Integrated mass spectrometry imaging and omics workflows on the same tissue section using grid-aided,...

Area of Science:

• Biochemistry
• Proteomics
• Metabolomics

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) has numerous applications but is limited in identifying multiple compound classes on a single tissue section.
• Existing methods often require multiple sections for comprehensive analysis, increasing tissue consumption and potentially introducing variability.

Purpose of the Study:

• To develop and validate a combined workflow for MALDI MS imaging, shotgun proteomics, and metabolomics using a single tissue section.
• To overcome the limitations of identifying multiple compound classes simultaneously in MALDI MSI.

Main Methods:

• A grid-aided, parafilm-assisted microdissection technique was employed, using an acid dye grid for guidance.
• The modified Folch method was used to separate metabolites from proteins in dissected tissue pieces.
• Proteins were subjected to controlled digestion to enhance identification yields.

Main Results:

• The proof-of-concept experiment on rat brain successfully identified 162 and 140 metabolite assignments and 890, 1303, and 1059 unique proteins from three regions of interest.
• Integrated analysis revealed biological pathways associated with each region, some of which were missed when analyzing proteins and metabolites separately.

Conclusions:

• This combined MALDI MS imaging and multi-omics approach significantly expands the information obtainable from a single tissue section.
• This represents the first report integrating both imaging and multi-omics analyses within a single workflow on the same tissue section.