PCR-free detection of microRNA-122 from serum – A platform comparison study between Luminex MAGPIX and FLEXMAP 3D

Background: MicroRNAs (miRNAs) are a crucial group of small, non-coding RNAs that regulate gene expression and participate in almost all biological processes, such as cell proliferation, differentiation, and apoptosis. Besides being important cellular regulators miRNAs have become useful biomarkers in diagnosis of numerous diseases [1]. The altered expression of individual miRNAs has been demonstrated in numerous cancers [1]. However, detecting and quantifying miRNAs accurately can be challenging, often relying on PCR amplification, which doesn’t allow direct analysis. Here, we are introducing a novel method for direct and PCR-free detection of microRNA-122 (miR-122) [2], a promising biomarker for liver function and liver disease diagnosis.
Methods: The current study describes a comparative performance assessment between Luminex MAGPIX® and FLEXMAP 3D® platforms to detect miR-122 in human serum. Experiments were performed under comparable conditions using DESTINA’s ChemiRNATM technology on the two Luminex platforms. Assay procedure: a) Modified capture probes (complementary to target miR-122) are conjugated onto Luminex microspheres; b) Microspheres are incubated with serum sample; c) Modified capture probes hybridize with miR-122, forming a chemical pocket; d) A modified base binds in the pocket which can be detected after the application of streptavidin-phycoerythrin. This comparative study has included six serum samples of liver-diseased individuals, as well as four control samples of symptom-free individuals, measured in triplicates and quantified using a 9-point standard curve.
Results: We observed FLEXMAP to be more sensitive in detecting miRNA-122 and resulting in higher signal intensities than MAGPIX. This result was not unexpected as MAGPIX measures fluorescence with CCD cameras after LED illumination of a single layer of microspheres, whereas FLEXMAP uses a flow cytometer-based technology in combination with lasers.
Conclusions: ChemiRNA™ Technology applied to Luminex microspheres enables direct quantification of miR-122 and can be used in combination with both platforms (MAGPIX and FLEXMAP) depending on given sensitivity requirements.