Development of an Imaging Mass Spectrometry Technique for Visualizing Localized Cellular Signaling Mediators in Tissues

Abstract

In vivo concentrations of cellular signaling mediators such as in ammatory mediators are normally maintained at very low levels due to their strong ability to induce a biological response. e production, di usion, and decomposition of such mediators are spatio-temporally regulated. erefore, in order to understand biochemical basis of disease progression and develop new therapeutic strategies, it is important to understand the spatiotemporal dynamics of the signaling mediators in vivo, during the progression of disorders, e.g., chronic in ammatory diseases; however, the lack of e ective imaging technology has made it di cult to determine their localizations in vivo. Such characterization requires technical breakthroughs, including molecular imaging methods that are sensitive enough to detect low levels of metabolites in the heterogeneous tissue regions in diseased organs. We and other groups have attempted to ll this technical gap by developing highly sensitive imaging mass spectrometry (IMS) technologies. To date, we have established two key techniques toward this goal, including (i) a sample preparation procedure that has eliminated the problem of the postmortem degradation of labile metabolites, and (ii) on-tissue derivatization of metabolites, which can enhance analyte ionization e ciency. Here, we review recent progress in the development of these technologies as well as how the highly sensitive IMS technique has contributed to increasing understanding of the biochemical basis of disease mechanisms, discovery of new diagnostic markers, and development of new therapies.Please cite this article as: Mass Spectrom (Tokyo) 2015; 4(1): A0040

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“…Transcranial light illumination for optogenetic stimulation of neurons or astrocytes was executed as before. Thirty seconds after the stimulation, was applied for 0.92 s to the head of the mouse to rapidly inactivate enzymatic reactions in the brain, which minimizes postmortem alterations in metabolites during brain extraction (Sugiura et al, ). Brains were then extracted, frozen, and sliced coronally at a thickness of 8 μm.…”

“…Fifteen minutes later (Sugiura et al, ), optogenetic stimulation of the left cortex through the intact skull was performed. Thirty seconds later, mice were euthanized by FMW‐irradiation for 0.96 s on the brain (Sugiura, Honda, & Suematsu, ). Matrix‐assisted laser desorption ionization (MALDI)‐IMS was performed on thin sections of the brain.…”

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Profiling Cell Signaling Networks at Single-cell Resolution

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