Volume 143, Issue 3, Pages 544-549.e2 (September 2012) Direct Molecular Tissue Analysis by MALDI Imaging Mass Spectrometry in the Field of Gastrointestinal Disease  Benjamin Balluff, Sandra Rauser, Matthias P. Ebert, Jens T. Siveke, Heinz Höfler, Axel Walch  Gastroenterology  Volume 143, Issue 3, Pages 544-549.e2 (September 2012) DOI: 10.1053/j.gastro.2012.07.022 Copyright © 2012 AGA Institute Terms and Conditions

Figure 1 MALDI imaging is able to analyze even the smallest tissue samples from patients, such as endoscopic biopsies, which are readily collectable in a gastroenterological setting. The subsequent histology-directed and unlabeled analysis allows to extract spatially resolved, cell type-specific molecular signatures from a wide variety of molecule classes and to correlate them with clinical endpoints. These patterns may, therefore, directly support the clinician in relevant questions such as in tissue diagnostics, therapy response prediction, or disease outcome prediction. Gastroenterology 2012 143, 544-549.e2DOI: (10.1053/j.gastro.2012.07.022) Copyright © 2012 AGA Institute Terms and Conditions

Figure 2 For MALDI imaging/profiling, a tissue section is placed onto a glass slide before matrix application. Whereas imaging experiments require the section to be densely covered by matrix, matrix is applied to selected spots only in profiling. After MALDI-MS measurements of the spots or grid points, the matrix can be removed. The very same tissue section may then be stained and digitally co-registered to the spatially resolved MS data. This facilitates investigating the distributions of single m/z signals within the section's histology, statistically analyzing data set, or extracting histology-specific molecular profiles. Gastroenterology 2012 143, 544-549.e2DOI: (10.1053/j.gastro.2012.07.022) Copyright © 2012 AGA Institute Terms and Conditions

Figure 3 Castellino et al13 used MALDI imaging to study the histopharmacology of several lapatinib metabolites in dog liver tissue sections at both, high optical (A) and high mass resolution (B). A high optical resolution (50 μm) allowed locating heme in the portal veins, a lapatinib metabolite (GSK042) in the bile ducts, and an endogenous species in the surrounding connective tissue (A). A high mass resolution, achieved by Fourier transform mass spectrometry (FTMS), allowed separating 2 metabolites (GW006 and M2) of lapatinib with nearly identical masses, but distinct spatial localizations. (Reproduced and adapted from Castellino et al,13 with permission of Future Science Ltd.) Gastroenterology 2012 143, 544-549.e2DOI: (10.1053/j.gastro.2012.07.022) Copyright © 2012 AGA Institute Terms and Conditions

Supplemental Figure 1 In one of our studies, MALDI imaging was performed in intestinal-type gastric cancer tissues for the discovery of novel prognostic protein markers.7 A 7-protein signature was found that correlated with the overall survival of patients (A). Clustering of the patients according to this pattern (B) resulted in groups with good and poor prognosis (C). The visualization of one of the prognostic signals, such as from CRIP1 (E), showed a significant higher expression in tumor (D, red) than in healthy stomach mucosa (D, green). Gastroenterology 2012 143, 544-549.e2DOI: (10.1053/j.gastro.2012.07.022) Copyright © 2012 AGA Institute Terms and Conditions