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Updated: Aug 14, 2025
Whole-body Mass Spectrometry Imaging by Infrared Matrix-assisted Laser Desorption Electrospray Ionization IR-MALDESI
Published on: March 24, 2016
MALDI-IHC-Guided In-Depth Spatial Proteomics: Targeted and Untargeted MSI Combined
Britt S R Claes1, Kasper K Krestensen1, Gargey Yagnik2
1The Maastricht MultiModal Molecular Imaging (M4I) institute, Division of Imaging Mass Spectrometry (IMS), Maastricht University, 6229 ER Maastricht, The Netherlands.
A new MALDI-IHC technique combines mass spectrometry imaging and immunohistochemistry for multiplexed biomolecule analysis in breast cancer tissue. This approach enhances spatial proteomics by complementing untargeted methods, offering deeper disease insights.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) and immunohistochemistry (IHC) are powerful techniques for analyzing biomolecules in tissues.
- Combining MALDI-MSI and IHC offers a novel approach for highly multiplexed, targeted imaging of proteins.
- Existing methods may have limitations in simultaneously analyzing multiple targets with high spatial resolution.
Purpose of the Study:
- To explore the utility and complementarity of targeted MALDI-IHC with untargeted on-tissue bottom-up spatial proteomics.
- To investigate the impact of the MALDI-2 effect on MALDI-IHC performance.
- To demonstrate the application of this combined approach in breast cancer tissue analysis.
Main Methods:
- Multiplexed MALDI-IHC was performed on formalin-fixed paraffin-embedded (FFPE) human breast cancer tissue using a panel of six photocleavable mass-tagged (PC-MT) antibodies.
- K-means clustering of MALDI-IHC images guided laser-capture microdissection (LMD) for subsequent untargeted LC-MS-based bottom-up proteomics.
- MALDI-2 post-ionization was employed to assess its effect on PC-MT intensity.
Main Results:
- MALDI-IHC successfully achieved multiplexed imaging of targeted proteins in breast cancer tissue.
- Untargeted proteomics identified numerous peptides, with some proteins (vimentin, keratins, actin) aligning with the antibody panel.
- MALDI-2 post-ionization enhanced the intensity of PC-MTs, indicating potential for new mass-tag development.
Conclusions:
- The combination of multiplexed MALDI-IHC and image-guided proteomics provides complementary information for disease investigation.
- MALDI-IHC facilitates straightforward identification of proteins, even those missed by untargeted approaches.
- This integrated workflow holds significant potential for advancing spatial biology research without requiring specialized equipment.
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