ABSTRACT
ISH is a molecular biological technique that allows direct analyses of both genes and gene expression, through the localization of specific DNA and mRNA sequences to individual cells within a morphologically preserved tissue. Messenger RNA (mRNA) ISH methods have been utilized for demonstrating the spatial distribution and heterogeneity of gene expression in the complex tissue structure. Messenger RNA ISH applications have an advantage over other molecular biological techniques in which homogenization precludes such morphologic evaluation. However, because of the lack of mRNA ISH protocol standardization, the reproducibility, specificity, and sensitivity of ISH results depend on a protocol performed in each research or clinical laboratory. Thus, the use of automated instruments for ISH applications can accelerate the standardization of ISH protocols. For post-genomic research activities, the automation of mRNA ISH protocols is a powerful tool for revealing the precise expression sites and patterns of newly discovered genes by high-throughput analyses. For clinical diagnostics, the establishment of automated mRNA ISH protocols delivers accurate and consistent results of the gene expression within a biopsy sample. In addition, because this technology can be applied to most routinely processed clinical formalin-
fixed, paraffin-embedded tissue samples, it is possible to retrospectively analyze the abnormalities in gene expression in large numbers of patient biopsy specimens. Thus, automated mRNA ISH applications would accelerate the research and development of new diagnostics biomarkers for pharmacogenomics.
