Abstract
The application of locked nucleic acid chemistry for microRNA detection by in situ hybridization, and thereby visualization of microRNA expression at single-cell resolution, has contributed to our understanding of the roles that these short noncoding regulatory RNAs play during development, physiology, and disease. Several groups have implemented chromogenic-based and fluorescence-based protocols to detect microRNA expression in formalin-fixed paraffin-embedded clinical tissue specimens. These emerging robust and reproducible tissue slide-based assays are valid tools to bring about the clinical application of in situ microRNA detection for routine diagnostics. Here, I describe a fully automated fluorescence-based four-color multiplex assay for co-detection of a microRNA (e.g., let-7a, miR-10b, miR-21, miR-34a, miR-126, miR-145, miR-155, miR-205, miR-210), reference RNA (e.g., U6 snRNA, 18S rRNA), and protein markers (e.g., CD11b, CD20, CD45, collagen I, cytokeratin 7, cytokeratin 19, smooth muscle actin, tubulin, vimentin) in FDA-approved Leica Bond-MAX staining station.