Formalin-fixed, paraffin-embedded approaches

Shi S-R, Liu C, Perez J, et al. Protein-embedding technique a potential approach to standardization of immunohistochemistry for formalin-fixed, paraffin-embedded tissue sections. J. Histochem. Cytochem. 2005 53 1167-1170. 

As documented by numerous publications, the key factor of heat-induced AR is high temperature heating formalin-fixed, paraffin-embedded (FFPE) tissue sections in water solution. For some antigens, certain optimized pH value of the AR solution and/or adjusted temperature may be required to reach the best result by the use of the test battery approach mentioned above. In 2005, Namimatsu et al. reported a novel AR solution containing 0.05% citraconic anhydride, pH 7.4, for heating FFPE tissue sections at 98°C for 45 min to... 

An alternative approach to assessing tissue-specific expression at the proteomic level can be achieved by MS of laser capture microdissected tissues.4 An important development in this arena is the ability to perform LCM and MS/MS on formalin-fixed paraffin-embedded tissues. 

The preparations most often affixed to silane- (9) or poly-L-lysine-coated slides are Carnoy-fixed suspensions of metaphase cells for chromosome studies (see Chapter 47) cytospins of cultured cells followed by methanol fixation sections of formalin-fixed, paraffin-embedded tissues and frozen sections fixed with acetone or ethanol/acetic acid after cutting. Each of these approaches imparts different intracellular effects that may modify cytological detail and/or hybridization. (See Chapters 8 and 9 for a discussion of fixatives and frozen-section preparations.)... 

Background Since its introduction 15 years ago, imaging of tissues by MALDI has rapidly expanded to include peptides, proteins, multiple classes of lipids, as well as small molecules such as metabolites and xenobiotics. Tissues examined have ranged from frozen tissue sections to formalin-fixed paraffin-embedded sections, and have been obtained from a wide variety of sources, including from whole animals to specific tissues, e.g., kidney and eye lens, as well as normal and diseased states. While TOF (and TOF/TOF) remains the most frequently used technique, other approaches, including MS/MS using QTOF, trap-TOF, ion mobility, and FT-trap formats, have also been reported. This paper describes analysis of tissue sections from the whole body to subsections of tissues, down to the cellular level. 

The staining protocol and differences in pretreatment methods are an important factor when formalin-fixed and paraffin-embedded material is nsed, as not all antibodies work satisfactorily under these conditions. Several different approaches can be found in the literature. Heat-induced antigen retrieval by the use of microwave heat treatment has been demonstrated to be more effective in labeling intraneuronal Ap compared to no or enzymatic pretreatment [29]. Information on the use of FA is inconsistent. It is widely used to increase the immunoreactiv-ity of amyloid plaques in AD however, it has been shown that the effect on intraneuronal Ap is low and that use of FA sometimes results in a loss of cellular detail [30]. A recent study tried to quantify the effect of FA pretreatment and analyzed plaque load and intraneuronal Ap immunoreactivity using an APi, antibody in 6-month-old APP/PSIKI mice (Fig. 3 reproduced from [25] with permission from Elsevier). 

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