Dataset Information

Improved MALDI-MS Imaging of Polar and 2H-Labeled Metabolites in Mouse Organ Tissues

ABSTRACT: Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is an indispensable analytical tool to depict the spatial distribution of analytes such as polar metabolites, lipids, proteins, and drugs in biological specimens. Imaging small polar metabolites and analyzing their in-vivo dynamics with stable isotope labeled (SIL) tracing through various biochemical pathways, including citric acid (TCA) cycle, glycolysis, and amino acid metabolism, has gained substantial interest over the years. However, imaging these polar metabolites across different tissue types is limited due to their lower ionization efficiencies and ion suppression from other abundant biomolecules. These challenges can be further exacerbated with SIL studies, which require the improvement of sample preparation methods. Solvent pretreatments before matrix application on a tissue section have the potential to improve the sensitivity, but often challenges with validation of spatial distribution of metabolites revealed in MALDI-MSI. Here, we present a optimized 'basic hexane' wash method that improved the detection of small molecules with exceptional sensitivity up to several folds for polar and 2H labeled glycolytic metabolites across five different mouse organ tissues (kidney, heart, brain, liver, and brown adipose tissue). Further, we addressed one of the major concerns such as validation of localised polar metabolites within the tissue regions by implementing spatial validation workflow. The workflow depicts the use of region of interest guided laser capture microdissection of tissue regions followed by LC-MS/MS. Indeed, majority of metabolites showed an excellent corroboration with distribution of metabolites in MALDI-MSI and LMD-LC-MS/MS. Besides, we also observed the similar effect on boosting signal intensities of polar metabolites extracted from the microsampled tissues using LMD followed by LC-MS/MS. Overall, we provided an improved MALDI sample pretreatment approach and the spatial validation workflow to understand polar metabolite distribution in mouse organs.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (ncbitaxon:10090)

SUBMITTER: Dr. Prasad Phapale