Imaging tissue section

Magnetic resonance imaging (MRI) (Section 13 13) A diag nostic method in medicine in which tissues are examined by NMR... 

Figure 8.2 Design of protein-embedding barcode is depicted in (a) five thin layers of matrix (the thicker lines) coated with variable concentration of tested protein (thinner lines located above the matrix), (b) A FFPE tissue section of bladder cancer IHC-stained by monoclonal antibody to E-cadherine showing variable intensity of positive staining results which is compared with a protein-embedding bar code as designed in this chapter. Using computer-assisted image analysis with a special software, an automatic quantitative measurement of protein is performed. See color insert.

Lemaire R, Desmons A, Tabet JC, et al. Direct analysis and MALDI imaging of formalin-fixed, paraffin-embedded tissue sections. J. Proteome Res. 2007 6 1295-1305. 

The second method of sample preparation for IMS is a matrix-coating method for MALDI imaging. In this chapter, we review the choices of matrix compound and solvent composition appropriate for IMS of tissue sections. Three kinds of matrix-application methods and examples of their use are illustrated. 

The last sample preparation method for IMS is the transfer of a tissue section onto the PVDF membrane. Proteins in the section can be transferred onto the PVDF membrane and then analyzed on the membrane. The advantage of this method is that the enzyme can be digested for MS" measurement, because the information on protein localization in the organization is fixed on the membrane.5,20 This technique can denature, reduce, and digest the proteins in the tissue section efficiently and remove the salt from the tissue. This increases the efficiency with which biological molecules are ionized, making it possible to obtain sensitive mass imaging spectra. 

Stoeckli M, Staab D, Schweitzer A. Compound and metabolite distribution measured by MALDI mass spectrometric imaging in whole-body tissue sections. Int. J. Mass Spectrom. 2006 260 195-202. 

In a separate study, a protocol for Matrix-assisted laser desorption-ionization (MALDI) imaging mass spectrometry (IMS) has been proposed.18 This IMS technique provides a new approach to visualize spatial distribution of thousands of molecular species, including peptides, proteins, and their metabolites in two- or three-dimensional levels. This approach may also provide a straightforward method of determining the tissue distribution of multiple peptides or proteins in a quantitative manner.18 Chu et al.19 reported a nondestructive molecular extraction method to obtain proteins from a single FFPE or frozen tissue section, without destroying the tissue morphology, such... 

Chaurand P, Sanders ME, Jensen RA, et al. Proteomics in diagnostic pathology, profiling and imaging proteins directly in tissue sections. Am. J. Pathol. 2004 165 1057-1068. 

When coupled with an optical microscope, CL imaging is a potent analytical tool for the development of ultrasensitive enzymatic, immunohistochemistry (IHC) and in situ hybridization (ISH) assays, allowing spatial localization and semiquantitative evaluation of the distribution of the labeled probe in tissue sections or single cells to be performed. 

Imaging mass spectrometry involves MS performed on tissue sections mounted on a MALDI plate. The mass spectra generate images and an in situ protein expression profile of the specimen is analyzed. Specifically, the frozen tissue sections applied to a MALDI plate are subjected to laser interrogation and analyzed at regular spatial intervals. The mass spectral data obtained at different intervals are compared to generate a spatial distribution of masses (proteins) across the tissue section. 

---