Direct profiling and MALDI Imaging in clinical proteomic

MALDI direct analysis and MALDI imaging of tissues have shown to be a very powerful tool by localizing molecules in tissue and by avoiding extraction, pre-purification, separation. Nevertheless, this new method requires new developments to increase sensitivity and specificity. We propose here a new concept and evolutions of each step of MALDI Imaging analysis. New matrices called Ionic matrices were synthesized to be especially well adapted for a good crystallization, sensitivity and resolution compared to the classical matrices. Moreover, for tissue kept in hospital libraries, FFPE tissues we developed a new strategy of in situ tissue enzymatic digestion was developed in combination with automatic microspotting MALDI Imaging. In order to add a dimension of specificity to imaging by MS, we have developed specific imaging using designed probes directed against specific targets with mass spectrometry detection. This strategy has been developed for different class of biomolecules with a specific highlight, to mRNA and peptides/proteins. This concept is based of indirect detection of specific targeted molecule using a photocleavable tagged probe. The introduction of the specific imaging give another dimension by targeting specific disease-marker-gene RNA transcripts, following their expression within tissues and then confirming their translation by targeting their specific proteinproducts or metabolites