Toward Omics-Scale Quantitative Mass Spectrometry Imaging of Lipids in Brain Tissue Using a Multiclass Internal Standard Mixture
This paper demonstrates an approach for conducting quantitative mass spectrometry imaging (MSI) of lipids directly from brain tissue sections. This greatly expands the utility of MSI for spatial lipidomics.
Access publication
While MSI is a powerful tool for spatially mapping compounds within biological tissues, it is known that ionization of lipids depends on both individual molecular properties and the presence of other lipids. This can lead to varying ion intensities for a given lipid across tissues, even when it is present at the same concentration. As the use of internal standards (IS) has been used to overcome this issue in the quantitative MSI of drugs, this study investigated quantitative MSI of different lipid classes from mouse brain sections using a lipid IS optimised to reflect 13 major lipid classes.
The IS was sprayed onto tissue sections at a known surface concentration before application of MALDI matrices. MSI was conducted using regular MALDI (negative mode) and laser post-ionization MALDI-2 (positive mode) using two different instruments: an Orbitrap Elite (Thermo Fisher) equipped with a MALDI ion source (Spectroglyph), and a timsTOF flex MALDI-2 (Bruker). This approach allowed detection and imaging of hundreds of unique lipid species. Detected lipids were normalized against their respective IS reference peaks, allowing determination of region-specific lipid concentrations and revealed subtle changes in distribution compared to standard TIC normalisztion. In this study, Aspect Analytics conducted the data analysis workflow, including the normalization, plotting of ion images, and co-registration of MSI data to reference histology images.
Publication Details: Michiel Vandenbosch1, Shadrack M Mutuku2, Maria José Q Mantas3, Nathan H Patterson3, Tucker Hallmark4, Marc Claesen3, Ron M A Heeren1, Nathan G Hatcher5, Nico Verbeeck3, Kim Ekroos6, Shane R Ellis2 Toward Omics-Scale Quantitative Mass Spectrometry Imaging of Lipids in Brain Tissue Using a Multiclass Internal Standard Mixture. Analytical Chemistry. 2023 Dec 26;95(51):18719-18730. doi: 10.1021/acs.analchem.3c02724.
AFFILIATIONS
1. Maastricht MultiModal Molecular Imaging (M4I) Institute, Division of Imaging Mass Spectrometry, Maastricht University, Maastricht 6229ER, Netherlands.
2. Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia.
3. Aspect Analytics NV, Genk 3600, Belgium.
4. Avanti Polar Lipids, Alabama, Alabama 35007, United States.
5. Merck & Co., Inc., 770 Sumneytown Pk, West Point, Pennsylvania 19486, United States.
6. Lipidomics Consulting Ltd., Esbo 02230, Finland.