Tissue microarray technology is powerful. The technology yields gene expression profiles that are a window to tumor biology, oncology, and diagnostic test development (Shi et al, 2013). A microarray is defined as a supporting material onto which molecules or fragments of DNA or protein are attached in a regular pattern for use in biochemical or genetic analysis. Tissue microarrays (TMAs or tissue chips) are constructed of paraffin blocks comprising (up to 1,000) numerous discrete tissue cores assembled in array fashion for analysis by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and mRNA in situ hybridization.
The genesis of the tissue microarray (TMA) technology two decades ago was the discovery by Battifora et al in 1986 of how 1 mm thick rods of different tissues could be wrapped in a sausage-like sheet of small intestine and embedded in paraffin to form a multitumor tissue block (MTTB). The technique was refined as an array in 1987, and although simultaneous assessment of many tissue specimens at the same time under the same conditions was now feasible, the inability to pinpoint the nature of each tissue specimen remained problematical. By 1998, Kononen et al had further refined TMA to permit rapid construction of microarrays and commercialization of the TMA device. The popularity of the TMA device continues to increase with commercial marketing, first by Beecher Instruments, and currently by Estigen Tissue Science.