Metabolic Niches: MALDI Imaging Reveals Lipidomic Heterogeneity in the Human Heart

The human heart is characterized by aberrant lipid accumulation and remodeling during periods of stress and disease, yet spatially resolved lipidomic profiling of the human heart remains unreported. Here, we employ matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to map lipid distributions across five anatomical regions of healthy human donor hearts (left and right atrium, left and right ventricle, and interventricular septum). Cryosections of donor hearts from healthy subjects were thaw-mounted onto indium tin oxide slides, coated with 2,5-dihydroxyacetophenone, and analyzed on a Bruker timsTOF fleX mass spectrometer in positive and negative ionization modes (m/z 50–1850; 20 μm raster spacing). Serial sections were stained with hematoxylin and eosin to enable histological coregistration with lipid distributions. We identified 150 unique lipid species across four glycerophospholipid classes, including phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), and phosphatidylserine (PS), with abundances and spatial distributions differing significantly between regions. H&E coregistration further resolved epicardial and myocardial compartments, enabling tissue-specific lipid mapping. These findings establish the first spatially resolved lipidomic profiles of the human heart and provide a framework for identifying region-specific lipid biomarkers of cardiovascular disease.