Sample Preparation for Metabolite Detection in Mass Spectrometry Imaging

Area of Science:

• Analytical Chemistry
• Biochemistry
• Molecular Imaging

Background:

• Metabolites are key indicators of cellular and tissue biological states, making metabolomics crucial for understanding physiology and disease.
• Mass spectrometry imaging (MSI) is vital for analyzing heterogeneous tissues by preserving analyte spatial distribution.
• Small, polar metabolites are prone to diffusion during sample preparation, complicating MSI analysis.

Purpose of the Study:

• To develop and present an optimized sample preparation method for fresh frozen tissue sections.
• To minimize diffusion and delocalization of small polar metabolites during MSI sample preparation.
• To improve the accuracy of spatial metabolomics in heterogeneous tissues.

Main Methods:

• Cryosectioning of fresh frozen tissue.
• Vacuum frozen storage of tissue sections.
• Optimized matrix application for MALDI-MSI.
• Vacuum drying and vacuum packing techniques.
• Adaptability of cryosectioning and vacuum freezing for DESI-MSI.

Main Results:

• The developed protocol effectively limits the diffusion and delocalization of small polar metabolites.
• Preserved spatial integrity of metabolites in fresh frozen tissue sections.
• Demonstrated applicability for both MALDI-MSI and DESI-MSI (with modifications).
• Vacuum drying and packing ensure safe storage and further reduce analyte mobility.

Conclusions:

• The presented method significantly enhances the spatial resolution and reliability of metabolomics in heterogeneous tissues.
• This protocol is crucial for accurate MSI analysis of small polar metabolites, advancing physiological and disease research.
• The method provides a robust approach for sample handling and storage in spatial metabolomics workflows.