| Revision as of 14:48, 28 March 2015 editTpowers89 (talk | contribs)2 editsm Fixed citation← Previous edit | Revision as of 19:23, 30 March 2015 edit undoTmyers14 (talk | contribs)62 edits Sample preparation expansionNext edit → | ||
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| == Sample preparation == | == Sample preparation == | ||
| ] | ] | ||
| Scientists take thin tissue slices mounted on conductive microscope slides and apply a suitable MALDI matrix to the tissue, either manually or automatically. Next, the microscope slide is inserted into a MALDI mass spectrometer. The mass spectrometer records the spatial distribution of molecular species such as peptides, proteins or small molecules. Suitable image processing software can be used to import data from the mass spectrometer to allow visualization and comparison with the optical image of the sample. Recent work has also demonstrated the capacity to create three-dimensional molecular images using MALDI imaging technology and comparison of these image volumes to other imaging modalities such as ] (]).<ref name="pmid18165806">{{cite journal |author=Andersson M, Groseclose MR, Deutch AY, Caprioli RM |title=Imaging Mass Spectrometry of Proteins and Peptides: 3D Volume Reconstruction |journal=Nature Methods |volume=5 |issue=1 |pages=101–108 |year=2008 |pmid=18165806 |doi=10.1038/nmeth1145}}</ref><ref name="pmid18084298">{{cite journal |author=Sinha TK, Khatib-Shahidi S, Yankeelov TE, Mapara K, Ehtesham M, Cornett DS, Dawant BM, Caprioli RM, Gore JC |title=Integrating Spatially Resolved Three-Dimensional MALDI IMS with in vivo Magnetic Resonance Imaging |journal=Nature Methods |volume=5 |issue=1 |pages=57–59 |year=2008 |pmid=18084298 |doi=10.1038/nmeth1147 |pmc=2649801}}</ref> | Sample preparation is a critical step in imaging spectroscopy. Scientists take thin tissue slices mounted on conductive microscope slides and apply a suitable MALDI matrix to the tissue, either manually or automatically. Next, the microscope slide is inserted into a MALDI mass spectrometer. The mass spectrometer records the spatial distribution of molecular species such as peptides, proteins or small molecules. Suitable image processing software can be used to import data from the mass spectrometer to allow visualization and comparison with the optical image of the sample. Recent work has also demonstrated the capacity to create three-dimensional molecular images using MALDI imaging technology and comparison of these image volumes to other imaging modalities such as ] (]).<ref name="pmid18165806">{{cite journal |author=Andersson M, Groseclose MR, Deutch AY, Caprioli RM |title=Imaging Mass Spectrometry of Proteins and Peptides: 3D Volume Reconstruction |journal=Nature Methods |volume=5 |issue=1 |pages=101–108 |year=2008 |pmid=18165806 |doi=10.1038/nmeth1145}}</ref><ref name="pmid18084298">{{cite journal |author=Sinha TK, Khatib-Shahidi S, Yankeelov TE, Mapara K, Ehtesham M, Cornett DS, Dawant BM, Caprioli RM, Gore JC |title=Integrating Spatially Resolved Three-Dimensional MALDI IMS with in vivo Magnetic Resonance Imaging |journal=Nature Methods |volume=5 |issue=1 |pages=57–59 |year=2008 |pmid=18084298 |doi=10.1038/nmeth1147 |pmc=2649801}}</ref> | ||
| === |
=== Tissue preparation === | ||
| The tissue samples must be preserved quickly in order to reduced molecular degradation. The first step is to freeze the sample by wrapping the sample then submerging it in a cryogenic solution.<ref name="caprioli2013">{{cite journal|last1=Norris|first1=Jeremy L.|last2=Caprioli|first2=Richard M.|title=Analysis of Tissue Specimens by Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry in Biological and Clinical Research|journal=Chemical Reviews|date=10 April 2013|volume=113|issue=4|pages=2309–2342|doi=10.1021/cr3004295}}</ref> Once frozen, the samples can be stored below -80°C for up to a year.<ref name=caprioli2013/> | |||
| When ready to be analyzed, the tissue is embedded in a gelatin media which supports the tissue while it is being cut, while reducing contamination that is seen in ] (OCT) techniques.<ref name=caprioli2013/> The mounted tissue section thickness varies depending on the tissue. | |||
| <br /> | |||
| Tissue sections can then be thaw mounted by placing the sample on the surface of a conductive slide that is of the same temperature, and then slowly warmed from below.<ref name=caprioli2013/> The section can also be adhered to the surface of a warm slide by slowly lowering the slide over the cold sample until the sample sticks to the surface.<ref name=caprioli2013/> | |||
| <br /> | |||
| The sample can then be stained in order to easily target areas of interest, and pretreated with washing in order to remove species that suppress molecules of interest.<ref name=caprioli2013/> Washing with varying grades of ethanol removes lipids in tissues that have a high lipid concentration with little delocalization and maintains the integrity of the peptide spatial arrangement within the sample.<ref name=caprioli2013/><ref>{{cite journal|last1=Hanreider|first1=J.|last2=Ljungdahl|first2=A.|last3=Faelth|first3=M.|last4=Mammo|first4=S. E.|last5=Bergquist|first5=J.|last6=Andersson|first6=M.|journal=Mol. Cell. Proteomics|date=2011|volume=10}}</ref> | |||
| ] | ] | ||
| === Matrix application === | |||
| The ] must absorb at the laser wavelength and ionize the analyte. Matrix selection and solvent system relies heavily upon the analyte class desired in imaging. The analyte must be soluble in the solvent in order to mix and recrystallize the matrix. The matrix must have a ] coating in order to increase sensitivity, intensity, and shot-to-shot reproducibility. Minimal solvent is used when applying the matrix in order to avoid delocalization. | |||
| <br /> | |||
| One technique is spraying. The matrix is sprayed, as very small droplets, onto the surface of the sample, allowed to dry, and re-coated until there is enough matrix to analyze the sample.<ref name=caprioli2013/> The size of the crystals depend on the solvent system used. | |||
| <br /> | |||
| ] can also be used to make uniform matrix coatings with very small crystals.<ref name=caprioli2013/><ref name="hankin2007">{{cite journal|last1=Hankin|first1=J. A.|last2=Barkley|first2=R. M.|last3=Murphy|first3=R. C.|journal=J. Am. Soc. Mass Spectrom.|date=2007|volume=18|page=1646}}</ref> The matrix is place in a sublimation chamber with the mounted tissue sample inverted above it.<ref name=caprioli2013/> Heat is applied to the matrix, causing it to sublime and condense onto the surface of the sample.<ref name=caprioli2013/> Controlling the heating time controls the thickness of the matrix on the sample and the size of the crystals formed.<ref name=caprioli2013/><ref name=hankin2007/> | |||
| <br /> | |||
| Automated spotters are also used by regularly spacing droplets throughout the tissue sample.<ref name=caprioli2013/> The image resolution relies on the spacing of the droplets.<ref name=caprioli2013/> | |||
| === Image production === | |||
| Images are constructed by plotting ion intensity versus relative position of the data from the sample.<ref name=caprioli2013/><ref>{{cite journal|last1=Spraggins|first1=Jeffrey M.|last2=Caprioli|first2=Richard M.|title=High-Speed MALDI-TOF Imaging Mass Spectrometry: Rapid Ion Image Acquisition and Considerations for Next Generation Instrumentation|journal=J. Am. Soc. Mass Spectrom.|date=2011|volume=22|page=1022-1031|doi=10.1007/s13361-011-0121-0}}</ref> Spatial resolution highly impacts the molecular information gained from analysis. | |||
| ==Applications== | ==Applications== | ||
| MALDI-IMS involves the visualization of the spatial distribution of proteins, peptides, lipids, drug candidate compounds and their metabolites, biomarkers or other chemicals within thin slices of sample such as animal or plant tissue.<ref name="pmid15677390">{{cite journal |author=Caldwell RL, Caprioli RM |title=Tissue profiling by mass spectrometry: a review of methodology and applications |journal=Mol. Cell Proteomics |volume=4 |issue=4 |pages=394–401 |year=2005 |pmid=15677390 |doi=10.1074/mcp.R500006-MCP200}}</ref><ref name="pmid17185024">{{cite journal |author=Reyzer ML, Caprioli RM |title=MALDI-MS-based imaging of small molecules and proteins in tissues |journal=Current Opinion in Chemical Biology |volume=11 |issue=1 |pages=29–35 |year=2007 |pmid=17185024 |doi=10.1016/j.cbpa.2006.11.035}}</ref><ref name="pmid16796390">{{cite journal |author=Woods AS, Jackson SN |title=Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry |journal=The AAPS journal |volume=8 |issue=2 |pages=E391–5 |year=2006 |pmid=16796390 |doi=10.1208/aapsj080244 |pmc=3231574}}</ref><ref name="doi=10.1016/j.ijms.2006.10.007">{{cite journal |author=Stoeckli M, Staab D, Schweitzer A |title=Compound and metabolite distribution measured by MALDI mass spectrometric imaging in whole-body tissue sections |journal=International Journal of Mass Spectrometry |volume=260 |issue=2-3 |pages=195–202 |year=2006 |doi=10.1016/j.ijms.2006.10.007}}</ref><ref name="PMID 16970320">{{cite journal |author=Khatib-Shahidi S, Andersson M, Herman JL, Gillespie TA, Caprioli RM |title=Direct Molecular Analysis of Whole-body Animal Tissue Sections by Imaging MALDI Mass Spectrometry |journal=Analytical Chemistry |volume=78 |issue=18 |pages=6448–6456 |year=2006 |pmid=16970320 |doi=10.1021/ac060788p}}</ref> It is a promising tool for putative biomarker characterization and drug development. | MALDI-IMS involves the visualization of the spatial distribution of proteins, peptides, lipids, drug candidate compounds and their metabolites, biomarkers or other chemicals within thin slices of sample such as animal or plant tissue.<ref name="pmid15677390">{{cite journal |author=Caldwell RL, Caprioli RM |title=Tissue profiling by mass spectrometry: a review of methodology and applications |journal=Mol. Cell Proteomics |volume=4 |issue=4 |pages=394–401 |year=2005 |pmid=15677390 |doi=10.1074/mcp.R500006-MCP200}}</ref><ref name="pmid17185024">{{cite journal |author=Reyzer ML, Caprioli RM |title=MALDI-MS-based imaging of small molecules and proteins in tissues |journal=Current Opinion in Chemical Biology |volume=11 |issue=1 |pages=29–35 |year=2007 |pmid=17185024 |doi=10.1016/j.cbpa.2006.11.035}}</ref><ref name="pmid16796390">{{cite journal |author=Woods AS, Jackson SN |title=Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry |journal=The AAPS journal |volume=8 |issue=2 |pages=E391–5 |year=2006 |pmid=16796390 |doi=10.1208/aapsj080244 |pmc=3231574}}</ref><ref name="doi=10.1016/j.ijms.2006.10.007">{{cite journal |author=Stoeckli M, Staab D, Schweitzer A |title=Compound and metabolite distribution measured by MALDI mass spectrometric imaging in whole-body tissue sections |journal=International Journal of Mass Spectrometry |volume=260 |issue=2-3 |pages=195–202 |year=2006 |doi=10.1016/j.ijms.2006.10.007}}</ref><ref name="PMID 16970320">{{cite journal |author=Khatib-Shahidi S, Andersson M, Herman JL, Gillespie TA, Caprioli RM |title=Direct Molecular Analysis of Whole-body Animal Tissue Sections by Imaging MALDI Mass Spectrometry |journal=Analytical Chemistry |volume=78 |issue=18 |pages=6448–6456 |year=2006 |pmid=16970320 |doi=10.1021/ac060788p}}</ref> It is a promising tool for putative biomarker characterization and drug development. | ||
Revision as of 19:23, 30 March 2015
MALDI imaging mass spectrometry (MALDI-IMS) is the use of matrix-assisted laser desorption ionization as a mass spectrometry imaging technique in which the sample, often a thin tissue section, is moved in two dimensions while the mass spectrum is recorded. Advantages, like measuring the distribution of a large amount of analytes at one time without destroying the sample, make it a useful method in tissue-based study.
Sample preparation
Sample preparation is a critical step in imaging spectroscopy. Scientists take thin tissue slices mounted on conductive microscope slides and apply a suitable MALDI matrix to the tissue, either manually or automatically. Next, the microscope slide is inserted into a MALDI mass spectrometer. The mass spectrometer records the spatial distribution of molecular species such as peptides, proteins or small molecules. Suitable image processing software can be used to import data from the mass spectrometer to allow visualization and comparison with the optical image of the sample. Recent work has also demonstrated the capacity to create three-dimensional molecular images using MALDI imaging technology and comparison of these image volumes to other imaging modalities such as magnetic resonance imaging (MRI).
Tissue preparation
The tissue samples must be preserved quickly in order to reduced molecular degradation. The first step is to freeze the sample by wrapping the sample then submerging it in a cryogenic solution. Once frozen, the samples can be stored below -80°C for up to a year.
When ready to be analyzed, the tissue is embedded in a gelatin media which supports the tissue while it is being cut, while reducing contamination that is seen in optimal cutting temperature compound (OCT) techniques. The mounted tissue section thickness varies depending on the tissue.
Tissue sections can then be thaw mounted by placing the sample on the surface of a conductive slide that is of the same temperature, and then slowly warmed from below. The section can also be adhered to the surface of a warm slide by slowly lowering the slide over the cold sample until the sample sticks to the surface.
The sample can then be stained in order to easily target areas of interest, and pretreated with washing in order to remove species that suppress molecules of interest. Washing with varying grades of ethanol removes lipids in tissues that have a high lipid concentration with little delocalization and maintains the integrity of the peptide spatial arrangement within the sample.
Matrix application
The matrix must absorb at the laser wavelength and ionize the analyte. Matrix selection and solvent system relies heavily upon the analyte class desired in imaging. The analyte must be soluble in the solvent in order to mix and recrystallize the matrix. The matrix must have a homogeneous coating in order to increase sensitivity, intensity, and shot-to-shot reproducibility. Minimal solvent is used when applying the matrix in order to avoid delocalization.
One technique is spraying. The matrix is sprayed, as very small droplets, onto the surface of the sample, allowed to dry, and re-coated until there is enough matrix to analyze the sample. The size of the crystals depend on the solvent system used.
Sublimation can also be used to make uniform matrix coatings with very small crystals. The matrix is place in a sublimation chamber with the mounted tissue sample inverted above it. Heat is applied to the matrix, causing it to sublime and condense onto the surface of the sample. Controlling the heating time controls the thickness of the matrix on the sample and the size of the crystals formed.
Automated spotters are also used by regularly spacing droplets throughout the tissue sample. The image resolution relies on the spacing of the droplets.
Image production
Images are constructed by plotting ion intensity versus relative position of the data from the sample. Spatial resolution highly impacts the molecular information gained from analysis.
Applications
MALDI-IMS involves the visualization of the spatial distribution of proteins, peptides, lipids, drug candidate compounds and their metabolites, biomarkers or other chemicals within thin slices of sample such as animal or plant tissue. It is a promising tool for putative biomarker characterization and drug development.
See also
References
- Powers, Thomas W.; Neely, Benjamin A.; Shao, Yuan; Tang, Huiyuan; Troyer, Dean A.; Mehta, Anand S.; Haab, Brian B.; Drake, Richard R. (2014). "MALDI Imaging Mass Spectrometry Profiling of N-Glycans in Formalin-Fixed Paraffin Embedded Clinical Tissue Blocks and Tissue Microarrays". PLoS ONE. 9 (9): e106255. doi:10.1371/journal.pone.0106255. ISSN 1932-6203.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - McDonnell LA, Heeren RM (2007). "Imaging mass spectrometry". Mass spectrometry reviews. 26 (4): 606–43. doi:10.1002/mas.20124. PMID 17471576.
- Chaurand P, Norris JL, Cornett DS, Mobley JA, Caprioli RM (2006). "New developments in profiling and imaging of proteins from tissue sections by MALDI mass spectrometry". J. Proteome Res. 5 (11): 2889–900. doi:10.1021/pr060346u. PMID 17081040.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Walch, A., Rauser, S., Deininger, S. O., & Hofler, H. (2008). MALDI imaging mass spectrometry for direct tissue analysis: a new frontier for molecular histology. Histochemistry and cell biology, 130(3), 421-434. doi:10.1007/s00418-008-0469-9
- Andersson M, Groseclose MR, Deutch AY, Caprioli RM (2008). "Imaging Mass Spectrometry of Proteins and Peptides: 3D Volume Reconstruction". Nature Methods. 5 (1): 101–108. doi:10.1038/nmeth1145. PMID 18165806.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Sinha TK, Khatib-Shahidi S, Yankeelov TE, Mapara K, Ehtesham M, Cornett DS, Dawant BM, Caprioli RM, Gore JC (2008). "Integrating Spatially Resolved Three-Dimensional MALDI IMS with in vivo Magnetic Resonance Imaging". Nature Methods. 5 (1): 57–59. doi:10.1038/nmeth1147. PMC 2649801. PMID 18084298.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Norris, Jeremy L.; Caprioli, Richard M. (10 April 2013). "Analysis of Tissue Specimens by Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry in Biological and Clinical Research". Chemical Reviews. 113 (4): 2309–2342. doi:10.1021/cr3004295.
- Hanreider, J.; Ljungdahl, A.; Faelth, M.; Mammo, S. E.; Bergquist, J.; Andersson, M. (2011). Mol. Cell. Proteomics. 10.
{{cite journal}}: Missing or empty|title=(help) - Nilsson, Anna; Fehniger, Thomas E.; Gustavsson, Lena; Andersson, Malin; Kenne, Kerstin; Marko-Varga, György; Andrén, Per E.; Morty, Rory Edward (14 July 2010). "Fine Mapping the Spatial Distribution and Concentration of Unlabeled Drugs within Tissue Micro-Compartments Using Imaging Mass Spectrometry". PLoS ONE. 5 (7): e11411. doi:10.1371/journal.pone.0011411.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Hankin, J. A.; Barkley, R. M.; Murphy, R. C. (2007). J. Am. Soc. Mass Spectrom. 18: 1646.
{{cite journal}}: Missing or empty|title=(help) - Spraggins, Jeffrey M.; Caprioli, Richard M. (2011). "High-Speed MALDI-TOF Imaging Mass Spectrometry: Rapid Ion Image Acquisition and Considerations for Next Generation Instrumentation". J. Am. Soc. Mass Spectrom. 22: 1022-1031. doi:10.1007/s13361-011-0121-0.
- Caldwell RL, Caprioli RM (2005). "Tissue profiling by mass spectrometry: a review of methodology and applications". Mol. Cell Proteomics. 4 (4): 394–401. doi:10.1074/mcp.R500006-MCP200. PMID 15677390.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - Reyzer ML, Caprioli RM (2007). "MALDI-MS-based imaging of small molecules and proteins in tissues". Current Opinion in Chemical Biology. 11 (1): 29–35. doi:10.1016/j.cbpa.2006.11.035. PMID 17185024.
- Woods AS, Jackson SN (2006). "Brain tissue lipidomics: direct probing using matrix-assisted laser desorption/ionization mass spectrometry". The AAPS journal. 8 (2): E391–5. doi:10.1208/aapsj080244. PMC 3231574. PMID 16796390.
- Stoeckli M, Staab D, Schweitzer A (2006). "Compound and metabolite distribution measured by MALDI mass spectrometric imaging in whole-body tissue sections". International Journal of Mass Spectrometry. 260 (2–3): 195–202. doi:10.1016/j.ijms.2006.10.007.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Khatib-Shahidi S, Andersson M, Herman JL, Gillespie TA, Caprioli RM (2006). "Direct Molecular Analysis of Whole-body Animal Tissue Sections by Imaging MALDI Mass Spectrometry". Analytical Chemistry. 78 (18): 6448–6456. doi:10.1021/ac060788p. PMID 16970320.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
Further reading
- Francese S, Dani FR, Traldi P, Mastrobuoni G, Pieraccini G, Moneti G (February 2009). "MALDI mass spectrometry imaging, from its origins up to today: the state of the art". Comb. Chem. High Throughput Screen. 12 (2): 156–74. doi:10.2174/138620709787315454. PMID 19199884.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Richard M. Caprioli, Terry B. Farmer, and Jocelyn Gile (December 1997). "Molecular Imaging of Biological Samples: Localization of Peptides and Proteins Using MALDI-TOF MS". Anal. Chem. 1997. 69 (23): 4751–4760. doi:10.1021/ac970888i. PMID 9406525.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
External links
- MALDI MS-imaging interest group
- DFG (German Research Foundation) National Core Facility for MALDI MS-imaging