Mass spectrometry-based spatiotemporal characterization of lipids in early focal cerebral ischemia

Understanding spatial lipid alterations in the brain during the hyper-acute phase of acute ischemic stroke (AIS) is crucial for elucidating the underlying mechanisms of disease progression and therapeutic response. In this study, we employed an integrated approach combining matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and pseudo-targeted lipidomics to characterize lipid changes in the mice brain after 1 h, 2 h, and 3 h of middle cerebral artery occlusion (MCAO). Remarkably, MALDI-MSI detected significant lipid alterations in ischemic brain regions as early as 1 h post-MCAO, preceding visible tissue infarction by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Lipidomics analysis further revealed region-specific lipid alterations at this early time point, suggesting that lipid profiles may serve as more sensitive biomarkers of ischemic brain injury than conventional histopathological methods. Notably, both MSI and lipidomics analysis demonstrated consistent temporal progression of lipid changes. Significantly altered lipids exhibited a nearly identical increasing trend with prolonged ischemic duration, with the ischemic cortex showing the most pronounced lipid dysregulation. In conclusion, our findings demonstrate that MALDI-MSI coupled with lipidomics provides a comprehensive platform for mapping the dynamic lipid landscape in the ischemic brain during early AIS, with observed patterns well correlating with the expansion of tissue infarction.