A rapid and reliable CE-LIF method for the quantitative analysis of miRNA-497 in plasma and organs and its application to a pharmacokinetic and biodistribution study.

MicroRNAs (miRNAs) are involved in the pathogenesis of many human diseases, and various miRNAs have been reported and developed as therapeutic candidates for treating various diseases. Various miRNA and carrier modification systems have been investigated for effective systemic miRNA delivery to cells, organs, and tissues of interest. Consequently, effective and reliable analytical methods of miRNAs are required for evaluating the pharmacokinetics and biodistribution of miRNAs as therapeutic candidates. The capillary electrophoresis with laser-induced fluorescence (CE-LIF) method has been recently reported as a promising and relatively rapidly developing tool with the potential to provide highly sensitive and specific analysis of biological molecules including miRNAs. Here, the CE-LIF method was used for application in the pharmacokinetic and distribution studies of miRNA-497 as a model miRNA for a lung target; miRNA-497 hybridized with 6-FAM-labeled DNA probes were separated using CE-LIF and detected within 6 min without any interference. This method showed a wide calibration range of 1.0-50 nM and 0.1-50 nM for plasma and the four organs, liver, spleen, lung, and kidney, respectively, with acceptable precision and accuracy. Using CE-LIF, the miRNA-497 level was evaluated in rat plasma and organs after intravenously administering 1 mg ml of a miRNA-497 mimic. Hence, miRNA-497 displayed a relatively short half-life of 1.76 h and was delivered to the lungs but mainly accumulated in the liver and spleen. This study evaluated the pharmacokinetics and biodistribution of the miRNA-497 mimic using CE-LIF for the first time and suggested the need for further studies to extend the half-life and conduct lung-targeted delivery of miRNA-497.