Tissue Microarray Technology and Its Potential Applications in Toxicology and Toxicological Immunohistochemistry

Advanced high-throughput post-genomic technologies are increasingly being applied in the areas of experimental and clinical medicine. Studies using genomic and transcriptomic approaches currently dominate the arena in every biomedical discipline. However, proteomic techniques are also gaining popularity in the basic and clinical settings. Tissue microarray (TMA) technology is essentially an extension of proteomics, enabling the simultaneous analysis of protein biomarkers in hundreds or thousands of tissue samples in an array format. TMAs are an ordered array of tissue cores on a charged glass slide. They permit immunohistochemical analysis of numerous tissue sections under identical experimental conditions. The arrays can contain samples of every organ in the human body, or a wide variety of common tumors and obscure clinical cases alongside normal controls. The arrays can also contain pellets of cultured cell lines. TMAs may be used like any histological section for immunohistochemistry or even in situ hybridization to detect protein and gene expression. The technology is inexpensive, fast, and statistically powerful. This new technology will allow investigators to analyze numerous biomarkers over essentially identical samples, develop novel prognostic markers, and validate potential drug targets. Therefore, it has substantial potential to facilitate translational research. Despite its impact on cancer research, this important technology has yet to fully penetrate into the area of toxicology. TMA technology is likely to have an increasingly important role in toxicology research. This chapter is intended to provide an introduction to TMA technology, summarize its strengths and weaknesses, and highlight its potential uses in toxicological immunohistochemistry.