Spatial Molecular Imaging of the Glycome Using Mass Spectrometry

The spatial organization of the glycome within tissues is key to the molecular basis for physiological function. The diverse and dynamic glycome is critical for fundamental cellular processes, including metabolism, signaling, and adhesion. Innovations in spatial biology have ushered in new avenues for spatial molecular imaging of diverse glycome classes. Here, we describe an optimized protocol for spatial biomolecular imaging of the glycome in fresh-frozen mouse liver. The workflow comprises (1) rapid harvesting and freezing, (2) cryostat sectioning at optimal thickness and position, (3) tissue preparation and on-tissue enzyme digestion using carbohydrate-active enzymes, (4) matrix application and data acquisition by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), and (5) data processing and visualization to place the findings in biological context. Use of this approach allows acquisition of detailed spatial maps of N-linked glycans and glycogen, revealing key physiological and cellular features. These data allow the definition of key spatial glycomic heterogeneity associated with liver function and dysfunction. This workflow enables highly reproducible and sensitive spatial glycomics of the mouse liver. Additionally, it is readily adaptable to other tissues or species, facilitating novel spatial insights into glycome biology in health and disease.