[Clinical applications of MALDI imaging using sliced sections of formalin-fixed paraffin-embedded tissues and longitudinal sliced hairs].

MALDI-imaging MS (IMS) with MSMS analysis is a new powerful tool for the identification of not only disease-related proteins in formalin-fixed paraffin-embedded (FFPE) tissue sections but also protein/peptides/drugs/medicine in fresh-frozen tissues. IMS is used to reveal the mass profiles and spatial distribution of proteins in tissue sections and/or digested peptides derived from deposited protein in pathologic organs and then MSMS analysis identifies the amino acid sequence of the detected proteins in the tissue section. Moreover, on-tissue digestion combined with the MALDI-IM-TOF-IMS approach allows a proteomics "bottom-up" strategy with clinical samples, especially perioperative isolated tissues and FFPE tissues conserved for a long time in a clinical sample bank. The mass barcode-like image (MBI) on a longitudinal sliced hair by IMS is used in the selected reaction monitoring mode for serially chronological monitoring and traceability every few hours after drug and medicine intake. The advances of quantitative MBI for sliced sections of hair allow a new universal standardized assessment of drugs and medicines throughout the drug history.