Untargeted red blood cell metabolomics reveals distinct metabolic signatures in malignant cerebral edema following acute ischemic stroke

Malignant cerebral edema (MCE) is a major cause of mortality and disability in acute ischemic stroke, yet effective treatments remain limited. Early identification of patients at high risk for MCE is therefore an important unmet clinical need. Patients with large vessel occlusion acute ischemic stroke (LVO-AIS) were prospectively enrolled. All patients had radiologically confirmed LVO and underwent follow-up neuroimaging for cerebral edema assessment. MCE was defined as cerebral edema grade 3 (CED-3) on the Thrombolysis in Stroke–Monitoring Study edema scale, while non-MCE was defined as CED-1–2. In a pilot screening phase, plasma, red blood cell (RBC), and urine samples were collected on days 1, 3, and 7 after stroke onset from a subset of patients to identify the most informative biofluid and sampling time point. Based on these results, untargeted metabolomic profiling using ultrahigh-performance liquid chromatography–tandem mass spectrometry was performed in RBC samples collected within 24 h of stroke onset from an expanded cohort. Pilot screening (n = 3 per group) indicated that day 1 RBC samples showed the most pronounced metabolic differences between patients who later developed MCE and those who did not. Accordingly, day 1 RBCs from 61 patients (19 MCE, 42 non-MCE) were analyzed. Untargeted metabolomic analysis identified 521 differentially abundant metabolites, including 177 upregulated and 344 downregulated features in the MCE group. Key altered metabolites included palmitoylethanolamide, S-adenosylmethionine, and spermidine, with enrichment in pathways related to cofactor biosynthesis, neuroactive ligand–receptor interactions, and amino acid metabolism. Red blood cell metabolomic profiles within 24 h of stroke onset differ between patients who subsequently develop malignant cerebral edema and those who do not. These findings provide exploratory insights into early metabolic alterations associated with MCE and warrant further validation in larger, targeted studies.