Variations – Tissue microarray
Author: Rodney E. Shackelford, DO, Ph.D. (see Reviewers page)
Revised: 3 July 2010, last major update July 2010
Copyright: (c) 2008-2010, PathologyOutlines.com, Inc.
● Tissue microarray (TMA) significantly differs from the other techniques discussed in this chapter because the hybridization step involves antibody binding to one target protein, or nucleic acid hybridization to one target gene
● TMA allows for the simultaneous analysis of protein expression in up to 500 different tissue samples
● The relative level of a specific protein’s expression can be compared on the same slide, allowing uniform analysis
● A small amount of tissue is used per sample analyzed, allowing more analyses per same tissue volume and lowering the amount of tissue biopsied from patients
● TMA is cost effective as performing one TMA is far cheaper than performing many (up to several hundred) separate immunohistochemical analyses on glass slides
● TMA analysis directly measures proteins levels, thereby avoiding quantifications based on comparing different mRNA species that may be translated with different efficiencies
● To perform TMA, a hollow needle is used to obtain tissue cores as small as 0.6 mm in diameter
● Usually paraffin-embedded tissue from patient biopsies or surgical specimens is used
● The tissue cores are placed in a specific array within a paraffin block, sectioned, placed on a slide, and protein expression is quantified by standard immunohistochemistry
● Alternatively, FISH analysis can be used to identify the level of specific nucleic acid sequences
● TMA has been particularly valuable in analyzing protein expression in tumor samples
End of Molecular Pathology > Microarray > Variations > Tissue microarray
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