Microarrays paraffin tissue microarray

A low power view of a multi-tumor paraffin tissue microarray (TMA). 

Groseclose MR, Massion PP, Chaurand P, et al. High-throughput proteomic analysis of formalin-fixed paraffin-embedded tissue microarrays using MALDI imaging mass spectrometry. Proteomics 2008 8 3715-3724. 

In this technique (http //en.wikipedia.org/wiki/Tissue microarray), a hollow needle is used to remove tissue cores of various diameter (from as small as 0.6 4 mm) from regions of interest in paraffin-embedded tissues (clinical biopsies or tumor samples) (Figs. 13.10, 13.11). 

These tissue cores are then inserted in a recipient paraffin block (Fig. 13.12) in a precisely spaced array pattern. Each microarray block can be cut into from 100 to 1000 sections (Fig. 13.13), which can be subjected to independent tests with immunolabeling (Moch et al. 2001). 

Fig. 13.10 A tissue microarray instrument with a paraffin wax block...

Scicchitano MS, Dalmas DA, Bertiaux MA et al. Preliminary comparison of quantity, quality, and microarray performance of RNA extracted from formalin-fixed, paraffin-embedded, and unfixed frozen tissue samples. JHistochem Cytochem 2006 54 1229-1237. 

T.M. and Rimsza, L.M. (2007) Quantitative nuclease protection assay in paraffin-embedded tissue replicates prognostic microarray gene expression in diffuse large-B-cell lymphoma. Lab. Invest.,... 

Recent times have seen the advent of high throughput assays such as array comparative genomic hybridization and cDNA microarray, which have lead to the rapid discovery of thousands of potential biomarkers. However, these need to be validated in tissue-based studies in large datasets to prove their potential utility. As these datasets are typically present in the form of formalin fixed paraffin-embedded tissue blocks, immunohistochemical (IHC) methods are ideal for validation. However, performing whole-section IHC on hundreds to thousands of blocks requires lot of resources in terms of reagents and time. In addition, an average block will yield less than 300 slides of 5 pm each. The tissue microarray (TMA) technique circumvents some of these problems. 

Figure 1a. Principle of tissue microarray (TMA) analysis. Cylindrical cores are obtained from a number (up to 1,000) of individual formalin-fixed, paraffin-embedded tissue blocks. These are transferred to recipient TMA. Each TMA block can be sectioned up to 300 times. All resulting TMA slides have the same tissues in the same coordinate positions. The individual slides can be used for a variety of analyses saving labor and reagent costs while maintaining uniformity of assay.

Lugli A, Tornillo L, Mirlacher M, et al. Hepatocyte paraffin-1 expression in human normal and neoplastic tissues Tissue microarray analysis on 3,940 tissue samples. Am J Clin Pathol. 2004 122 721-727. 

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