Abstract
Matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS; also referred to as mass spectrometry imaging; MSI) enables the visualization of the distribution of a range of biomolecules that have varied structures in the cells and tissue sections. This emerging imaging technique was initially developed as a tool for protein imaging, but recently it is increasingly being used for the imaging of small organic molecules. IMS is an effective technique for the imaging of small metabolites, including endogenous metabolites such as lipids and exogenous drugs because of the following advantages: First, IMS does not require any specific labels or probes. Second, IMS is a non-targeted imaging method. Finally, the simultaneous imaging of many types of metabolite molecules is possible, and all these features are necessary for the assessment of metabolite localization. In this review, we discuss the capability of current IMS techniques for imaging small molecules, and introduce representative studies on imaging of endogenous and exogenous metabolites. In addition, the limitations and problems of the technique are also discussed, and reports of progress toward solving the problems with this technique are also introduced.
