Developments and Latest Applications of Desorption Electrospray Ionization Mass Spectrometry Imaging of Biological Tissues and Cell Cultures

This presentation briefly reviews the capabilities of various MS imaging methods, particularly those of DESI. The body of the talk covers DESI imaging applications such as microorganism cultures, intact plant tissue and diseased animal (and human) tissue. The ability to identify metabolic products under a variety of stimulation conditions is shown using DESI imaging and a simple ion trap mass spectrometer capable of MS/MS. The use of DESI to follow the early stages of embryological development through spatially and temporally resolved lipid profiles is illustrated in some detail using recent examples emphasizing the impact of in vitro culture systems. DESI-MS has been shown to provide comprehensive analytical information on small molecules (especially lipids) from complex microscopic and valuable biological samples. Analysis of organisms/cells end-point metabolism by DESI-MS can be used for bottom-up (DESI-MS data is used to guide proteomics, transcriptomics os genomics analysis) or top-down metabolomics (DESI-MS data is collected to confirm and detail pathways indicated by other omics methods). A third example seeks to distinguish various stages of cancer in dogs and humans. Data shows that powerful, fast and informative small molecule analysis by DESI is provided from complex biological models. This approach is especially interesting if limited amount of sample is available and/or a large number of samples must be analyzed. DESI-MS represents an end-point metabolic analysis and can be therefore integrated to other omics approaches. These capabilities depends heavily on advanced bioinformatics methods which are also discussed.