MicroRNA levels quantified in whole blood varies from PBMCs

MicroRNAs are non-coding RNAs that negatively regulate mRNA expression and play significant roles in both health and disease. Differential microRNA expression has been used to aid diagnosis and discriminate disease stages. The accuracy and reliability of microRNA expression measurement is of utmost importance. Quantification of microRNA expression in human peripheral blood is commonly detected using total RNA extracted via different methods. To date, no convincing data are available showing whether microRNA quantification results can be influenced by the use of total RNA extracted from whole blood or peripheral blood mononuclear cells (PBMCs). This study examined miR-146a-5p and miR-155-5p expression using total RNA extracted in parallel from whole blood and PBMCs of 14 healthy volunteers. The data showed that the quantification of miRNA using total RNA extracted from whole blood varied from that of PBMCs, indicating that the miRNA expression was a result of all the different cell-types present in whole blood. Our results suggested that the source of total RNA and the statistical analyses performed are crucial considerations when designing miRNA research.