Analysis of circulating microRNA: preanalytical and analytical challenges

Area of Science:

• Biochemistry
• Molecular Biology
• Clinical Diagnostics

Background:

• Circulating microRNAs (miRNAs) are of significant interest as potential disease biomarkers.
• Clinical translation of miRNA biomarkers necessitates rigorous characterization of preanalytical and analytical parameters.

Purpose of the Study:

• To assess the stability and variability of circulating miRNAs in serum and plasma.
• To evaluate the impact of preanalytical factors like hemolysis and processing on miRNA quantification.

Main Methods:

• Serum and plasma samples from healthy volunteers were used for miRNA extraction.
• Reverse-transcription quantitative PCR (RT-qPCR) was employed to amplify specific miRNAs (miR-15b, miR-16, miR-24, miR-122).
• Nested ANOVA was used to assess assay variation, stability, and the effect of hemolysis and control miRNA addition.

Main Results:

• Plasma exhibited higher miRNA concentrations than serum; processing reduced plasma miRNA levels to serum levels.
• Selected miRNAs demonstrated stability under refrigeration/freezing (72h) and room temperature (24h).
• Hemolysis artifactually increased concentrations of three tested miRNAs, and extraction/interassay imprecision contributed most to variability, unaffected by exogenous controls.

Conclusions:

• Thorough validation of preanalytical steps is critical for reliable miRNA biomarker detection and quantification.
• Mitigating sources of imprecision is essential for clinical utility, otherwise only significantly altered miRNAs will be suitable biomarkers.