A Guide to MALDI Imaging Mass Spectrometry for Tissues

Abstract

Imaging mass spectrometry is a well-established technology that can easily and succinctly communicate the spatial localization of molecules within samples. This review communicates the recent advances in the field, with a specific focus on matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) applied on tissues. The general sample preparation strategies for different analyte classes are explored, including special considerations for sample types (fresh frozen or formalin-fixed,) strategies for various analytes (lipids, metabolites, proteins, peptides, and glycans) and how multimodal imaging strategies can leverage the strengths of each approach is mentioned. This work explores appropriate experimental design approaches and standardization of processes needed for successful studies, as well as the various data analysis platforms available to analyze data and their strengths. The review concludes with applications of imaging mass spectrometry in various fields, with a focus on medical research, and some examples from plant biology and microbe metabolism are mentioned, to illustrate the breadth and depth of MALDI IMS.

Mass spectrometry imaging for spatially resolved multi-omics molecular mapping

“…Thus, powerful data analysis platforms are demanded for MSI. A detailed review of MSI data analysis has been given elsewhere 32 , 113 , 114 , here we focus on the recent advancements in MSI data analysis.…”

“…Commercially available software packages can be used for MS imaging data analysis, but there are also free software options 32 . One widely used data analysis platform is MSiReader, which was created with MATLAB 115 .…”

“…The choice of matrix is crucial as it can affect the detection sensitivity, spatial resolution, and types of molecules that can be ionized efficiently during MALDI-MSI experiments. In addition to conventional MALDI matrices like α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxy benzoic acid (DHB), and 3,5-dimethoxy-4-hydroxycinnamic acid (sinapic acid), a variety of novel matrices have been developed for MALDI-MS imaging with enhanced sensitivity and molecule coverage 32 – 35 . Moreover, the optics system in MALDI-MS imaging is undergoing rapid development to achieve higher spatial resolution and improved ionization efficiency.…”