Heterogeneity between and within cell populations plays a vital role in in our understanding of spatial biology and disease. Heterogeneity manifests in phenotypical differences between cells, including distinct lipidomic and metabolomic profiles. Typical metabolomics analyses take a bulk approach that removes analytes from their spatial context. Mass spectrometry imaging (MSI) is a label-free technique enabling the spatial analysis of metabolites in their native environment. High resolution MSI remains challenging due to the inherently low sample volume and requirement for highly specialized instrumentation. Advancements in matrix-assisted laser desorption/ionization (MALDI) MSI have paved the way for subcellular resolution (≤2 µm) through increasing ion yield and optical focus. Plasma ionization has also been investigated as a complementary post-ionization technique serving to increase ion yield and analyte coverage. Through the use of transmission-mode ambient MALDI with in-line plasma ionization in combination with a cresyl-violet (CV) pre-staining technique, researchers were able to simultaneously analyze 200 lipids and nucleotides at 1 µm resolution, obtaining informative MSI data down to 250 nm resolution¹. This research demonstrates that the future of high-resolution MSI hinges on tailored sample-prep as well as purpose-built instrumentation.

References:

1. Young, R.S.E., Piper, AK., McAlary, L. et al. Subcellular mass spectrometry imaging of lipids and nucleotides using transmission geometry ambient laser desorption and plasma ionisation. Nat Commun 16, 9130 (2025). https://doi.org/10.1038/s41467-025-64604-7