Tissue Microarrays: A Current Medical Research Tool

Iqbal S. Shergill; N. K. Shergill; M. Arya; H. R. H. Patel

Disclosures

Curr Med Res Opin. 2004;20(5) 

In This Article

History of Discovery

In 1986, Hector Battifora described a 'sausage' block method,[7] in which 1 mm thick 'rods' of tissue, obtained from different specimens, were wrapped carefully in a sheet of small intestine. This 'sausage' of tissues was embedded in a paraffin wax block, from which numerous sections were cut. Subsequently, this technique was modified from a 'sausage-block' to a 'checkerboard' configuration.[8] Although this technique conferred a significant advantage of simultaneously examining multiple tissue specimens under identical conditions, the inability to satisfactorily identify individual 'rods' limited any meaningful interpretation. These limitations were addressed subsequently, and in 1998, the TMA was first reported by Kononen et al.[9]

The stepwise production of a TMA (Figure 1) starts with obtaining the original histopathological blocks - the donor blocks. As these blocks are invariably stored in archives, it is recommended that a fresh section is cut onto a standard microscope slide and stained with Haematoxylin and Eosin (H&E). The area of study interest, commonly an area of cancer, is marked on the H+E section (Figure 2), in conjunction with an experienced histopathologist. The TMA is then ready to be arrayed. A TMA instrument, such as that from Beecher Instruments,[10] is used to acquire a tissue core from the donor block. This core is then placed in an empty paraffin block - the recipient block. As the instrument has a precision X-Y guide on it, the core can be placed at a specifically assigned coordinate, which is accurately recorded, typically on a spreadsheet, such as Microsoft Excel. The sampling process can then be repeated many times from different donor blocks until hundreds, or even thousands, of cores are placed into one recipient block, producing the final TMA block (Figure 2). Following construction of the array block, 200-300 sections can be cut, with all the cores in an identical configuration (Figure 2), in preparation for subsequent morphological or molecular analysis. Subsequently, using a simple computer programme, such as Microsoft Excel, the locations of the cores on the TMA can be rapidly compared with clinical and pathological data.

Stepwise production of tissue microarray (TMA).

TMA construction.

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