title: Tissue fixed with formalin and processed without paraffin embedding is suitable for imaging of both peptides and lipids by MALDI-IMS.
abstract: Type and quality of sample preparation have significant impact on imaging mass spectrometry results. Though imaging of fresh-frozen tissues is considered to give the best results, they are incompatible with clinical practice, since routine diagnostics is most frequently performed using formalin-fixed tissues, and formalin-fixed paraffin-embedded material is a gold standard in histopathology. We aimed to assess utility of formalin-fixed tissue specimen processed without paraffin embedding (i.e., deep-frozen and cryo-sectioned) for MALDI imaging of both peptides and lipids. Peptide and lipid imaging was performed in fresh-frozen, FFPE and formalin-fixed/frozen samples of a mouse kidney, then composition of the resulting spectra was compared. We demonstrated similarity of spectra registered during peptide imaging in FFPE and formalin-fixed/frozen tissues, and similarity of spectra registered during lipid imaging in fresh-frozen and formalin-fixed/frozen material. Furthermore, molecular images of formalin-fixed/frozen tissue resembled the features of both fresh-frozen and FFPE tissue in the case of peptide imaging, and the features of fresh-frozen tissue in the case of lipid imaging. We conclude that tissue preserved by formalin fixation and processed without paraffin embedding can be considered as an alternative to both fresh-frozen and FFPE material.
authors.affiliation: Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Gliwice Branch, Gliwice, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Pietrowska
authors.affiliation: Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Gliwice Branch, Gliwice, Poland.|Department of Analytical Chemistry, Faculty of Chemistry, Jagiellonian University, Kraków, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Gawin
authors.affiliation: Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, Gliwice, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Polańska
authors.affiliation: Center for Translational Research and Molecular Biology of Cancer, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology Gliwice Branch, Gliwice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Widłak
mesh_terms: D000818:Animals; D005557:Formaldehyde / Q000737:chemistry; D006801:Humans; D008055:Lipids / Q000235:genetics / Q000302:isolation & purification*; D051379:Mice; D016612:Paraffin Embedding; D010455:Peptides / Q000235:genetics / Q000302:isolation & purification*; D013048:Specimen Handling; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D016707:Tissue Fixation / Q000379:methods*
chemical_list: D008055:Lipids; D010455:Peptides; D005557:Formaldehyde
keywords: Clinical material; Imaging mass spectrometry; Mouse kidney; Sample preparation; Technology; Tissue fixation