Thursday Seminar: Team Larmonier/Saleh

Presentation entitled: “Mass spectrometry imaging to decipher metabolism in complex microenvironment” Resume: “Matrix-assisted Laser Desorption Ionization Mass Spectrometry Imaging (MALDI-MSI) has established itself as one of the most attractive ex-vivo techniques for the spatial characterization of molecules. MALDI-MSI excels in chemical specificity without prior molecular tagging and has become a powerful tool for molecular histology. It has been applied to numerous fields of study, from pharmacokinetics, to tumor detection and even sub-cellular metabolomics. With the increase of its spatial resolution at cellular level, allow by last MALDI sources, we can now consider studying cell interaction in complex microenvironment, however MSI did not allow yet to identify the type of cell present in the tissue. To overcome this limitation, we first developed on mouse spleen as model organ, a multimodal approach, coupling MSI with immunofluorescence on same tissue section. Immunofluorescence is used as ground truth to guide datasets analysis. Secondly, we implemented computational analysis to help to decipher valuable information for the combine dataset. This approach allowed us to identify specific lipid biomarkers from different immune cell types, but also to reveal molecular distribution highlighting unexpected cell population. Now, we are using this multimodal approach on complex pathologic microenvironment. Such as, breast cancer tumors to study, intra tumor heterogeneity and interaction between cancer and healthy cells from tumor microenvironment. This multimodal strategy allows to correlate precisely cellular with molecular information for a deeper insight of complex microenvironment organizations”.