The acylcarnitine (AC) profile has been shown to be altered in survivors of a prolonged stay in intensive care unit (ICU), with higher short-chain derivates compared to reference ranges. The present study aimed at describing the AC profile of patients surviving a short ICU stay versus patients surviving a >7-day multiple organ dysfunction. Patients discharged from ICU after an elective and non-complicated cardiac surgery (CS) were recruited. For each CS, one to two adults, matched for gender and age, were recruited among patients enrolled in our post-ICU follow-up program after an ICU stay ≥7 days (PS). In both groups, the AC profile was determined during the week following ICU discharge. A total of 50 CS patients (SAPS II 23 (18–27)) survived an ICU stay of 2 (2–3) days and were matched to 85 PS patients (SAPS II 36 (28–51), p < 0.001) who survived an ICU stay of 11 (8–15.5) days. No carnitine deficiency was observed in either group. Their total AC/C0 ratio was similar: 0.355 (0.268–0.415) and 0.358 (0.289–0.417), respectively (p = 0.391). A ratio >0.4 representing a disturbed mitochondrial metabolism was observed in 26/85 (30.6%) PS patients and in 15/50 (30%) CS patients (p > 0.999). The long-chain ACs were elevated in both groups, with a greater increase in the CS group. The short-chain ACs were higher in the PS group: 1.520 (1.178–1.974) vs. 1.185 (0.932–1.895) μmol/L (p < 0.001). The role of the AC profile as potential marker of catabolism and/or mitochondrial dysfunction during the critical illness trajectory should be further investigated.

In chronic liver diseases (CLD), when native hepatocytes enter replicative senescence, new hepatocytes are produced via differentiation of reactive cholangiocytes, also known as ductular reaction - DR - cells. However, this mechanism alone is insufficient to prevent liver failure, emphasizing the need for a deeper understanding to enhance its therapeutic potential. We hypothesize that signals driving DR differentiation into hepatocytes reside in the local niche, particularly extracellular matrix (ECM) composition and neighboring cells. We modeled CLD in mice using CCl₄ injections (3x/week for 6 weeks). Using Opn-iCreERT2; Rosa26RYFP mice, we tracked DR fate, and with Cdh5-iCreERT2; Rosa26RmT/mG mice, we studied LSEC origins. Mouse liver tissues were analyzed using immunohistochemistry (IHC), flow cytometry, RT-qPCR and RESOLVE molecular cartography for spatial transcriptomic. Double-spheroids were used to study ECM effect in vitro. We examined human liver tissues with double IHC and publicly available scRNA-seq datasets were used. We identified two populations of ductular reaction (DR) cells: those surrounded by laminin (Lam-DRs) and those without laminin (NoLam-DRs). Lam-DRs retained a biliary phenotype, while NoLam-DRs showed increased Hnf4α expression. In vitro, a laminin-rich environment maintained cholangiocyte-specific gene expression, supporting laminin's role in preserving the biliary phenotype. Lam-DRs were closely associated with capillarized CD34+ LSECs, which expressed profibrotic and laminin-related genes. Preventing LSEC capillarization reduced laminin deposition and enhanced DR-to-hepatocyte differentiation in chronically injured mice. The CD34+ LSECs-Laminin-DR complex was also present in human liver disease samples. Capillarized CD34+ LSECs maintain the biliary phenotype of DR cells by preventing laminin degradation, thereby limiting their differentiation into hepatocytes. Targeting this axis could enhance liver regeneration and improve outcomes in chronic liver disease. Chronic liver disease progression is characterized by impaired hepatocyte regeneration, making alternative regenerative pathways such as DR-driven hepatocyte formation of particular interest. This study provides mechanistic insight into how the local microenvironment specifically capillarized CD34⁺ LSECs and laminin deposition restricts DR plasticity by stabilizing a biliary fate, thereby limiting endogenous regeneration. These findings are relevant for researchers investigating liver regeneration, fibrosis, and cholangiopathies, and for clinicians seeking to understand why regenerative responses remain inefficient in advanced disease. While acknowledging that DR-derived hepatocytes contribute modestly to overall parenchymal renewal, our results suggest that therapeutically modulating LSEC capillarization or ECM remodeling could represent a strategy to enhance regenerative competence in chronic liver disease, warranting further preclinical and translational investigation.