Droplet digital polymerase chain reaction-based quantification of circulating microRNAs using small RNA concentration normalization

Sci Rep. 2020 Jun 2;10(1):9012. doi: 10.1038/s41598-020-66072-z.

Abstract

Quantification of plasma microRNAs (miRNAs) as non-invasive disease biomarkers is subject to multiple technical variabilities. This study aimed to develop an optimized protocol for miRNA quantification from rodent plasma. We hypothesized that a fixed small RNA concentration input for reverse transcription (RT) reaction will provide better miRNA quantification than a fixed RNA volume input. For this, tail-vein plasma was collected from 30 naïve, adult male Sprague-Dawley rats. Plasma hemolysis was measured with NanoDrop-1000 and Denovix DS-11 spectrophotometers. Plasma was then pooled, and RNA was extracted from 50-μl, 100-μl or 200-μl pool aliquots. Small RNA concentration was measured with Qubit miRNA assay. A fixed RNA volume (un-normalized) or a fixed small RNA concentration was used for RT (concentration-normalized). The method was setup with miR-23a-3p and validated with miR-103a-3p and miR-451a. Hemolysis measurements from Denovix and NanoDrop strongly correlated. Qubit revealed increased small RNA concentrations with increasing starting plasma volumes. With concentration-normalization, miRNA levels from 100-µl and 200-µl plasma volume groups mostly normalized to the level of the 50-µl in ddPCR. Our results indicate that miRNA quantification with ddPCR should be performed with small RNA concentration-normalization to minimize variations in eluted RNA concentrations occuring during RNA extraction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Circulating MicroRNA / blood*
  • Circulating MicroRNA / isolation & purification
  • Edetic Acid
  • Hemolysis
  • Male
  • MicroRNAs / blood
  • Plasma
  • Polymerase Chain Reaction / methods*
  • Rats, Sprague-Dawley
  • Reproducibility of Results

Substances

  • Circulating MicroRNA
  • MIRN103 microRNA, rat
  • MIRN23 microRNA, rat
  • MIRN451A microRNA, rat
  • MicroRNAs
  • Edetic Acid