Tissue Preparation for Spatial Metabolomics v1

摘要

Mass spectrometry imaging (MSI) is a cutting-edge molecular technology that enables simultaneous analysis of multiple molecular components directly from single cells, tissues, and organs. For MSI, cryosections are prepared from flash-frozen tissue and mounted on a contuctive glass slide. We use matrix-assisted laser desorption ionization (MALDI)-MSI, where tissue sections are coated with a MALDI matrix in order to facilitate laser ionization and detection of metabolites with mass spectrometry. We do it using an automated robotic sprayer (TM-Sprayer) with 2,5- dihydroxybenzoic acid (DHB) MALDI matrix for positive ion mode analysis, N-(1-naphthyl) ethylenediamine hydrochloride (NEDC) for negative ion mode analyses, or 1,5-Diaminonaphthalene (DAN) for dual-polarity analysis, prior to being loaded into the MALDI-Q Exactive HF-X Orbitrap-MSI or MALDI-FTICR-MSI for untargeted metabolomics analysis. We have optimized a method for matrix application to maximize analyte extraction from tissue and increase MALDI sensitivity and to create the most homogenous matrix films possible for best lateral resolution of lipids. A key capacity that will be critical for scale-up in KPMP is the use of a TM-sprayer robotic sprayer for MALDI matrix application. This will make inter-lab studies viable, by increasing the reproducibility of sample preparation and is currently in use at UTHSA and PNNL. Our lipid extraction protocol for LC-MS/MS is a robust and universal protocol for single-sample integrative proteomics, metabolomics, and lipidomics analyses (see citation).