[Standardization of Plasma Preparation for MicroRNA Analysis: Influences of High Speed Centrifugation and Membrane Filtration].

MicroRNAs (miRNA) are non-coding small RNAs. Exosomes carry extracellular miRNAs in plasma and other body fluids. Levels of plasma miRNAs show disease-specific changes. Thus, miRNAs are expected to be new biomarkers in many diseases. However, the method of analysis of plasma miRNAs is not well established. In this study, we tested the influences of high speed centrifugation and membrane filtration on results from plasma miRNA analysis using reverse transcriptase-based quantitative polymerase chain reac- tion (RT-qPCR). We studied plasma from 12 normal subjects. The level of plasma miR-451 did not change significantly after high speed centrifugation and filtration, rather showed slight increment, 1.543 ± 0.263 fold (mean±SD, N=3). The levels of plasma miR-126 and miR-223 decreased with high speed centrifugation and filtration, (0.038 ± 0.008 fold and 0.041 ± 0.003 fold, respectively). Our data suggested that removing platelets and cellular debris from plasma with high speed centrifugation and/or filtration is essential for stand- ardization of plasma miRNA analysis. [Original].