Tissue microarrays (TMAs) represent a relatively high-throughput tool that enables the analysis of hundreds of unique tissue samples simultaneously. This method significantly reduces inter-sample variability as well as the amount of time, tissue, and reagents required as compared with conventional marker screening methods.
A TMA consists of a paraffin block with an array of tissue cores from control and diseased tissues. Multiple cores from each patient specimen are included in a TMA block design to improve sampling accuracy and screening reliability. Incorporation of multiple cores helps eliminate errors related to tumor/disease sample heterogeneity. A minimum of two to six replicate tissue samples from the same morphologic area are inserted in the array to compensate for losses during processing, as well as to provide multiple samples for assay validation. Sections are cut from the TMA block for new assay development or reagent validation. Every fiftieth section is stained with H&E to confirm histology and provide a visual quality assurance mechanism.
Three examples of TMAs include:
- Multi-tumor Arrays, featuring multiple samples from multiple patients, representing multiple tumor types (e.g., colon cancers, lung cancers, and prostate cancers), all in one block;
- Progression Arrays, containing multiple samples from a disease at various stages of disease progression (e.g., different grades and stages of prostate adenocarcinoma); and
- Outcome Arrays, which may contain samples from similar histologic types of a disease, but from patients who have had different clinical outcomes (e.g., responders vs. non-responders to a particular therapy).
TARPS has developed TMAs for most common tumors. In addition, TARPS has available developed and partially annotated TMAs from cancer cases provided by the University of Pittsburgh to The Cancer Genome Atlas (TCGA) project. Learn more about these TMAs and how to request slides.
The TMAs are annotated with de-identified clinical and pathologic information and provided to the investigators. In addition, our software tools provide data storage and retrieval, thus allowing interesting data mining studies to evaluate utility of the markers under study through univariate and multi-variate analyses.
TMAs are ideal for efficient screening of putative biomarkers using a variety of techniques including immunohistochemistry, fluorescence in situ hybridization of nucleic acids (FISH), and RNA in situ hybridization. These techniques are used in tumor profiling, rapid screening of gene amplifications and translocations in cancer, for verification in tissue of differentially expressed genes that have been identified by cDNA arrays, and for screening potential prognostic and diagnostic markers.
The TARPS TMA lab performs staining for tissue localization and target validation studies, and can refer you to laboratories that perform microscopy-based analyses upon request.