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Richard M Caprioli - One of the best experts on this subject based on the ideXlab platform.
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combining salt doping and matrix sublimation for high spatial resolution MALDI Imaging mass spectrometry of neutral lipids
Analytical Chemistry, 2019Co-Authors: Martin Dufresne, Nathan Heath Patterson, Jeremy L Norris, Richard M CaprioliAbstract:The combination of sodium salt doping of a tissue section along with the sublimation of the matrix 2,5-dihydrobenzoic acid (DHB) was found to be an effective coating for the simultaneous detection of neutral lipids and phospholipids using matrix-assisted laser desorption/ionization (MALDI) Imaging mass spectrometry in positive ionization mode. Lithium, sodium, and potassium acetate were initially screened for their ability to cationize difficult to analyze neutral lipids such as cholesterol esters, cerebrosides, and triglycerides directly from a tissue section. The combination of sodium salt and DHB sublimation was found to be an effective cation/matrix combination for detection of neutral lipids. Further experimental optimizations revealed that sodium carbonate or sodium phosphate followed by DHB sublimation increases the signal intensity of the neutral lipids studied depending on the specific lipid family and tissue type by 10-fold to 140-fold compared with that of previously published methods. Application of sodium carbonate tissue doping and DHB sublimation resulted in crystal sizes ≤2 μm. We were thus able to image a mouse brain cerebellum at a high spatial resolution and detected 37 cerebrosides in a single run using a MALDI-TOF instrument. The combination of sodium doping and DHB sublimation offer a targeted and sensitive approach for the detection of neutral lipids that do not typically ionize well under normal MALDI conditions.
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protein identification strategies in MALDI Imaging mass spectrometry a brief review
Current Opinion in Chemical Biology, 2019Co-Authors: Daniel J Ryan, Jeffrey M Spraggins, Richard M CaprioliAbstract:Matrix assisted laser desorption/ionization (MALDI) Imaging mass spectrometry (IMS) is a powerful technology used to investigate the spatial distributions of thousands of molecules throughout a tissue section from a single experiment. As proteins represent an important group of functional molecules in tissue and cells, the Imaging of proteins has been an important point of focus in the development of IMS technologies and methods. Protein identification is crucial for the biological contextualization of molecular Imaging data. However, gas-phase fragmentation efficiency of MALDI generated proteins presents significant challenges, making protein identification directly from tissue difficult. This review highlights methods and technologies specifically related to protein identification that have been developed to overcome these challenges in MALDI IMS experiments.
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advanced registration and analysis of MALDI Imaging mass spectrometry measurements through autofluorescence microscopy
Analytical Chemistry, 2018Co-Authors: Nathan Heath Patterson, Michael Tuck, Raf Van De Plas, Richard M CaprioliAbstract:The correlation of Imaging mass spectrometry (IMS) with histopathology can help relate novel molecular findings obtained through IMS to the well-characterized and validated histopathology knowledge base. The quality of correlation between these two modalities is limited by the quality of the spatial mapping that is obtained by registration of the two image types. In this work, we develop novel workflows for MALDI IMS-to-microscopy data registration and analysis using nondestructive IMS-compatible wide field autofluorescence (AF) microscopy combined with computational image registration. First, a substantially automated procedure for high-accuracy registration between IMS and microscopy data of the same section is described that explicitly links the MALDI laser ablation pattern imaged by microscopy to its corresponding IMS pixel. Subsequent examination of the registered data allows for high-confidence colocalization of image features between the two modalities, down to single-cell scales within tissue. Building on this IMS-microscopy spatial mapping, we furthermore demonstrate the automated spatial correlation between IMS measurements from serial sections. This AF-registration-driven inter-section analysis, using a combination of nonlinear AF-to-AF and IMS-to-AF image registrations, can be applied to tissue sections that are prepared and imaged with different sample preparations (e.g., lipids vs proteins) and/or that are measured using different spatial resolutions. Importantly, all registrations, whether within a single section or across serial sections, are entirely independent of the IMS intensity signal content and thus unbiased by it.
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absolute quantitative MALDI Imaging mass spectrometry a case of rifampicin in liver tissues
Analytical Chemistry, 2016Co-Authors: Chad W Chumbley, Michelle L. Reyzer, Clifton E. Barry, Laura E Via, Jamie L Allen, Gwendolyn A Marriner, Richard M CaprioliAbstract:Matrix-assisted laser desorption/ionization (MALDI) Imaging mass spectrometry (IMS) elucidates molecular distributions in thin tissue sections. Absolute pixel-to-pixel quantitation has remained a challenge, primarily lacking validation of the appropriate analytical methods. In the present work, isotopically labeled internal standards are applied to tissue sections to maximize quantitative reproducibility and yield accurate quantitative results. We have developed a tissue model for rifampicin (RIF), an antibiotic used to treat tuberculosis, and have tested different methods of applying an isotopically labeled internal standard for MALDI IMS analysis. The application of the standard and subsequently the matrix onto tissue sections resulted in quantitation that was not statistically significantly different from results obtained using HPLC-MS/MS of tissue extracts. Quantitative IMS experiments were performed on liver tissue from an animal dosed in vivo. Each microspot in the quantitative images measures the local concentration of RIF in the thin tissue section. Lower concentrations were detected from the blood vessels and around the portal tracts. The quantitative values obtained from these measurements were comparable (>90% similarity) to HPLC-MS/MS results obtained from extracts of the same tissue.
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absolute quantitative MALDI Imaging mass spectrometry a case of rifampicin in liver tissues
Analytical Chemistry, 2016Co-Authors: Chad W Chumbley, Michelle L. Reyzer, Clifton E. Barry, Laura E Via, Jamie L Allen, Gwendolyn A Marriner, Richard M CaprioliAbstract:Matrix-assisted laser desorption/ionization (MALDI) Imaging mass spectrometry (IMS) elucidates molecular distributions in thin tissue sections. Absolute pixel-to-pixel quantitation has remained a challenge, primarily lacking validation of the appropriate analytical methods. In the present work, isotopically labeled internal standards are applied to tissue sections to maximize quantitative reproducibility and yield accurate quantitative results. We have developed a tissue model for rifampicin (RIF), an antibiotic used to treat tuberculosis, and have tested different methods of applying an isotopically labeled internal standard for MALDI IMS analysis. The application of the standard and subsequently the matrix onto tissue sections resulted in quantitation that was not statistically significantly different from results obtained using HPLC-MS/MS of tissue extracts. Quantitative IMS experiments were performed on liver tissue from an animal dosed in vivo. Each microspot in the quantitative images measures the l...
Isabelle Fournier - One of the best experts on this subject based on the ideXlab platform.
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MALDI Imaging and profiling ms of higher mass proteins from tissue
Journal of the American Society for Mass Spectrometry, 2010Co-Authors: Alexandra Van Remoortere, Michel Salzet, Isabelle Fournier, Julien Franck, Maxence Wisztorski, Rene J M Van Zeijl, Nico Van Den Oever, Remi Longuespee, Andre M Deelder, Liam A. McdonnellAbstract:MALDI Imaging and profiling mass spectrometry of proteins typically leads to the detection of a large number of peptides and small proteins but is much less successful for larger proteins: most ion signals correspond to proteins of m/z < 25,000. This is a severe limitation as many proteins, including cytokines, growth factors, enzymes, and receptors have molecular weights exceeding 25 kDa. The detector technology typically used for protein Imaging, a microchannel plate, is not well suited to the detection of high m/z ions and is prone to detector saturation when analyzing complex mixtures. Here we report increased sensitivity for higher mass proteins by using the CovalX high mass HM1 detector (Zurich, Switzerland), which has been specifically designed for the detection of high mass ions and which is much less prone to detector saturation. The results demonstrate that a range of different sample preparation strategies enable higher mass proteins to be analyzed if the detector technology maintains high detection efficiency throughout the mass range. The detector enables proteins up to 70 kDa to be imaged, and proteins up to 110 kDa to be detected, directly from tissue, and indicates new directions by which the mass range amenable to MALDI Imaging MS and MALDI profiling MS may be extended.
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MALDI Imaging mass spectrometry state of the art technology in clinical proteomics
Molecular & Cellular Proteomics, 2009Co-Authors: Julien Franck, Denis Vinatier, Karim Arafah, Mohamed Elayed, David Bonnel, Daniele Vergara, Amelie Jacquet, Maxence Wisztorski, R Day, Isabelle FournierAbstract:A decade after its inception, MALDI Imaging mass spectrometry has become a unique technique in the proteomics arsenal for biomarker hunting in a variety of diseases. At this stage of development, it is important to ask whether we can consider this technique to be sufficiently developed for routine use in a clinical setting or an indispensable technology used in translational research. In this report, we consider the contributions of MALDI Imaging mass spectrometry and profiling technologies to clinical studies. In addition, we outline new directions that are required to align these technologies with the objectives of clinical proteomics, including: 1) diagnosis based on profile signatures that complement histopathology, 2) early detection of disease, 3) selection of therapeutic combinations based on the individual patient's entire disease-specific protein network, 4) real time assessment of therapeutic efficacy and toxicity, 5) rational redirection of therapy based on changes in the diseased protein network that are associated with drug resistance, and 6) combinatorial therapy in which the signaling pathway itself is viewed as the target rather than any single "node" in the pathway.
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MALDI Imaging of formalin fixed paraffin embedded tissues application to model animals of parkinson disease for biomarker hunting
Journal of Proteome Research, 2008Co-Authors: Jonathan Stauber, Isabelle Fournier, Julien Franck, David Bonnel, Maxence Wisztorski, R Day, R Lemaire, Dominique Croix, Michel SalzetAbstract:After 10 years of important technical developments, MALDI Imaging Mass Spectrometry appears to be a sufficiently mature technology to be introduced in laboratories as a practical approach to exploring tissue properties at the molecular level, particularly in the comparison of normal vs. pathological states to study neurological diseases such as Parkinson’s. In this report, we will present the technology and the development to enable the use of formalin fixed and paraffin embedded tissue (FFPE) tissue in order to examine banked hospital clinical samples.
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direct analysis and MALDI Imaging of formalin fixed paraffin embedded tissue sections
Journal of Proteome Research, 2007Co-Authors: Remi Lemaire, Michel Salzet, Annie Desmons, J C Tabet, Isabelle FournierAbstract:Formalin fixation, generally followed by paraffin embedding, is the standard and well-established processing method employed by pathologist. This treatment conserves and stabilizes biopsy samples for years. Analysis of FFPE tissues from biopsy libraries has been, so far, a challenge for proteomics biomarker studies. Herein, we present two methods for the direct analysis of formalin-fixed, paraffinembedded (FFPE) tissues by MALDI-MS. The first is based on the use of a reactive matrix, 2,4-dinitrophenylhydrazine, useful for FFPE tissues stored less than 1 year. The second approach is applicable for all FFPE tissues regardless of conservation time. The strategy is based on in situ enzymatic digestion of the tissue section after paraffin removal. In situ digestion can be performed on a specific area of the tissue as well as on a very small area (microdigestion). Combining automated microdigestion of a predefined tissue array with either in situ extraction prior to classical nanoLC/MS-MS analysis or automated microspotting of MALDI matrix according to the same array allows the identification of both proteins by nanoLC-nanoESI and MALDI Imaging. When adjacent tissue sections are used, it is, thus, possible to correlate protein identification and molecular Imaging. These combined approaches, along with FFPE tissue analysis provide access to massive amounts of archived samples in the clinical pathology setting.
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Solid ionic matrices for direct tissue analysis and MALDI Imaging.
Analytical Chemistry, 2006Co-Authors: Remi Lemaire, Jean-claude Tabet, P. Ducoroy, J.b. Hendra, Michel Salzet, Isabelle FournierAbstract:Direct analysis of tissue by MALDI-MS allows the acquisition of its biomolecular profile while maintaining the integrity of the tissue, giving cellular localization, and avoiding tedious extraction and purification steps. However, direct tissue analysis generally leads to some extent to a lowered spectral quality due to variation in thickness, freezing tissue date, and nature of the tissue. We present here new technical developments for the direct tissue analysis of peptides with ionic liquid made of matrix mixtures (alpha-cyano-4-hydroxycinnamic acid (CHCA)/2-amino-4-methyl-5-nitropyridine and alpha-cyano-4-hydroxycinnamic acid/N,N-dimethylaniline (CHCA/DANI)). The properties of these direct tissue analysis matrixes, especially CHCA/aniline when compared to CHCA, 2,5-dihydroxybenzoic acid, and sinapinic acid, are as follows: (1) better spectral quality in terms of resolution, sensitivity, intensity, noise, number of compounds detected, and contaminant tolerance, (2) better crystallization on tissues, i.e., coverage capacity, homogeneity of crystallization, homogeneity of crystal sizes, and time of crystallization, (3) better analysis duration in term of vacuum stability, (4) better resistance to laser irradiation especially for high-frequency lasers, (5) better ionic yield in negative mode, and (6) enough fragmentation yield to use the PSD mode on sections to get structural information. Applied to MALDI Imaging on a MALDI LIFT-TOF with a 50-Hz laser frequency, these ionic matrixes have allowed the realization of a new type of image in both polarities and reflector mode using the same tissue section. These results give a new outlook on peptide tissue profiling by MS, characterization of compounds from tissue slices, and MALDI-MS high-quality Imaging.
Michel Salzet - One of the best experts on this subject based on the ideXlab platform.
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MALDI Imaging and profiling ms of higher mass proteins from tissue
Journal of the American Society for Mass Spectrometry, 2010Co-Authors: Alexandra Van Remoortere, Michel Salzet, Isabelle Fournier, Julien Franck, Maxence Wisztorski, Rene J M Van Zeijl, Nico Van Den Oever, Remi Longuespee, Andre M Deelder, Liam A. McdonnellAbstract:MALDI Imaging and profiling mass spectrometry of proteins typically leads to the detection of a large number of peptides and small proteins but is much less successful for larger proteins: most ion signals correspond to proteins of m/z < 25,000. This is a severe limitation as many proteins, including cytokines, growth factors, enzymes, and receptors have molecular weights exceeding 25 kDa. The detector technology typically used for protein Imaging, a microchannel plate, is not well suited to the detection of high m/z ions and is prone to detector saturation when analyzing complex mixtures. Here we report increased sensitivity for higher mass proteins by using the CovalX high mass HM1 detector (Zurich, Switzerland), which has been specifically designed for the detection of high mass ions and which is much less prone to detector saturation. The results demonstrate that a range of different sample preparation strategies enable higher mass proteins to be analyzed if the detector technology maintains high detection efficiency throughout the mass range. The detector enables proteins up to 70 kDa to be imaged, and proteins up to 110 kDa to be detected, directly from tissue, and indicates new directions by which the mass range amenable to MALDI Imaging MS and MALDI profiling MS may be extended.
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MALDI Imaging of Formalin-Fixed Paraffin-Embedded Tissues: Application to Model Animals of Parkinson Disease for Biomarker Hunting.
Journal of Proteome Research, 2008Co-Authors: J. Stauber, Julien Franck, R Day, R Lemaire, M. Wisztorski, Bonnel David, I. Fournier, Michel SalzetAbstract:A common technique for the long-term storage of tissues in hospitals and clinical laboratories is preservation in formalin-fixed paraffin-embedded (FFPE) blocks. Such tissues stored for more than five years have not been useful for proteomic studies focused on biomarker discovery. Recently, MS-based proteomic analyses of FFPE showed positive results on blocks stored for less than 2 days. However, most samples are stored for more than one year, and thus our objective was to establish a novel strategy using as a model system 6-hydroxydopamine (6-OHDA) treated rat brain tissues stored in FFPE blocks for more than 9 years. We examined MALDI tissue profiling combining the use of automatic spotting of the MALDI matrix with in situ tissue enzymatic digestion. On adjacent sections, the identification of compounds is carried out by tissue digestion followed by nanoLC/MS-MS analysis. The combination of these approaches provides MALDI direct analysis, MALDI/MS Imaging, as well as the localization of a large number of proteins. This method is validated since the analyses confirmed that ubiquitin, trans-elongation factor 1, hexokinase, and the Neurofilament M are down-regulated as previously shown in human or Parkinson animal models. In contrast, peroxidoredoxin 6, F1 ATPase, and alpha-enolase are up-regulated. In addition, we uncovered three novel putative biomarkers, the trans-elongation factor 1 (eEF1) and the collapsin response mediator 1 and 2 from protein libraries. Finally, we validate the CRMP-2 protein using immunocytochemistry and MALDI Imaging based on the different ions from trypsic digestion of the protein. The access to archived FFPE tissue using MALDI profiling and Imaging opens a whole new area in clinical studies and biomarker discovery from hospital biopsy libraries
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MALDI Imaging of formalin fixed paraffin embedded tissues application to model animals of parkinson disease for biomarker hunting
Journal of Proteome Research, 2008Co-Authors: Jonathan Stauber, Isabelle Fournier, Julien Franck, David Bonnel, Maxence Wisztorski, R Day, R Lemaire, Dominique Croix, Michel SalzetAbstract:After 10 years of important technical developments, MALDI Imaging Mass Spectrometry appears to be a sufficiently mature technology to be introduced in laboratories as a practical approach to exploring tissue properties at the molecular level, particularly in the comparison of normal vs. pathological states to study neurological diseases such as Parkinson’s. In this report, we will present the technology and the development to enable the use of formalin fixed and paraffin embedded tissue (FFPE) tissue in order to examine banked hospital clinical samples.
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direct analysis and MALDI Imaging of formalin fixed paraffin embedded tissue sections
Journal of Proteome Research, 2007Co-Authors: Remi Lemaire, Michel Salzet, Annie Desmons, J C Tabet, Isabelle FournierAbstract:Formalin fixation, generally followed by paraffin embedding, is the standard and well-established processing method employed by pathologist. This treatment conserves and stabilizes biopsy samples for years. Analysis of FFPE tissues from biopsy libraries has been, so far, a challenge for proteomics biomarker studies. Herein, we present two methods for the direct analysis of formalin-fixed, paraffinembedded (FFPE) tissues by MALDI-MS. The first is based on the use of a reactive matrix, 2,4-dinitrophenylhydrazine, useful for FFPE tissues stored less than 1 year. The second approach is applicable for all FFPE tissues regardless of conservation time. The strategy is based on in situ enzymatic digestion of the tissue section after paraffin removal. In situ digestion can be performed on a specific area of the tissue as well as on a very small area (microdigestion). Combining automated microdigestion of a predefined tissue array with either in situ extraction prior to classical nanoLC/MS-MS analysis or automated microspotting of MALDI matrix according to the same array allows the identification of both proteins by nanoLC-nanoESI and MALDI Imaging. When adjacent tissue sections are used, it is, thus, possible to correlate protein identification and molecular Imaging. These combined approaches, along with FFPE tissue analysis provide access to massive amounts of archived samples in the clinical pathology setting.
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Solid ionic matrices for direct tissue analysis and MALDI Imaging.
Analytical Chemistry, 2006Co-Authors: Remi Lemaire, Jean-claude Tabet, P. Ducoroy, J.b. Hendra, Michel Salzet, Isabelle FournierAbstract:Direct analysis of tissue by MALDI-MS allows the acquisition of its biomolecular profile while maintaining the integrity of the tissue, giving cellular localization, and avoiding tedious extraction and purification steps. However, direct tissue analysis generally leads to some extent to a lowered spectral quality due to variation in thickness, freezing tissue date, and nature of the tissue. We present here new technical developments for the direct tissue analysis of peptides with ionic liquid made of matrix mixtures (alpha-cyano-4-hydroxycinnamic acid (CHCA)/2-amino-4-methyl-5-nitropyridine and alpha-cyano-4-hydroxycinnamic acid/N,N-dimethylaniline (CHCA/DANI)). The properties of these direct tissue analysis matrixes, especially CHCA/aniline when compared to CHCA, 2,5-dihydroxybenzoic acid, and sinapinic acid, are as follows: (1) better spectral quality in terms of resolution, sensitivity, intensity, noise, number of compounds detected, and contaminant tolerance, (2) better crystallization on tissues, i.e., coverage capacity, homogeneity of crystallization, homogeneity of crystal sizes, and time of crystallization, (3) better analysis duration in term of vacuum stability, (4) better resistance to laser irradiation especially for high-frequency lasers, (5) better ionic yield in negative mode, and (6) enough fragmentation yield to use the PSD mode on sections to get structural information. Applied to MALDI Imaging on a MALDI LIFT-TOF with a 50-Hz laser frequency, these ionic matrixes have allowed the realization of a new type of image in both polarities and reflector mode using the same tissue section. These results give a new outlook on peptide tissue profiling by MS, characterization of compounds from tissue slices, and MALDI-MS high-quality Imaging.
Rita Casadonte - One of the best experts on this subject based on the ideXlab platform.
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a new classification method for MALDI Imaging mass spectrometry data acquired on formalin fixed paraffin embedded tissue samples
Biochimica et Biophysica Acta, 2017Co-Authors: Tobias Boskamp, Janina Oetjen, Rita Casadonte, Dennis Trede, Peter Maass, Arne Warth, Delf Lachmund, Yovany Cordero Hernandez, Jorg Kriegsmann, Hendrik DienemannAbstract:Matrix-assisted laser desorption/ionization Imaging mass spectrometry (MALDI IMS) shows a high potential for applications in histopathological diagnosis, and in particular for supporting tumor typing and subtyping. The development of such applications requires the extraction of spectral fingerprints that are relevant for the given tissue and the identification of biomarkers associated with these spectral patterns. We propose a novel data analysis method based on the extraction of characteristic spectral patterns (CSPs) that allow automated generation of classification models for spectral data. Formalin-fixed paraffin embedded (FFPE) tissue samples from N=445 patients assembled on 12 tissue microarrays were analyzed. The method was applied to discriminate primary lung and pancreatic cancer, as well as adenocarcinoma and squamous cell carcinoma of the lung. A classification accuracy of 100% and 82.8%, resp., could be achieved on core level, assessed by cross-validation. The method outperformed the more conventional classification method based on the extraction of individual m/z values in the first application, while achieving a comparable accuracy in the second. LC-MS/MS peptide identification demonstrated that the spectral features present in selected CSPs correspond to peptides relevant for the respective classification. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.
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proteomic analysis of formalin fixed paraffin embedded tissue by MALDI Imaging mass spectrometry
Nature Protocols, 2011Co-Authors: Rita Casadonte, Richard M CaprioliAbstract:Proteomic analysis of formalin-fixed paraffin-embedded tissue by MALDI Imaging mass spectrometry
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Proteomic analysis of formalin-fixed paraffin-embedded tissue by MALDI Imaging mass spectrometry
Nature Protocols, 2011Co-Authors: Rita Casadonte, Richard M CaprioliAbstract:Archived formalin-fixed paraffin-embedded (FFPE) tissue collections represent a valuable informational resource for proteomic studies. Multiple FFPE core biopsies can be assembled in a single block to form tissue microarrays (TMAs). We describe a protocol for analyzing protein in FFPE-TMAs using matrix-assisted laser desorption/ionization (MALDI) Imaging mass spectrometry (IMS). The workflow incorporates an antigen retrieval step following deparaffinization, in situ trypsin digestion, matrix application and then mass spectrometry signal acquisition. The direct analysis of FFPE-TMA tissue using IMS allows direct analysis of multiple tissue samples in a single experiment without extraction and purification of proteins. The advantages of high speed and throughput, easy sample handling and excellent reproducibility make this technology a favorable approach for the proteomic analysis of clinical research cohorts with large sample numbers. For example, TMA analysis of 300 FFPE cores would typically require 6 h of total time through data acquisition, not including data analysis.
Pierre Chaurand - One of the best experts on this subject based on the ideXlab platform.
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sublimation of new matrix candidates for high spatial resolution Imaging mass spectrometry of lipids enhanced information in both positive and negative polarities after 1 5 diaminonapthalene deposition
Analytical Chemistry, 2012Co-Authors: Aurelien Thomas, Jade Laveaux Charbonneau, Erik Fournaise, Pierre ChaurandAbstract:Matrix sublimation has demonstrated to be a powerful approach for high-resolution matrix-assisted laser desorption ionization (MALDI) Imaging of lipids, providing very homogeneous solvent-free deposition. This work presents a comprehensive study aiming to evaluate current and novel matrix candidates for high spatial resolution MALDI Imaging mass spectrometry of lipids from tissue section after deposition by sublimation. For this purpose, 12 matrices including 2,5-dihydroxybenzoic acid (DHB), sinapinic acid (SA), α-cyano-4-hydroxycinnamic acid (CHCA), 2,6-dihydroxyacetphenone (DHA), 2′,4′,6′-trihydroxyacetophenone (THAP), 3-hydroxypicolinic acid (3-HPA), 1,8-bis(dimethylamino)naphthalene (DMAN), 1,8,9-anthracentriol (DIT), 1,5-diaminonapthalene (DAN), p-nitroaniline (NIT), 9-aminoacridine (9-AA), and 2-mercaptobenzothiazole (MBT) were investigated for lipid detection efficiency in both positive and negative ionization modes, matrix interferences, and stability under vacuum. For the most relevant matrices, ...
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From Whole-body Sections Down to Cellular Level, Multiscale Imaging of Phospholipids by MALDI Mass Spectrometry
Molecular & Cellular Proteomics, 2011Co-Authors: Pierre Chaurand, D. Shannon. Cornett, Peggi M. Angel, Richard M CaprioliAbstract:Significant progress in instrumentation and sample preparation approaches have recently expanded the potential of MALDI Imaging mass spectrometry to the analysis of phospholipids and other endogenous metabolites naturally occurring in tissue specimens. Here we explore some of the requirements necessary for the successful analysis and Imaging of phospholipids from thin tissue sections of various dimensions by MALDI time-of-flight mass spectrometry. We address methodology issues relative to the Imaging of whole-body sections such as those cut from model laboratory animals, sections of intermediate dimensions typically prepared from individual organs, as well as the requirements for Imaging areas of interests from these sections at a cellular scale spatial resolution. We also review existing limitations of MALDI Imaging MS technology relative to compound identification. Finally, we conclude with a perspective on important issues relative to data exploitation and management that need to be solved to maximize biological understanding of the tissue specimen investigated.
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high throughput proteomic analysis of formalin fixed paraffin embedded tissue microarrays using MALDI Imaging mass spectrometry
Proteomics, 2008Co-Authors: Reid M Groseclose, Pierre Chaurand, Richard M Caprioli, Pierre P MassionAbstract:A novel method for high-throughput proteomic analysis of formalin-fixed paraffin-embedded (FFPE) tissue microarrays (TMA) is described using on-tissue tryptic digestion followed by MALDI Imaging MS. A TMA section containing 112 needle core biopsies from lung-tumor patients was analyzed using MS and the data were correlated to a serial hematoxylin and eosin (H&E)-stained section having various histological regions marked, including cancer, non-cancer, and normal ones. By correlating each mass spectrum to a defined histological region, statistical classification models were generated that can sufficiently distinguish biopsies from adenocarcinoma from squamous cell carcinoma biopsies. These classification models were built using a training set of biopsies in the TMA and were then validated on the remaining biopsies. Peptide markers of interest were identified directly from the TMA section using MALDI MS/MS sequence analysis. The ability to detect and characterize tumor marker proteins for a large cohort of FFPE samples in a high-throughput approach will be of significant benefit not only to investigators studying tumor biology, but also to clinicians for diagnostic and prognostic purposes.
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enhancement of protein sensitivity for MALDI Imaging mass spectrometry after chemical treatment of tissue sections
Journal of the American Society for Mass Spectrometry, 2008Co-Authors: Erin H Seeley, Pierre Chaurand, Stacey R Oppenheimer, Deming Mi, Richard M CaprioliAbstract:MALDI Imaging mass spectrometry (IMS) has become a valuable tool for the investigation of the content and distribution of molecular species in tissue specimens. Numerous methodological improvements have been made to optimize tissue section preparation and matrix deposition protocols, as well as MS data acquisition and processing. In particular for proteomic analyses, washing the tissue sections before matrix deposition has proven useful to improve spectral qualities by increasing ion yields and the number of signals observed. We systematically explore here the effects of several solvent combinations for washing tissue sections. To minimize experimental variability, all of the measurements were performed on serial sections cut from a single mouse liver tissue block. Several other key steps of the process such as matrix deposition and MS data acquisition and processing have also been automated or standardized. To assess efficacy, after each washing procedure the total ion current and number of peaks were counted from the resulting protein profiles. These results were correlated to on-tissue measurements obtained for lipids. Using similar approaches, several selected washing procedures were also tested for their ability to extend the lifetime as well as revive previously cut tissue sections. The effects of these washes on automated matrix deposition and crystallization behavior as well as their ability to preserve tissue histology were also studied. Finally, in a full-scale IMS study, these washing procedures were tested on a human renal cell carcinoma biopsy.
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MALDI Imaging mass spectrometry: molecular snapshots of biochemical systems
Nature Methods, 2007Co-Authors: D. Shannon. Cornett, D Cornett, Pierre Chaurand, M. Reyzer, Richard M CaprioliAbstract:Matrix-assisted laser desorption/ionization (MALDI) Imaging mass spectrometry (IMS) is emerging as a powerful tool for investigating the distribution of molecules within biological systems through the direct analysis of thin tissue sections. Unique among Imaging methods, MALDI-IMS can determine the distribution of hundreds of unknown compounds in a single measurement. We discuss the current state of the art of MALDI-IMS along with some recent applications and technological developments that illustrate not only its current capabilities but also the future potential of the technique to provide a better understanding of the underlying molecular mechanisms of biological processes.