MALDI mass spectrometric imaging meets “omics”: recent advances in the fruitful marriage

Abstract

Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI MSI) is a method that allows the investigation of the molecular content of surfaces, in particular, tissues, within its morphological context. The applications of MALDI MSI in the field of large-scale mass spectrometric studies, which are typically denoted by the suffix "omics", are steadily increasing. This is because, on the one hand, technical advances regarding sample collection and preparation, matrix application, instrumentation, and data processing have enhanced the molecular specificity and sensitivity of MALDI MSI; on the other hand, the focus of the "omics" community has moved from establishing an inventory of certain compound classes to exploring their spatial distribution to gain novel insights. Thus, the aim of this mini-review is twofold, to display the state-of-the-art in terms of technical aspects in MALDI MSI and to highlight selected applications in the last two years, which either have significantly advanced a certain "omics" field or have introduced a new one through pioneering efforts.

Tracing the fate and transport of secondary plant metabolites in a laboratory mesocosm experiment by employing mass spectrometric imaging

“…Preliminary data were obtained by testing a variety of different matrices typically employed for the MALDI-TOF MSI analysis of metabolites [6], such as DHB, dithranol, and 1,5-DAN in the positive and negative reflector mode, respectively. However, only the simplest sample preparation by leaving out the matrix application enabled us to use a spatial resolution of 50 μm, additionally, this technique prevented the delocalization of the studied compounds, which was observed, in particular when DHB was sprayed with an air-brush device on top of the grasshopper longitudinal section.…”

“…The idea was to follow the abundance and compositional change of organic substances along a plant-herbivore-excretions (feces)-soil solution pathway by the application of emerging visualization techniques, namely laser desorption/ionization time-of-flight mass spectrometric imaging (LDI-TOF MSI) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometric imaging (MALDI-TOF MSI) [6, 7]. The latter technique requires the evaluation of suitable matrices for the analysis of secondary plant metabolites [8, 9], in particular when different objects (grass leaves, grasshopper, excrements) are analyzed.…”

Laser capture microdissection in combination with mass spectrometry: Approach to characterization of tissue-specific proteomes ofEudiplozoon nipponicum(Monogenea, Polyopisthocotylea)

“…With respect to investigation of the molecular content of the tissue within its morphological context, it was the technique of mass spectrometry imaging (MSI) that made it possible [24]. In parasitology, one study examined the chemical markers of the surface of S. mansoni by MSI to distinguish between the sexes and the strains [25], while another study dealt with the same organism and investigated the composition of internal organs by histological sections [26].…”

Infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging analysis of biospecimens

“…Mass spectrometry imaging (MSI) is a rapidly evolving technique applied to a wide variety of applications from proteins 1 , pharmaceuticals 2 , endogenous metabolites 3 , and –omic level analysis 4 . In MSI, there are two general modes of operation - microscope and microprobe 5 .…”