Background & Aims: Liver fibrosis is a pathological healing process resulting from hepatic stellate cell (HSC) activation and the generation of myofibroblasts from activated HSCs. The precise underlying mechanisms of liver fibrogenesis are still largely vague due to lack of understanding the functional heterogeneity of activated HSCs during liver injury. Approach and Results: In this study, to define the mechanism of HSC activation, we performed the transcriptomic analysis at single-cell resolution (scRNA-seq) on HSCs in mice treated with carbon tetrachloride (CCl₄). By employing LRAT-Cre:Rosa26^mT/mG mice, we were able to isolate an activated GFP-positive HSC lineage derived cell population by fluorescence-activated cell sorter (FACS). A total of 8 HSC subpopulations were identified based on an unsupervised analysis. Each HSC cluster displayed a unique transcriptomic profile, despite all clusters expressing common mouse HSC marker genes. We demonstrated that one of the HSC subpopulations expressed high levels of mitosis regulatory genes, velocity, and monocle analysis indicated that these HSCs are at transitioning and proliferating phases at the beginning of HSCs activation and will eventually give rise to several other HSC subtypes. We also demonstrated cell clusters representing HSC-derived mature myofibroblast populations that express myofibroblasts hallmark genes with unique contractile properties. Most importantly, we found a novel HSC cluster that is likely to be critical in liver regeneration, immune reaction, and vascular remodeling, in which the unique profiles of genes such as Rgs5, Angptl6, and Meg3 are highly expressed. Lastly, we demonstrated that the heterogeneity of HSCs in the injured mouse livers is closely similar to that of cirrhotic human livers. Conclusions: Collectively, our scRNA-seq data provided insight into the landscape of activated HSC populations and the dynamic transitional pathway from HSC to myofibroblasts in response to liver injury.

Background: The association between hepatic ischemia-reperfusion injury (hIRI) in steatotic livers and subsequent acute kidney injury (AKI) is well established. Ferroptosis plays a critical role in fatty liver IRI. However, whether ferroptosis also contributes to secondary AKI following hIRI remains unclear. Methods: hIRI was induced in mice fed either a high-fat, high-sucrose diet (HFD) or a normal diet (ND) to mimic the AKI commonly observed clinically after fatty liver transplantation. Kidney injury mechanisms were evaluated using histopathology, RNA sequencing, electron microscopy, and biochemical assays. Ferroptosis in the kidney was assessed by quantifying ACSL4, 4-hydroxynonenal (4-HNE), and AA-PE in homogenates and tissue sections. In parallel experiments, the lipid peroxidation inhibitor Liproxstatin-1 (Lip-1) was administered prior to hIRI to inhibit ferroptosis. Results: AKI severity was markedly increased in HFD-fed mice compared to ND controls following hIRI. Histological, transcriptomic, and cytokine analyses revealed that apoptosis and inflammation were the primary mechanisms of kidney injury after HFD + hIRI. Kidney levels of ACSL4 and 4-HNE were not significantly elevated in either group after hIRI. Lip-1 treatment significantly reduced both liver injury and AKI in HFD-fed mice but showed no protective effect in ND-fed animals. Conclusion: Apoptosis and inflammation are the prominent kidney injury mechanisms involved in AKI following fatty liver IRI. Although ferroptosis may not be directly involved in the renal injury, anti-ferroptotic intervention mitigates AKI, supporting the concept that ferroptosis-mediated liver injury may serve as the primary upstream trigger in this context.

Background.: In 2020, liver allocation policy in the United States was changed to allow for broader organ sharing, which was hypothesized to reduce patient incentives to travel for transplant. Our objective was to describe patterns of travel for domestic liver transplant pre- and post–acuity circle (AC) implementation. Methods.: Incident adult liver transplant listings between August 16, 2016, and February 3, 2020 (pre-AC) or June 13, 2020, and December 3, 2023 (post-AC) were obtained from the Scientific Registry of Transplant Recipients. We used previously defined geographic catchment areas to classify patients as (1) no travel, (2) travel to a neighboring region, and (3) travel beyond a neighboring region. We used multinomial logistic regression to identify characteristics associated with travel and cause-specific hazards modeling to estimate the association between travel and time to deceased donor transplant, stratified by model for end-stage liver disease (MELD) score and AC era. Results.: Among 83 033 liver candidates, 76% were listed in their home region. Black race, lower educational attainment, increased neighborhood social deprivation, and Medicaid were significantly associated with decreased odds of traveling beyond a neighboring region. After AC, traveling beyond a neighboring region was associated with an increased hazard of transplant for patients with a MELD score <15 (cause-specific hazard ratio [csHR]: 1.25; 95% confidence interval [CI], 1.11-1.40), MELD score 15–24 (csHR: 1.19; 95% CI, 1.07-1.31), and MELD score 25–34 (csHR: 1.15; 95% CI, 1.01-1.32). Conclusions.: Travel frequency, geographic patterns of travel, and characteristics associated with travel were largely unchanged after AC. Changes to allocation policy alone may not equalize patient means or desire to travel for transplant care.