What is MSI?
Mass Spectrometry Imaging (MSI) stands at the forefront of molecular histology, combining the precision of mass spectrometry with the spatial clarity of histology. This technique enables detailed mapping of distributions and concentrations of various molecules across a range of samples, from tissues to environmental samples. With the ability to detect lipids, metabolites, peptides, proteins, glycans, drugs, and toxins it is furthering research in areas such as human health, veterinary medicine, toxicology, agriculture, and environmental science.
Unlocking the Power of Spatial Analysis
MSI not only offers high sensitivity and specificity but also preserves the spatial context of samples. Unlike traditional methods that homogenize tissue and lose critical spatial details, MSI captures hundreds of molecular features in a single experiment while maintaining tissue architecture. This enables researchers to detect unique molecular signatures in specific regions, such as the renal cortex, that might be obscured in bulk analyses.
Furthermore, MSI can be synergistically combined with other imaging techniques, such as immunohistochemistry or histology stains, to enhance the depth of analysis and corroborate findings.
Ion image of host lipids (green, yellow and blue) and a bacterial lipid (red) in hamster kidneys. A. Negative control. B. Infected tissue. Spatial resolution 50 µm. Image credit: UVic Genome BC Proteomics Center and Biology of Spirochetes Unit (Institut Pasteur, Paris, France).
MSI Technologies at TMIC
TMIC’s Goodlett Node at the University of Victoria, utilizes the advanced tims-TOF flex MALDI-2 imaging system for its MS-Imaging projects. This instrument combines TIMS (trapped ion mobility spectrometry ) and MALDI-2 laser technology to deliver high sensitivity and spatial resolution (20-100 µm). Coupled with an LC system for follow-up LC-MS/MS analysis, our imaging capabilities offer a comprehensive approach to molecular research.
Overcoming Challenges
A common challenge with standard MSI workflows is the identification of molecular features based solely on mass-to-charge ratios. To enhance accuracy, we incorporate TIMS into our imaging process. TIMS provides an additional measurement—collision cross-section (CCS)—which helps differentiate molecules based on their gas-phase mobility. This enhancement allows for improved identification and separation of isomers and isobars in complex mixtures. For comprehensive feature annotation in untargeted studies, we recommend combining MSI with traditional LC-MS/MS techniques, available through our fee-for-service offerings.
MSI vs. Other Techniques: What Sets It Apart?
While techniques such as NMR and LC-MS are valuable for detailed molecular analysis, MSI is particularly suited for studies where spatial distribution and localization of molecules are crucial. MSI can identify specific regions of interest within tissues, which can then be further analyzed using traditional LC-MS/MS for enhanced sensitivity and quantification.
Exploring Applications of MSI
MSI is instrumental in a variety of research areas, including:
- Metabolomics in Tumor Microenvironments: Investigating the interaction between tumor cells and immune cell infiltration.
- Bacterial Lipid Signatures: Characterizing lipid profiles of bacteria in vivo.
- Host Tissue Impact: Assessing the effects of infection on host tissue.
- Environmental Exposure Studies: Analyzing perfluorooctane sulfonate (PFOS) in amphibian tissues to understand its effects on brain development.
Image 1: Ion image of a neutral lipid in a fresh-frozen murine joint. Spatial resolution 50 µm. Image credit: UVic Genome BC Proteomics Center and Lochhead laboratory (Medical College of Wisconsin, Milwaukee, WI, USA).
Image 2: Ion image of a tryptic peptide in a murine heart (FFPE). Spatial resolution 50 µm. Image credit: UVic Genome BC Proteomics Center and Lochhead laboratory (Medical College of Wisconsin, Milwaukee, WI, USA).
Image 3: Ion image of a lipid in the head of a froglet. Spatial resolution 50 µm. Image credit: Dr. Poulsen (University of Copenhagen, Copenhagen, DE), UVic Genome BC Proteomics Center and Helbing laboratory (University of Victoria, Victoria, BC, CA).
Other Services provided by Goodlett Node
- Fatty Acid Metabolism – Medium to Long Chain Fatty Acids and Carnitines
- In Vivo Metabolites of Vitamin Co-Metabolism
- Amino Acid Metabolism/Urea Cycle Metabolism
- Phytohormones Assay
- Sphingolipid Synthesis Metabolism
For more details about services contact: info@metabolomicscentre.ca
