Technologies for Detection of miRNAs as Biomarkers
Several molecular diagnostic technologies have been used for detection of miRNAs PCR, LNA, in situ hybridization (ISH) and microarrays. miRNAs are biomarkers and measurement of miRNA has diagnostic value for diseases as well, particularly cancer.
Microarrays for Analysis of miRNA Gene Expression
miRNA gene expression profiling can be done on microchips containing oligonucleotides corresponding to miRNAs from human and mouse genomes. Such microarrays have been used to obtain highly reproducible results that reveal tissue-specific miRNA expression signatures, data that is confirmed by assessment of expression by Northern blots, real-time RT-PCR, and literature search. The microchip oligoli- brary can be expanded to include an increasing number of miRNAs discovered in various species and is useful for the analysis of normal and disease states. Basic analysis of miRNA genes in different mouse tissues and embryo stages using semiquantitative approaches shows tissue-restricted and developmentally restricted expression patterns of miRNAs. Newer microarray formats in development include many brain- and ESC-specific genes.
NCode™ Array (Life Technologies) enables sensitive profiling of miRNAs while using extremely simple methods that provide both experienced and novice microarray users a rapid path to new discoveries. NCode™ Rapid miRNA Labeling System (Life Technologies) combines its Alexa Fluor® fluorescent dyes with Genisphere Inc's 3DNA® dendrimer signal amplification technology, which is based on highly branched DNA structures serving as scaffolds for multitudes of fluorescent dyes. Development of this simple process to efficiently couple miRNAs directly to 3DNA® dendrimers is a significant improvement over past methods and overcomes the problem of working with small nucleic acids, where sensitivity is often limited. The new kit will accelerate the discovery of novel miRNA biomarkers. NCode™ enables researchers to study miRNA function by allowing them to profile the miRNA expression patterns in a given disease or developmental state. This will be used in molecular diagnostics and drug discovery. Sensitive microarrays to survey full sets of miRNAs in neural stem cells during differentiation, both in culture and in vivo, enabled the detection of novel patterns of regulated miRNAs systematically. An understanding of these unexpected regulatory mechanisms provides novel targets for potentially managing or controlling differentiation in stem cells prior to therapeutic transplantation.
mirVana™ System (Life Technologies) is used for miRNA microarray profiling. It involves isolation of total RNA, extraction and labeling of miRNA, and this is followed by hybridization and analysis. miRNA arrays speed up biomarker discovery and unique markers have been identified for various diseases. High-throughput detection and differential expression analysis of miRNA by microarray technology, may contribute to a greater understanding of the many events regulated by these molecules.