Circulating MicroRNAs: Methodological Aspects in Detection of These Biomarkers.

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs that regulate ex- pression of protein-coding genes involved in impor- tant biological processes and (patho)physiological states. Circulating miRNAs are protected against degradation, indicating their relevant biological func- tions. Many studies have demonstrated an associa- tion of the specific profile of circulating miRNAs with a wide range of cancers as well as non-malig- nant diseases. These findings demonstrate the impli- cation of circulating miRNAs in the pathogenesis of diseases and their potential as non-invasive disease biomarkers. However, methods for measurement of circulating miRNAs have critical technical hotspots, resulting in a discrepancy of the reported results and difficult definition of consensus disease biomarkers that may be implicated in clinical use. Here, we re- view functions of circulating miRNAs and their ab- errant expression in particular diseases. Further, we discuss methodological aspects of their detection and quantification as well as our experience with the methods.