73 m2). Marginal donors were defined by criteria including donation after cardiac death, age ≥ 65, severe macrosteatosis (≥30%), or body mass index ≥ 40 kg/m2. The primary outcome was to compare 3-year post-LT GS between patients with low and high pre-LT renal function. Additionally, we examined post-LT eGFR 1-3 months post-LT.

RESULTS

Of 13 279 LT recipients, 12 851 had high pre-LT eGFR and 428 had low pre-LT eGFR. Kaplan-Meier survival analysis showed that recipients with low pre-LT eGFR had significantly lower 3-year GS compared to those with high eGFR (p < 0.01). Recipients of organs from marginal donors also exhibited a significant reduction in 3-year GS (p < 0.01). This adverse effect persisted within the same MELD3.0 category. Additionally, lower pre-LT eGFR was associated with an increased risk of post-LT kidney function deterioration, especially among those receiving grafts from marginal donors. Multivariable logistic regression identified recipient age > 65 as a significant risk factor for post-LT kidney function decline (OR 3.34 [1.05-10.7]; p = 0.03).

DISCUSSION

GS was notably worse in recipients with low pre-LT eGFR, particularly when matched with marginal donors. A recipient age > 65 is a risk indicator for post-LT kidney function deterioration with marginal donors, underscoring the importance of careful donor-recipient matching, especially with compromised pre-LT kidney function.

Human spindle-shaped urine-derived stem cell exosomes alleviate severe fatty liver ischemia-reperfusion injury by inhibiting ferroptosis via GPX4

BACKGROUND

Severe hepatic steatosis can exacerbate Ischemia-reperfusion injury (IRI), potentially leading to early graft dysfunction and primary non-function. In this study, we investigated the heterogeneity of different subpopulations of Urine-derived stem cells (USCs) to explore the most suitable cell subtype for treating severe steatotic liver IRI.

METHODS

This study utilized scRNA-seq and Bulk RNA-seq to investigate the transcriptional heterogeneity between Spindle-shaped USCs (SS-USCs) and Rice-shaped USCs (RS-USCs). Additionally, rat fatty Liver transplantation (LT) model, mouse fatty liver IRI model, and Steatotic Hepatocyte Hypoxia-Reoxygenation (SHP-HR) model were constructed. Extracellular vesicles derived from SS-USCs and RS-USCs were isolated and subjected to mass spectrometry analysis. The therapeutic effects of Spindle-shaped USCs Exosomes (SS-USCs-Exo) and Rice-shaped USCs Exosomes (RS-USCs-Exo) were explored, elucidating their potential mechanisms in inhibiting ferroptosis and alleviating IRI.

RESULTS

Multiple omics analyses confirmed that SS-USCs possess strong tissue repair and antioxidant capabilities, while RS-USCs have the potential to differentiate towards specific directions such as the kidney, nervous system, and skeletal system, particularly showing great application potential in renal system reconstruction. Further experiments demonstrated in vivo and in vitro models confirming that SS-USCs and SS-USCs-Exo significantly inhibit ferroptosis and alleviate severe fatty liver IRI, whereas the effects of RS-USCs/RS-USCs-Exo are less pronounced. Analysis comparing the proteomic differences between SS-USCs-Exo and RS-USCs-Exo revealed that SS-USCs-Exo primarily inhibit ferroptosis and improve cellular viability by secreting exosomes containing Glutathione Peroxidase 4 (GPX4) protein. This highlights the most suitable cell subtype for treating severe fatty liver IRI.

CONCLUSIONS

SS-USCs possess strong tissue repair and antioxidant capabilities, primarily alleviating ferroptosis in the donor liver of fatty liver through the presence of GPX4 protein in their exosomes. This highlights SS-USCs as the most appropriate cell subtype for treating severe fatty liver IRI.

Perspectives and Tools in Liver Graft Assessment: A Transformative Era in Liver Transplantation

Liver transplantation is a critical and evolving field in modern medicine, offering life-saving treatment for patients with end-stage liver disease and other hepatic conditions. Despite its transformative potential, transplantation faces persistent challenges, including a global organ shortage, increasing liver disease prevalence, and significant waitlist mortality rates. Current donor evaluation practices often discard potentially viable livers, underscoring the need for refined graft assessment tools. This review explores advancements in graft evaluation and utilization aimed at expanding the donor pool and optimizing outcomes. Emerging technologies, such as imaging techniques, dynamic functional tests, and biomarkers, are increasingly critical for donor assessment, especially for marginal grafts. Machine learning and artificial intelligence, exemplified by tools like LiverColor, promise to revolutionize donor-recipient matching and liver viability predictions, while bioengineered liver grafts offer a future solution to the organ shortage. Advances in perfusion techniques are improving graft preservation and function, particularly for donation after circulatory death (DCD) grafts. While challenges remain-such as graft rejection, ischemia-reperfusion injury, and recurrence of liver disease-technological and procedural advancements are driving significant improvements in graft allocation, preservation, and post-transplant outcomes. This review highlights the transformative potential of integrating modern technologies and multidisciplinary approaches to expand the donor pool and improve equity and survival rates in liver transplantation.

Survival benefit of liver transplantation utilizing marginal donor organ according to ABO blood type

The current liver transplantation (LT) allocation policy focuses on the MELD scores, often overlooking factors like blood type and survival benefits. Understanding blood types' impact on survival benefits is crucial for optimizing the MELD 3.0 classification. This study used the United Network for Organ Sharing national registry database (2003-2020) to identify LT characteristics per ABO blood type and to determine the optimal MELD 3.0 scores for each blood type, based on survival benefits. The study included candidates of LT aged 18 years or older listed for LT (total N=150,815; A: 56,546, AB: 5841, B: 18,500, O: 69,928). Among these, 87,409 individuals (58.0%) underwent LT (A:32,156, AB: 4,362, B: 11,786, O: 39,105). Higher transplantation rates were observed in AB and B groups, with lower median MELD 3.0 scores at transplantation (AB: 21, B: 24 vs. A/O: 26, p <0.01) and shorter waiting times (AB: 101 d, B:172 d vs. A: 211 d, O: 201 d, p <0.01). A preference for donation after cardiac death (DCD) was seen in A and O recipients. Survival benefit analysis indicated that B blood type required higher MELD 3.0 scores for transplantation than A and O (donation after brain death transplantation: ≥15 in B vs. ≥11 in A/O; DCD transplantation: ≥21 in B vs. ≥11 in A, ≥15 in O). The study suggests revising the allocation policy to consider blood type for improved post-LT survival. This calls for personalized LT policies, recommending higher MELD 3.0 thresholds, particularly for individuals with type B blood.

Stratifying and predicting progression to acute liver failure during the early phase of acute liver injury

Acute liver failure (ALF) is a serious disease that progresses from acute liver injury (ALI) and that often leads to multiorgan failure and ultimately death. Currently, effective treatment strategies for ALF, aside from transplantation, remain elusive, partly because ALI is highly heterogeneous. Furthermore, clinicians lack a quantitative indicator that they can use to predict which patients hospitalized with ALI will progress to ALF and the need for liver transplantation. In our study, we retrospectively analyzed data from 319 patients admitted to the hospital with ALI. By applying a machine-learning approach and by using the SHapley Additive exPlanations (SHAP) algorithm to analyze time-course blood test data, we identified prothrombin time activity percentage (PT%) as a biomarker reflecting individual ALI status. Unlike previous studies predicting the need for liver transplantation in patients with ALF, our study focused on PT% dynamics. Use of this variable allowed us to stratify the patients with highly heterogeneous ALI into six groups with distinct clinical courses and prognoses, i.e. self-limited, intensive care-responsive, or intensive care-refractory patterns. Notably, these groups were well predicted by clinical data collected at the time of admission. Additionally, utilizing mathematical modeling and machine learning, we assessed the predictability of individual PT% dynamics during the early phase of ALI. Our findings may allow for optimizing medical resource allocation and early introduction of tailored individualized treatment, which may result in improving ALF prognosis.

Donors With Previous Malignancy: When Is It Safe to Proceed With Organ Transplantation?

The growing number of organ donors in the United States, from 14,011 in 2012 to 21,374 in 2022, highlights progress in addressing the critical issue of organ shortages. However, the demand remains high, with 17 patients dying daily while on the waiting list. As of August 2023, over 103,544 individuals are awaiting transplants, predominantly for kidneys (85.7%). To expand the donor pool, the inclusion of elderly donors, including those with a history of malignancies, is increasingly considered. In 2022, 7% of all donors were aged 65 and above, despite the complexities their medical histories may introduce, particularly the risk of donor-transmitted cancer (DTC). This review examines the challenges and potential benefits of using donors with known malignancy histories, balancing the risks of DTC against the urgency for transplants. A critical analysis is presented on current knowledge and the decision-making processes that consider cancer types, stages, and patient survival outcomes. The goal is to identify missed opportunities and improve strategies for safe and effective organ transplantation from this donor demographic.

Comparison of Vascular Complications Between Living-donor and Deceased-donor Liver Transplantation - A Systematic Review and Meta-analysis

BACKGROUND

Vascular complications commonly cause graft loss and morbidity after liver transplantation (LT). Comparative data on the risk of vascular complications are limited. Hence, the present meta-analysis was conducted to analyze the difference in vascular complications between living-donor LT (LDLT) and deceased-donor LT (DDLT).

METHODS

A literature search of three databases was conducted for studies comparing the incidence of vascular complications with LDLT and DDLT. The event rates and odds ratios (OR) with 95% confidence intervals (CI) were calculated using a random-effects model.

RESULTS

A total of 20 studies were included in the final analysis. There was no difference in the incidence of overall vascular complications (9.3%, 95% CI: 6.6-12.0 vs. 8.5%, 95% CI: 5.6-11.4) between LDLT and DDLT with OR 0.94 (95% CI: 0.73-1.21) (15 studies).There was a higher incidence of vascular complications with LDLT in older studies (published before 2013) but not in new studies. When comparing the individual complications, LDLT was associated with a higher incidence of hepatic artery thrombosis (HAT) (3.8%, 95% CI: 2.4-5.2 vs. 1.6%, 95% CI: 1.1-2.2)with OR 2.20 (95% CI: 1.53-3.17) (14 studies)and a significantly lower incidence of intra-abdominal bleeding(4.8%, 95% CI: 3.3-6.2 vs. 7.9%, 95% CI: 5.0-10.7) with OR 0.64 (95% CI: 0.47-0.87) (11 studies). However, there was no difference in the incidence (2.1%, 95% CI: 0.5-3.8 vs. 1.0%, 95% CI: 0.1-1.9) of portal vein thrombosis between LDLT and DDLT with OR 1.85 (95% CI: 0.82-4.18) (6 studies).

CONCLUSION

Despite a comparable risk of vascular complications between LDLT and DDLT, LDLT was associated with a higher risk of HAT and a lower risk of intraprocedural bleeding. Further studies are required to analyze the effect of donor-recipient characteristics and surgical techniques on the risk of vascular complications.

Molecular Mechanisms of Fibrosis in Cholestatic Liver Diseases and Regenerative Medicine-Based Therapies

The aim of this review is to explore the potential of new regenerative medicine approaches in the treatment of cholestatic liver fibrosis. Cholestatic liver diseases, such as primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and biliary atresia (BA), due to the accumulation of bile, often progress to liver fibrosis, cirrhosis, and liver failure. When the disease becomes severe enough to require liver transplantation. Deeply understanding the disease's progression and fibrosis formation is crucial for better diagnosis and treatment. Current liver fibrosis treatments mainly target the root causes and no direct treatment method in fibrosis itself. Recent advances in regenerative medicine offer a potential approach that may help find the ways to target fibrosis directly, offering hope for improved outcomes. We also summarize, analyze, and discuss the current state and benefits of regenerative medicine therapies such as mesenchymal stem cell (MSC) therapy, induced pluripotent stem cells (iPSCs), and organoid technology, which may help the treatment of cholestatic liver diseases. Focusing on the latest research may reveal new targets and enhance therapeutic efficacy, potentially leading to more effective management and even curative strategies for cholestatic liver diseases.

S100A9 regulates M1 macrophage polarization and exacerbates steatotic liver ischemia-reperfusion injury

OBJECTIVE

Steatotic livers exhibit higher susceptibility to ischemia reperfusion (IR) injury, which increase the risk of primary graft non-function following liver transplantation. S100A9 is identified as a pivotal innate immune sensor that regulates the progression of liver diseases. However, its significance in steatotic liver IR injury remains under-investigated.

METHODS

In mice model, we generated S100A9 knockout (S100A9 KO) mice to investigate the role of S100A9 in IR-stimulated steatotic livers. In vitro, primary bone marrow-derived macrophages were utilized to explore the effect of S100A9 in regulating macrophage polarization and inflammation.

RESULTS

S100A9 expression was markedly increased in steatotic livers of mice subjected to IR insult. S100A9 deletion significantly attenuated liver inflammatory injury, as evidenced by the diminished infiltration of both monocytes/macrophages and neutrophils (p < 0.05). The expression of proinflammatory factors was reduced (p < 0.05) at the same time. Additionally, S100A9-deficient livers demonstrated M1 polarization decrease and Toll-like receptor 4 (TLR4) suppression (p < 0.05). In vitro, genetic TLR4 inhibition led to nuclear factor kappa B (NF-κB) inactivation and subsequent M1 polarization decrease (p < 0.05) in macrophages treated with recombinant S100A9. Conclusion In this study, we highlight the pivotal role of TLR4/NF-κB as a critical mediator of S100A9 in inducing M1 macrophage polorization- dependent inflammation in steatotic livers IR injury.

Multinational Analysis of Marginal Liver Grafts Based on the Eurotransplant Extended Donor Criteria

OBJECTIVE

To evaluate the outcome of marginal liver grafts based on the Eurotransplant extended criteria donor (ECD) criteria.

BACKGROUND

Eurotransplant uses a broad definition of ECD criteria (age >65 years, steatosis >40%, body mass index >30 kg/m 2 , intensive care unit stay >7 days, donation after circulatory death, and certain laboratory parameters) for allocating organs to recipients who have consented to marginal grafts. Historically, marginal liver grafts were associated with increased rates of dysfunction.

METHODS

Retrospective cohort analysis using the German Transplant Registry and the U.S. Scientific Registry of Transplant Recipients (SRTR) from 2006 to 2016. Results were validated with recent SRTR data (2017-2022). Donors were classified according to the Eurotransplant ECD criteria, donation after circulatory death was excluded. Data were analyzed with cutoff prediction, binomial logistic regression, and multivariate Cox regression.

RESULTS

The study analyzed 92,330 deceased brain-dead donors (87% SRTR) and 70,374 transplants (87% SRTR) in adult recipients. Predominant ECD factors were donor age in Germany (30%) and body mass index in the United States (28%). Except for donor age, grafts meeting ECD criteria were not associated with impaired 1 or 3-year survival. Cutoffs had little to no predictive value for 30-day graft survival (area under the receiver operating curve: 0.49-0.52) and were nominally higher for age (72 vs 65 years) in Germany as compared with those defined by current Eurotransplant criteria.

CONCLUSIONS

The outcome of transplanted grafts from higher risk donors was nearly equal to standard donors with Eurotransplant criteria failing to predict survival of marginal grafts. Modifying ECD criteria could improve graft allocation and potentially expand the donor pool.

Gut Microbiota and Liver Regeneration: A Synthesis of Evidence on Structural Changes and Physiological Mechanisms

Liver regeneration (LR) is a unique biological process with the ability to restore up to 70% of the organ. This allows for the preservation of liver resections for various liver tumors and for living donor liver transplantation (LDLT). However, in some cases, LR is insufficient and interventions that can improve LR are urgently needed. Gut microbiota (GM) is one of the factors influencing LR, as the liver and intestine are intimately connected through the gut-liver axis. Thus, healthy GM facilitates normal LR, whereas dysbiosis leads to impaired LR due to imbalance of bile acids, inflammatory cytokines, microbial metabolites, signaling pathways, etc. Therefore, GM can be considered as a new possible therapeutic target to improve LR. In this review, we critically observe the current knowledge about the influence of gut microbiota (GM) on liver regeneration (LR) and the possibility to improve this process, which may reduce complication and mortality rates after liver surgery. Although much research has been done on this topic, more clinical trials and systemic reviews are urgently needed to move this type of intervention from the experimental phase to the clinical field.

Potential of Raman-Reflectance Combination in Quantifying Liver Steatosis and Fat Droplet Size: Evidence From Monte Carlo Simulations and Phantom Studies

This study explores a combined strategy of Raman and reflectance spectroscopy for quantifying liver fat content and fat droplet size, crucial in assessing donor livers. By using Monte Carlo simulations and experimental setups with oil-in-water phantoms, our findings indicate that Raman scattering can solely differentiate between varying fat contents. At the same time, reflectance intensity is influenced by both fat content and oil droplet size, with a more pronounced sensitivity to fat droplet size. This study demonstrates the efficacy of combined Raman and reflectance spectroscopy in assessing liver steatosis and fat droplet size, potentially aiding in assessing donor livers for transplantation.

Beyond 75: Graft Allocation and Organ Utility Implications in Liver Transplantation

Background

The global surge in aging has intensified debates on liver transplantation (LT) for candidates aged 75 y and older, given the prevalent donor scarcity. This study examined both the survival benefits and organ utility of LT for this age group.

Methods

A total of 178 469 adult LT candidates from the United Network for Organ Sharing database (2003-2022) were analyzed, with 112 266 undergoing LT. Post-LT survival outcomes and waitlist dropout rates were monitored across varying age brackets. Multivariable Cox regression analysis determined prognostic indicators. The 5-y survival benefit was assessed by comparing LT recipients to waitlist candidates using hazard ratios. Organ utility was evaluated through a simulation model across various donor classifications.

Results

Among candidates aged 75 y and older, 343 received LT. The 90-d graft and patient survival rates for these patients were comparable with those in other age categories; however, differences emerged at 1 and 3 y. Age of 75 y or older was identified as a significant negative prognostic indicator for 3-y graft survival (hazard ratio: 1.72 [1.20-2.42], P < 0.01). Dropout rates for the 75 y and older age category were 12.0%, 24.1%, and 35.1% at 90 d, 1 y, and 3 y, respectively. The survival benefit of LT for the 75 y and older cohort was clear when comparing outcomes between LT recipients and those on waitlists. However, organ utility considerations did not favor allocating livers to this age group, regardless of donor type. Comparing 3-y patient survival between LT using donors aged 60 y and younger and older than 60 y showed no significant difference (P = 0.50) in the 75 y or older cohort.

Conclusions

Although LT offers survival benefits to individuals aged 75 y and older, the system may need rethinking to optimize the use of scarce donor livers, perhaps by matching older donors with older recipients.

Machine Perfusion Technology Drives a Major Growth Surge in Liver Transplantation

INTRODUCTION

Machine perfusion (MP) opens the possibility to overcome the existing disbalance between supply and demand in liver transplantation. However, it has not been widely adopted across the country. We explored trends of MP adoption in the United States and their effect on center volume (CV).

METHODS

We used the Standard Transplant Analysis and Research datafile from January 2010 to July 2023 to assess CV changes following MP implementation. We classified centers into MP nonusers, low MP users, and high MP (HMP) users. We used interrupted time series analysis to measure changing patterns of HMP CV before and after January 2016, marking the occurrence of the first MP case. High-volume institutions in 2015 were additionally compared to their equivalents in 2022 stratified by their MP status using Wilcoxon rank sum test.

RESULTS

In our controlled interrupted time series, HMP centers had a sustained yet moderate positive trend in volume (P < 0.001). Comparing only high-volume institutions, we found no difference in the number of transplants performed in 2015 to their equivalents in 2022. In the stratified analysis, only HMP centers had a significant increase in the total number of transplants in 2022 (P = 0.032).

CONCLUSIONS

MP has demonstrated to greatly improve outcomes for recipients of liver transplantation. Here, we demonstrate that centers that incorporate MP could potentially benefit from a growth in their practice as well. Further studies are needed to better characterize the features that drive transplant centers to grow across time.

Mesenchymal stem cell therapy for liver transplantation: clinical progress and immunomodulatory properties

Although liver transplantation (LT) is an effective strategy for end-stage liver diseases, the shortage of donor organs and the immune rejection hinder its widespread implementation in clinical practice. Mesenchymal stem cells (MSCs) transplantation offers a promising approach for patients undergoing liver transplantation due to their immune regulatory capabilities, hepatic protection properties, and multidirectional differentiation potential. In this review, we summarize the potential applications of MSCs transplantation in various LT scenarios. MSCs transplantation has demonstrated effectiveness in alleviating hepatic ischemia-reperfusion injury, enhancing the viability of liver grafts, preventing acute graft-versus-host disease, and promoting liver regeneration in split LT therapy. We also discuss the clinical progress, and explore the immunomodulatory functions of MSCs in response to both adaptive and innate immune responses. Furthermore, we emphasize the interactions between MSCs and different immune cells, including T cells, B cells, plasma cells, natural killer cells, dendritic cells, Kupffer cells, and neutrophils, to provide new insights into the immunomodulatory properties of MSCs in adoptive cell therapy.

Oleanolic acid alleviating ischemia-reperfusion injury in rat severe steatotic liver via KEAP1/NRF2/ARE

Severe steatosis in donor livers is contraindicated for transplantation due to the high risk of ischemia-reperfusion injury (IRI). Although Ho-1 gene-modified bone marrow mesenchymal stem cells (HO-1/BMMSCs) can mitigate IRI, the role of gut microbiota and metabolites in this protection remains unclear. This study aimed to explore how gut microbiota and metabolites contribute to HO-1/BMMSCs-mediated protection against IRI in severe steatotic livers. Using rat models and cellular models (IAR20 and THLE-2 cells) of steatotic liver IRI, this study revealed that ischemia-reperfusion led to significant liver and intestinal damage, heightened immune responses, impaired liver function, and altered gut microbiota and metabolite profiles in rats with severe steatosis, which were partially reversed by HO-1/BMMSCs transplantation. Integrated microbiome and metabolome analyses identified gut microbial metabolite oleanolic acid as a potential protective agent against IRI. Experimental validation showed that oleanolic acid administration alone alleviated IRI and inhibited ferroptosis in both rat and cellular models. Network pharmacology and molecular docking implicated KEAP1/NRF2 pathway as a potential target of oleanolic acid. Indeed, OA experimentally upregulated NRF2 activity, which underlies its inhibition of ferroptosis and protection against IRI. The gut microbial metabolite OA protects against IRI in severe steatotic liver by promoting NRF2 expression and activity, thereby inhibiting ferroptosis.

Landscape of donor cause of death and its impact on liver transplant outcomes: a ten-year analysis from the UNOS database

BACKGROUND

Cause of death (COD) is a predictor of liver transplant (LT) outcomes independent of donor age, yet has not been recently reappraised.

METHODS

Analyzing UNOS database (2013-2022), the study explored COD trends and impacts on one-year post-LT graft survival (GS) and hazard ratios (HR) for graft failure.

RESULTS

Of 80,282 brain-death donors, 55,413(69.0%) underwent initial LT. Anoxia became the predominant COD in 2015, increasing from 29.0% in 2013 to 45.1% in 2021, with notable increases in drug intoxication. Survival differences between anoxia and cerebrovascular accidents (CVA) recently became insignificant (P=0.95). Further analysis showed improved GS from intracranial hemorrhage/stroke (previously worse; P<0.01) (P=0.70). HRs for post-1-year graft failure showed reduced significance of CVA (vs.Anoxia) and intracranial hemorrhage/stroke (vs.any other COD) recently. Donors with intracranial hemorrhage/stroke, showing improved survival and HR, were allocated to recipients with lower MELD-Na, contrasting the trend for drug intoxication CODs.

DISCUSSION

CVA, traditionally linked with poorer outcomes, shows improved GS and HRs (vs.Anoxia). This could be due to rising drug intoxication cases and the allocation of donors with drug intoxication to recipients with higher MELD-Na, and those with CVA to recipients with lower scores. While COD remains crucial in donor selection, proper matching can mitigate differences among CODs.

The impact of macro- and micro-steatosis on the outcomes of patients who undergo liver transplant: Analysis of the UNOS-STAR database

BACKGROUND AND AIMS

The presence of steatosis in a donor liver and its relation to post-transplantation outcomes are not well defined. This study evaluates the effect of the presence and severity of micro- and macro-steatosis of a donor graft on post-transplantation outcomes.

METHODS

The UNOS-STAR registry (2005-2019) was used to select patients who received a liver transplant graft with hepatic steatosis. The study cohort was stratified by the presence of macro- or micro-vesicular steatosis, and further stratified by histologic grade of steatosis. The primary endpoints of all-cause mortality and graft failure were compared using sequential Cox regression analysis. Analysis of specific causes of mortality was further performed.

RESULTS

There were 9184 with no macro-steatosis (control), 150 with grade 3 macro-steatosis, 822 with grade 2 macro-steatosis and 12 585 with grade 1 macro-steatosis. There were 10 320 without micro-steatosis (control), 478 with grade 3 micro-steatosis, 1539 with grade 2 micro-steatosis and 10 404 with grade 1 micro-steatosis. There was no significant difference in all-cause mortality or graft failure among recipients who received a donor organ with any evidence of macro- or micro-steatosis, compared to those receiving non-steatotic grafts. There was increased mortality due to cardiac arrest among recipients of a grade 2 macro-steatosis donor organ.

CONCLUSION

This study shows no significant difference in all-cause mortality or graft failure among recipients who received a donor liver with any degree of micro- or macro-steatosis. Further analysis identified increased mortality due to specific aetiologies among recipients receiving donor organs with varying grades of macro- and micro-steatosis.

Multi-omics analysis reveals a crosstalk between ferroptosis and peroxisomes on steatotic graft failure after liver transplantation

To identify the mechanism underlying macrosteatosis (MaS)-related graft failure (GF) in liver transplantation (LT) by multi-omics network analysis. The transcriptome and metabolome were assayed in graft and recipient plasma in discovery (n = 68) and validation (n = 89) cohorts. Differentially expressed molecules were identified by MaS and GF status. Transcriptional regulatory networks were generated to explore the mechanism for MaS-related inferior post-transplant prognosis. The differentially expressed molecules associated with MaS and GF were enriched in ferroptosis and peroxisome-related pathways. Core features of MaS-related GF were presented on decreased transferrin and impaired anti-oxidative capacity dependent upon dysregulation of transcription factors hepatocyte nuclear factor 4A (HNF4A) and hypoxia-inducible factor 1A (HIF1A). Furthermore, miR-362-3p and miR-299-5p inhibited transferrin and HIF1A expression, respectively. Lower M2 macrophages but higher memory CD4 T cells were observed in MaS-related GF cases. These results were validated in clinical specimens and cellular models. Systemic analysis of multi-omics data depicted a panorama of biological pathways deregulated in MaS-related GF. Transcriptional regulatory networks centered on transferrin and anti-oxidant responses were associated with poor MaS graft quality, qualifying as potential targets to improve prognosis of patients after LT.

A narrative review: predicting liver transplant graft survival using artificial intelligence modeling

Liver transplantation is the only treatment for patients with liver failure. As demand for liver transplantation grows, it remains a challenge to predict the short- and long-term survival of the liver graft. Recently, artificial intelligence models have been used to evaluate the short- and long-term survival of the liver transplant. To make the models more accurate, suitable liver transplantation characteristics must be used as input to train them. In this narrative review, we reviewed studies concerning liver transplantations published in the PubMed, Web of Science, and Cochrane databases between 2017 and 2022. We picked out 17 studies using our selection criteria and analyzed them, evaluating which medical characteristics were used as input for creation of artificial intelligence models. In eight studies, models estimating only short-term liver graft survival were created, while in five of the studies, models for the prediction of only long-term liver graft survival were built. In four of the studies, artificial intelligence algorithms evaluating both the short- and long-term liver graft survival were created. Medical characteristics that were used as input in reviewed studies and had the biggest impact on the accuracy of the model were the recipient's age, recipient's body mass index, creatinine levels in the recipient's serum, recipient's international normalized ratio, diabetes mellitus, and recipient's model of end-stage liver disease score. To conclude, in order to define important liver transplantation characteristics that could be used as an input for artificial intelligence algorithms when predicting liver graft survival, more models need to be created and analyzed, in order to fully support the results of this review.

Liver transplantation for intrahepatic cholangiocarcinoma: who, when and how

PURPOSE OF REVIEW

Using transplant oncology principles, selected patients with intrahepatic cholangiocarcinoma (iCCA) may achieve long-term survival after liver transplantation. Strategies for identifying and managing these patients are discussed in this review.

RECENT FINDINGS

Unlike initial reports, several modern series have reported positive outcomes after liver transplantation for iCCA. The main challenges are in identifying the appropriate candidates and graft scarcity. Tumor burden and response to neoadjuvant therapies have been successfully used to identify favorable biology in unresectable cases. New molecular biomarkers will probably predict this response in the future. Also, new technologies and better strategies have been used to increase graft availability for these patients without affecting the liver waitlist.

SUMMARY

Liver transplantation for the management of patients with unresectable iCCA is currently a reality under strict research protocols. Who is a candidate for transplantation, when to use neoadjuvant and locoregional therapies, and how to increase graft availability are the main topics of this review.

Applications, advancements, and challenges of 3D bioprinting in organ transplantation

To date, organ transplantation remains an effective method for treating end-stage diseases of various organs. In recent years, despite the continuous development of organ transplantation technology, a variety of problems restricting its progress have emerged one after another, and the shortage of donors is at the top of the list. Bioprinting is a very useful tool that has huge application potential in many fields of life science and biotechnology, among which its use in medicine occupies a large area. With the development of bioprinting, advances in medicine have focused on printing cells and tissues for tissue regeneration and reconstruction of viable human organs, such as the heart, kidneys, and bones. In recent years, with the development of organ transplantation, three-dimensional (3D) bioprinting has played an increasingly important role in this field, giving rise to many unsolved problems, including a shortage of organ donors. This review respectively introduces the development of 3D bioprinting as well as its working principles and main applications in the medical field, especially in the applications, and advancements and challenges of 3D bioprinting in organ transplantation. With the continuous update and progress of printing technology and its deeper integration with the medical field, many obstacles will have new solutions, including tissue repair and regeneration, organ reconstruction, etc., especially in the field of organ transplantation. 3D printing technology will provide a better solution to the problem of donor shortage.

Ferrostatin-1 improves prognosis and regulates gut microbiota of steatotic liver transplantation recipients in rats

Aims: To investigate the effects of Ferrostatin-1 (Fer-1) on improving the prognosis of liver transplant recipients with steatotic liver grafts and regulating gut microbiota in rats. Methods: We obtained steatotic liver grafts and established a liver transplantation model. Recipients were divided into sham, liver transplantation and Fer-1 treatment groups, which were assessed 1 and 7 days after surgery (n = 6). Results & conclusion: Fer-1 promotes recovery of the histological structure and function of steatotic liver grafts and the intestinal tract, and improves inflammatory responses of recipients following liver transplantation. Fer-1 reduces gut microbiota pathogenicity, and lowers iron absorption and improves fat metabolism of recipients, thereby protecting steatotic liver grafts.

Influence of donor age on liver transplantation outcomes: A multivariate analysis and comparative study

BACKGROUND

The growing disparity between the rising demand for liver transplantation (LT) and the limited availability of donor organs has prompted a greater reliance on older liver grafts. Traditionally, utilizing livers from elderly donors has been associated with outcomes inferior to those achieved with grafts from younger donors. By accounting for additional risk factors, we hypothesize that the utilization of older liver grafts has a relatively minor impact on both patient survival and graft viability.

AIM

To evaluate the impact of donor age on LT outcomes using multivariate analysis and comparing young and elderly donor groups.

METHODS

In the period from April 2013 to December 2018, 656 adult liver transplants were performed at the University Hospital Merkur. Several multivariate Cox proportional hazards models were developed to independently assess the significance of donor age. Donor age was treated as a continuous variable. The approach involved univariate and multivariate analysis, including variable selection and assessment of interactions and transformations. Additionally, to exemplify the similarity of using young and old donor liver grafts, the group of 87 recipients of elderly donor liver grafts (≥ 75 years) was compared to a group of 124 recipients of young liver grafts (≤ 45 years) from the dataset. Survival rates of the two groups were estimated using the Kaplan-Meier method and the log-rank test was used to test the differences between groups.

RESULTS

Using multivariate Cox analysis, we found no statistical significance in the role of donor age within the constructed models. Even when retained during the entire model development, the donor age's impact on survival remained insignificant and transformations and interactions yielded no substantial effects on survival. Consistent insignificance and low coefficient values suggest that donor age does not impact patient survival in our dataset. Notably, there was no statistical evidence that the five developed models did not adhere to the proportional hazards assumption. When comparing donor age groups, transplantation using elderly grafts showed similar early graft function, similar graft (P = 0.92), and patient survival rates (P = 0.86), and no significant difference in the incidence of postoperative complications.

CONCLUSION

Our center's experience indicates that donor age does not play a significant role in patient survival, with elderly livers performing comparably to younger grafts when accounting for other risk factors.

Current Understanding of Marginal Grafts in Liver Transplantation

End-stage liver disease (ESLD), stemming from a spectrum of chronic liver pathologies including chronic liver failure, acute cirrhosis decompensation and hepatocellular carcinoma, imposes a significant global healthcare burden. Liver transplantation (LT) remains the only treatment for ESLD. However, the escalating mortality on transplant waitlists has prompted the utilization of marginal liver grafts in LT procedures. These grafts primarily encompass elderly livers, steatotic livers, livers from donation after circulatory death, split livers and those infected with the hepatitis virus. While the expansion of the donor pool offers promise, it also introduces concomitant risks. These encompass graft failure, biliary and cardiovascular complications, the recurrence of liver disease and reduced patient and graft survival. Consequently, various established strategies, ranging from improved donor-recipient matching to surgical interventions, have emerged to mitigate these risks. This article undertakes a comprehensive assessment of the current landscape, evaluating the viability of diverse marginal liver grafts. Additionally, it synthesizes approaches aimed at enhancing the quality of such marginal liver grafts. The overarching objective is to augment the donor pool and ameliorate the risk factors associated with the shortage of liver grafts.

Integrated multi-omic analysis identifies fatty acid binding protein 4 as a biomarker and therapeutic target of ischemia-reperfusion injury in steatotic liver transplantation

BACKGROUND AND AIMS

Due to a lack of donor grafts, steatotic livers are used more often for liver transplantation (LT). However, steatotic donor livers are more sensitive to ischemia-reperfusion (IR) injury and have a worse prognosis after LT. Efforts to optimize steatotic liver grafts by identifying injury targets and interventions have become a hot issue.

METHODS

Mouse LT models were established, and 4D label-free proteome sequencing was performed for four groups: normal control (NC) SHAM, high-fat (HF) SHAM, NC LT, and HF LT to screen molecular targets for aggravating liver injury in steatotic LT. Expression detection of molecular targets was performed based on liver specimens from 110 donors to verify its impact on the overall survival of recipients. Pharmacological intervention using small-molecule inhibitors on an injury-related target was used to evaluate the therapeutic effect. Transcriptomics and metabolomics were performed to explore the regulatory network and further integrated bioinformatics analysis and multiplex immunofluorescence were adopted to assess the regulation of pathways and organelles.

RESULTS

HF LT group represented worse liver function compared with NC LT group, including more apoptotic hepatocytes (P < 0.01) and higher serum transaminase (P < 0.05). Proteomic results revealed that the mitochondrial membrane, endocytosis, and oxidative phosphorylation pathways were upregulated in HF LT group. Fatty acid binding protein 4 (FABP4) was identified as a hypoxia-inducible protein (fold change > 2 and P < 0.05) that sensitized mice to IR injury in steatotic LT. The overall survival of recipients using liver grafts with high expression of FABP4 was significantly worse than low expression of FABP4 (68.5 vs. 87.3%, P < 0.05). Adoption of FABP4 inhibitor could protect the steatotic liver from IR injury during transplantation, including reducing hepatocyte apoptosis, reducing serum transaminase (P < 0.05), and alleviating oxidative stress damage (P < 0.01). According to integrated transcriptomics and metabolomics analysis, cAMP signaling pathway was enriched following FABP4 inhibitor use. The activation of cAMP signaling pathway was validated. Microscopy and immunofluorescence staining results suggested that FABP4 inhibitors could regulate mitochondrial membrane homeostasis in steatotic LT.

CONCLUSIONS

FABP4 was identified as a hypoxia-inducible protein that sensitized steatotic liver grafts to IR injury. The FABP4 inhibitor, BMS-309403, could activate of cAMP signaling pathway thereby modulating mitochondrial membrane homeostasis, reducing oxidative stress injury in steatotic donors.

Application of extended criteria donor grafts in liver transplantation for acute-on-chronic liver failure: A retrospective cohort study

BACKGROUND

There is no consensus on the usage of extended criteria donor (ECD) grafts in liver transplantation (LT) for acute-on-chronic liver failure (ACLF) patients.

AIM

To summarize the experience of using ECD livers in ACLF-LT.

METHODS

A retrospective cohort study was conducted, enrolling patients who underwent LT at the First Affiliated Hospital of Sun Yat-Sen University from January 2015 to November 2021. The patients were divided into ECD and non-ECD groups for analysis.

RESULTS

A total of 145 recipients were enrolled in this study, of which ECD and non-ECD recipients accounted for 53.8% and 46.2%, respectively. Donation after cardiac death (DCD) recipients accounted for the minority compared with donation after brain death (DBD) recipients (16.6% vs 83.4%). Neither overall survival nor graft survival significantly differed between ECD and non-ECD and DCD and DBD recipients. ECD grafts were associated with a significantly higher incidence of early allograft dysfunction (EAD) than non-ECD grafts (67.9% vs 41.8%, P = 0.002). Postoperative outcomes between DCD and DBD recipients were comparable (P > 0.05). ECD graft (P = 0.009), anhepatic phase (P = 0.034) and recipient gamma glutamyltransferase (P = 0.016) were independent risk factors for EAD. Recipient preoperative number of extrahepatic organ failures > 2 (P = 0.015) and intraoperative blood loss (P = 0.000) were independent predictors of poor post-LT survival.

CONCLUSION

Although related to a higher risk of EAD, ECD grafts can be safely used in ACLF-LT. The main factors affecting post-LT survival in ACLF patients are their own severe preoperative disease and intraoperative blood loss.

Activation of NLRP3 Inflammasome via Drp1 Overexpression in Kupffer Cells Aggravates Ischemia-reperfusion Injury in Hepatic Steatosis

Background and Aims

Donors with fatty livers are considered to address the shortage of livers for transplantation, but those livers are particularly sensitive to ischemia-reperfusion injury (IRI), and an increased incidence of graft failure is observed. Kupffer cells account for 20-35% of liver nonparenchymal cells, and have been shown to participate in the process of IRI and inflammatory reactions of hepatic steatosis. NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) is an intracellular sensor activated by Kupffer cells to promote generation and participates in IRI. Dynamics-associated protein 1 (Drp1) is one of the main proteins regulating mitochondrial division and exacerbates IRI by affecting mitochondrial dynamics. The mechanism of interaction of Kupffer cells with Drp1 and NLRP3 to aggravate IRI has not been clarified.

Methods

A mouse model of hepatic steatosis was established by feeding the mice with a high-fat diet. In vitro experiments were performed using AML12 normal mouse liver cells and RAW264.7 mononuclear macrophage cells cultured in medium with palmitate and oleic acid. Western blotting and immunohistochemical (IHC) staining were used to detect the expression of NLRPP3 and Drp1 in IRI in the control and high-fat diet groups. The expression of F4/80+ cells during IRI in hepatic steatosis was verified by IHC staining, and the role of NLRPP3 and Drp1 in Kupffer-cell mediated IRI was investigated by targeting Drp-1 inhibition.

Results

Drp1 and NLRP3 expression was increased during IRI in hepatic steatosis, and the expression of Drp1 and NLRP3 were decreased after the elimination of Kupffer cells. That indicated Kupffer cells were involved in the process of IRI in hepatic steatosis through the action of Drp1 and NLRP3. After Drp1 inhibition, liver function was restored and NLRP3 expression level was reduced.

Conclusions

Kupffer cells aggravated IRI in hepatic steatosis via NLRP3 and Drp1. Drp1 inhibitors might be useful as specific therapeutics to alleviate IRI in hepatic steatosis and may have promise in case of liver donor shortage.

Hepatocellular Carcinoma: Surveillance, Diagnosis, Evaluation and Management

Hepatocellular carcinoma (HCC) ranks fourth in cancer-related deaths worldwide. Semiannual surveillance of the disease for patients with cirrhosis or hepatitis B virus allows for early detection with more favorable outcomes. The current underuse of surveillance programs demonstrates the need for intervention at both the patient and provider level. Mail outreach along with navigation provision has proven to increase surveillance follow-up in patients, while provider-targeted electronic medical record reminders and compliance reports have increased provider awareness of HCC surveillance. Imaging is the primary mode of diagnosis in HCC with The Liver Imaging Reporting and Data System (LI-RADS) being a widely accepted comprehensive system that standardizes the reporting and data collection for HCC. The management of HCC is complex and requires multidisciplinary team evaluation of each patient based on their preference, the state of the disease, and the available medical and surgical interventions. Staging systems are useful in determining the appropriate intervention for HCC. Early-stage HCC is best managed by curative treatment modalities, such as liver resection, transplant, or ablation. For intermediate stages of the disease, transarterial local regional therapies can be applied. Advanced stages of the disease are treated with systemic therapies, for which there have been recent advances with new drug combinations. Previously sorafenib was the mainstay systemic treatment, but the recent introduction of atezolizumab plus bevacizumab proves to have a greater impact on overall survival. Although there is a current lack of improved outcomes in Phase III trials, neoadjuvant therapies are a potential avenue for HCC management in the future.

Hepatic ischemia-reperfusion syndrome and its effect on the cardiovascular system: The role of treprostinil, a synthetic prostacyclin analog

Hepatic ischemia-reperfusion syndrome has been the subject of intensive study and experimentation in recent decades since it is responsible for the outcome of several clinical entities, such as major hepatic resections and liver transplantation. In addition to the organ's post reperfusion injury, this syndrome appears to play a central role in the dysfunction of distant tissues and systems. Thus, continuous research should be directed toward finding effective therapeutic options to improve the outcome and reduce the postoperative morbidity and mortality rates. Treprostinil is a synthetic analog of prostaglandin I2, and its experimental administration has shown encouraging results. It has already been approved by the Food and Drug Administration in the United States for pulmonary arterial hypertension and has been used in liver transplantation, where preliminary encouraging results showed its safety and feasibility by using continuous intravenous administration at a dose of 5 ng/kg/min. Treprostinil improves renal and hepatic function, diminishes hepatic oxidative stress and lipid peroxidation, reduces hepatictoll-like receptor 9 and inflammation, inhibits hepatic apoptosis and restores hepatic adenosine triphosphate (ATP) levels and ATP synthases, which is necessary for functional maintenance of mitochondria. Treprostinil exhibits vasodilatory properties and antiplatelet activity and regulates proinflammatory cytokines; therefore, it can potentially minimize ischemia-reperfusion injury. Additionally, it may have beneficial effects on cardiovascular parameters, and much current research interest is concentrated on this compound.

Utilization of hepatitis B surface antigen-positive donors in liver transplantation for recipients with hepatocellular carcinoma: a retrospective and propensity score matching analysis

Introduction

The use of extended criteria donor (ECD) grafts such as donor with infection of hepatitis B virus (HBV) is a potential solution for organ shortage. In this study, we aimed to evaluate the safety and long-term survival of utilization of hepatitis B surface antigen-positive (HBsAg+) donor livers in HCC patients using propensity score matching (PSM) analysis.

Methods

Forty-eight donors with HBsAg-positive and 279 donors with HBsAg-negative were transplanted and enrolled in this study. PSM analysis were used to eliminate selection bias. Perioperative data and survival were collected and analyzed.

Results

PSM generated 44 patient pairs. When comparing intra- and post-operative data, no significant difference was found between groups (P > 0.05). Patients with a HBsAg-positive donor had significantly worse progression-free survival (1-year: 65.9% vs. 90.9%; 3-year: 18.1% vs. 70.4%, P = 0.0060) and overall survival (1-year: 84.1% and 95.4%; 3-year: 27.2% vs. 79.5%, P = 0.0039). In multivariate analysis, donor HBsAg-positivity was an independent risk factor for survival and occurrence (P = 0.005 and 0.025, respectively).

Conclusion

In conclusion, with adequate antiviral prophylaxis and treatment, utilization of HBsAg positive liver grafts did not increase the incidence of early-stage complications. However, patient with an HBsAg-positive graft had poorer progression-free survival and overall survival.

Exploration of Optimal pH in Hypothermic Machine Perfusion for Rat Liver Grafts Retrieved after Circulatory Death

Ex vivo hypothermic machine perfusion (HMP) is a strategy for controlling ischemia-reperfusion injury in donation after circulatory death (DCD) liver transplantation. The pH of blood increases with a decrease in temperature and water dissociation, leading to a decrease in [H⁺]. This study aimed to verify the optimal pH of HMP for DCD livers. Rat livers were retrieved 30 min post-cardiac arrest and subjected to 3-h cold storage (CS) in UW solution (CS group) or HMP with UW-gluconate solution (machine perfusion [MP] group) of pH 7.4 (original), 7.6, 7.8, and 8.0 (MP-pH 7.6, 7.8, 8.0 groups, respectively) at 7-10 °C. The livers were subjected to normothermic perfusion to simulate reperfusion after HMP. All HMP groups showed greater graft protection compared to the CS group due to the lower levels of liver enzymes in the former. The MP-pH 7.8 group showed significant protection, evidenced by bile production, diminished tissue injury, and reduced flavin mononucleotide leakage, and further analysis by scanning electron microscopy revealed a well-preserved structure of the mitochondrial cristae. Therefore, the optimum pH of 7.8 enhanced the protective effect of HMP by preserving the structure and function of the mitochondria, leading to reduced reperfusion injury in the DCD liver.

The Current Role and Future Applications of Machine Perfusion in Liver Transplantation

The relative paucity of donor livers suitable for transplantation has sparked innovations to preserve and recondition organs to expand the pool of transplantable organs. Currently, machine perfusion techniques have led to the improvement of the quality of marginal livers and to prolonged cold ischemia time and have allowed for the prediction of graft function through the analysis of the organ during perfusion, improving the rate of organ use. In the future, the implementation of organ modulation might expand the scope of machine perfusion beyond its current usage. The aim of this review was to provide an overview of the current clinical use of machine perfusion devices in liver transplantation and to provide a perspective for future clinical use, including therapeutic interventions in perfused donor liver grafts.

Caspase 6/NR4A1/SOX9 signaling axis regulates hepatic inflammation and pyroptosis in ischemia-stressed fatty liver

The mechanism of nonalcoholic fatty liver susceptibility to ischemia/reperfusion (IR) injury has not been fully clarified. Caspase 6 is a critical regulator in innate immunity and host defense. We aimed to characterize the specific role of Caspase 6 in IR-induced inflammatory responses in fatty livers. Human fatty liver samples were harvested from patients undergoing ischemia-related hepatectomy to evaluate Caspase 6 expression. in mice model, we generated Caspase 6-knockout (Caspase 6^KO) mice to investigate cellular and molecular mechanisms of macrophage Caspase 6 in IR-stimulated fatty livers. In human liver biopsies, Caspase 6 expression was upregulated combined with enhanced serum ALT level and severe histopathological injury in ischemic fatty livers. Moreover, Caspase 6 was mainly accumulated in macrophages but not hepatocytes. Unlike in controls, the Caspase 6-deficiency attenuated liver damage and inflammation activation. Activation of macrophage NR4A1 or SOX9 in Caspase 6-deficient livers aggravated liver inflammation. Mechanistically, macrophage NR4A1 co-localized with SOX9 in the nuclear under inflammatory conditions. Specifically, SOX9 acts as a coactivator of NR4A1 to directly target S100A9 transcription. Furthermore, macrophage S100A9 ablation dampened NEK7/NLRP3-driven inflammatory response and pyroptosis in macrophages. In conclusion, our findings identify a novel role of Caspase 6 in regulating NR4A1/SOX9 interaction in response to IR-stimulated fatty liver inflammation, and provide potential therapeutic targets for the prevention of fatty liver IR injury.

A Retrospective Evaluation of Changing Health Characteristics Amongst Deceased Organ Donors in the United States

BACKGROUND

The availability of suitable donor organs remains a limiting factor to performing life-saving transplant operations. This study evaluates changes in the health of the donor population and its influence on organ use in the United States.

METHODS

A retrospective analysis was performed using the OPTN STAR data file from 2005 to 2019. Three donor eras were defined: 1) 2005 to 2009, 2) 2010 to 2014, and 3) 2015 to 2019. The primary outcome was donor use, defined as transplantation of at least one solid organ. Descriptive analyses were performed, and associations of donor use were examined with multivariable logistic regression models. P values <.01 were considered significant.

RESULTS

The cohort included 132,783 potential donors of which 124,729 (93.9%) were used for transplantation. Donor median age was 42 years (interquartile range 26-54), 53,566 (40.3%) were female, and 88,209 (66.4%) were White, 21,834 (16.4%) were black, and 18,509 (13.9%) were Hispanic. Compared with donors from Eras 1 and 2, donors in Era 3 were younger (P < .001), had higher body mass index (BMI) (P < .001), increased rates of diabetes mellitus (DM) (P < .001), hepatitis C virus (HCV) positivity (P < .001) and more comorbidities (P < .001). Multivariable modeling found donor BMI, DM, hypertension, and HCV status as health factors significantly associated with donor use. Compared with Era 1, there was increased use in Era 3 of donors with BMI ≥30 kg/m², DM, hypertension, HCV-positive status, and donors with ≥3 comorbidities.

CONCLUSIONS

Despite an increasing prevalence of chronic health problems in the donor population, donors with multiple comorbid conditions are more likely to be used for transplantation in recent years.