Background: Outcomes after critical illness vary markedly despite similar diagnoses and severity scores, underscoring the limitations of chronological age and conventional Intensive Care Unit (ICU) prognostic tools. Personalization of critical care is increasingly essential to improve not only short-term survival but also long-term post-discharge outcomes. Biological aging clocks provide a quantitative framework to capture physiological reserve, immune competence, and vulnerability to stress. Methods: We conducted a scoping review of original human studies published between January 2015 and October 2025 that evaluated biological aging biomarkers in adult ICU populations. PubMed/MEDLINE, Scopus, Web of Science, and Embase were searched, with backward citation screening. Results: Across epigenetic, telomere-based, cfDNA, proteomic, metabolomic, and phenotypic aging measures, accelerated biological aging was consistently associated with increased mortality, organ dysfunction, and post-ICU vulnerability. Despite substantial methodological heterogeneity, a convergent signal emerged linking inflammation-weighted and stress-responsive deep biological clocks to clinically meaningful outcomes in critically ill patients. Conclusions: Biological aging biomarkers represent a mechanistically grounded approach to personalized prognostication in critical care. From a translational perspective, deep biological clocks hold promise for personalized risk stratification, prognostication, and the identification of high-risk recovery phenotypes, although prospective validation and implementation studies are required.

Background.: Split liver transplantation (SLT) maximizes donor organ utilization but faces challenges with ischemia-reperfusion injury (IRI). Machine perfusion techniques, including hypothermic oxygenated perfusion (HOPE), dual HOPE (DHOPE), and normothermic machine perfusion (NMP), may enhance graft viability and expand the donor pool. This scoping review maps existing clinical and experimental evidence on machine perfusion in SLT, examining benefits, feasibility, outcomes, and knowledge gaps. Methods.: Following Joanna Briggs Institute manual guidelines, we searched PubMed, Embase, Scopus, and Web of Science through September 3, 2025, plus gray literature (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, Google Scholar). Studies exploring machine perfusion techniques in liver splitting of human or animal grafts, with or without transplantation, were included. Results.: After screening 958 records, 38 studies were included (29 primary studies, 9 reviews). Among primary studies, 84 clinical transplant cases using machine perfusion were identified (including 2 cases with unspecified perfusion modality); however, this number may not represent unique patients because of possible overlap between same-center cohorts. HOPE (7 studies, 40 cases) was supported by preliminary comparative data suggesting reduced IRI versus static cold storage, with 1 cohort study showing lower postreperfusion syndrome rates (13.3% versus 47.1%, P = 0.04) and reduced IRI scores (3 versus 4, P = 0.03). NMP (16 studies, 34 cases) enabled extended preservation up to 25 h with 100% short-term graft survival in case series. DHOPE (4 studies, 8 cases) reported feasibility for complex full-left/full-right splitting. Evidence was limited by small sample sizes (median n = 2, range 1–26), short follow-up (maximum 18 mo, median 6 mo), absence of randomized trials, and potential publication bias. Conclusions.: Machine perfusion remains an investigational strategy in SLT. Preliminary evidence suggests HOPE may reduce IRI and NMP may provide logistical advantages through extended preservation. However, evidence derives entirely from small observational studies without randomization. Multicenter prospective studies with standardized protocols, longer follow-ups, and cost-effectiveness analyses are needed.