Profiling MicroRNA Markers in Plasma: Looking into Better Approaches and Recommendations.

The revelation of stable microRNA (miRNA) species in body fluids has led to the speculation of disease-related alterations in miRNA expression levels as indicative of disease state making them attractive minimally invasive biomarkers for the diagnosis and prognosis of cancer and other diseases. Although miRNA expression profiling in body fluids holds great promise, working with low amounts of RNA in plasma and serum represents several challenges during purification, relative quantification, normalization, and data analysis. Here, we present an experimental protocol for miRNA profiling in plasma using plasma/serum-specific miRNA purification and RT-qPCR to identify potential miRNA biomarkers. We also discuss the challenges encountered during the miRNA profiling process and provide recommendations for robust purification and relative quantification of miRNAs in patient plasma samples.