Marginal donor liver versus standard donor liver: A single center-observational study

Advances in Subclinical and Clinical Trials and Immunosuppressive Therapies in Xenotransplantation

Organ transplantation remains the foremost effective intervention for end-stage organ failure. Nevertheless, the scarcity of donors has resulted in prolonged waiting times for countless patients globally. The advent of xenografts presents a promising solution to the organ shortage crisis. Although the utilization of xenografts has a long history, it is only in recent years that breakthroughs in genetically modified pigs have rendered successful xenotransplantation a feasible option. In the past 4 years, numerous subclinical and clinical trials have involved xenotransplantation from genetically modified pigs to humans. However, the outcomes have been disappointing, necessitating a reassessment of basic and preclinical research to address the emerging challenges. Furthermore, immunosuppressive therapies remain essential in xenotransplantation. The range of immunosuppressive agents, encompassing traditional immunosuppressants and monoclonal antibodies such as anti-CD154/CD40 monoclonal antibodies, exhibits considerable diversity. However, the most effective drug combination for achieving optimal efficacy remains elusive. This review will offer a succinct overview of the results from recent clinical and subclinical xenotransplantation trials. Moreover, it will highlight recent advancements in immunosuppressive strategies and discuss potential future research directions in this field.

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.

LXRα agonists ameliorates acute rejection after liver transplantation via ABCA1/MAPK and PI3K/AKT/mTOR signaling axis in macrophages

INTRODUCTION

Liver X receptor α (LXRα) plays an important role in inflammatory immune response induced by hepatic ischemia-reperfusion injury (IRI) and acute rejection (AR). Macrophage M1-polarization play an important role in the occurrence and development of AR. Although the activation of LXR has anti-inflammatory effects, the role of LXRα in AR after liver transplantation (LT) has not been elucidated.

OBJECTIVE

We aimed to investigate LXRα anti-inflammatory and macrophage polarization regulation effects and mechanisms in acute rejection rat models.

METHODS

LXRα anti-inflammatory and liver function protective effects was initially measured in primary Kupffer cells and LT rat models. Subsequently, a flow cytometry assay was used to detect the regulation effect of LXRα in macrophage polarization. HE staining, TUNEL and ELISA were used to evaluate the co-treatment effects of TO901317 and tacrolimus on hepatic apoptosis and liver acute rejection after LT.

RESULTS

In this study, we found that LPS can inhibit the expression of LXRα and activate MAPK pathway and PI3K/AKT/mTOR. We also found that LXRα agonist (TO901317) could improve liver function and rat survival after LT by activating the level of ABCA1 and inhibiting MAPK. TO901317 could inhibit macrophage M1-polarization by activating PI3K/AKT/mTOR signal pathway to improve the liver lesion of AR rats after liver transplantation. Additionally, co-treatment with TO901317 and tacrolimus more effectively alleviated the damaging effects of AR following LT than either drug alone.

CONCLUSION

Our results suggest that the activation of LXRα can improve liver function and rat survival after LT by regulate ABCA1/MAPK and PI3K/AKT/mTOR signaling axis in macrophages.

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.

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.