Blood microRNAs (miRNAs) are ideal biomarkers, and blood derivatives are often collected in the scope of miRNA research projects. However, knowledge of temporal variations of miRNAs in healthy individuals is lacking. In this study, miRNA variability was measured over a 1-year period in different blood derivatives, collected every 2-3 months from two healthy donors. There is a continuum of intraindividual temporal variability, with particularly stable (coefficient of variation [CV] <20%-30%) and particularly unstable (CV >100%-130%) miRNAs in serum, plasma, and specific white blood cell subpopulations. The temporal intraindividual variability of miRNAs should be taken into consideration in experimental design of biospecimen collections and validation of diagnostic biomarkers.
Keywords: blood cells; miRNA; plasma; serum; stability.