Abstract

exRNA Biomarkers: Challenges in Methodology

Srimeenakshi Srinivasan, Research Fellow, University of California, San Diego

The study of exRNAs and their roles in biological functions and potential biomarkers require robust and reproducible methods for quantification of exRNAs in biofluids, a task that is made more challenging by multiple sources of technical and biological variability. A number of factors including the variety of cells/tissues from which the exRNAs are produced, the low concentrations of exRNAs in the biofluids, the presence nucleases and association with multiple different extracellular compartments impact the reproducibility of exRNA measurements, and are likely a significant reason that the field has encountered difficulties with validation of findings both within and among different research groups. Here we compare various exRNA isolation methods used on standardized samples in multiple laboratories and evaluate their performance using qRT-PCR and small RNA sequencing. The results show that different methods enrich for different subsets of exRNAs depending on their association with extracellular carriers and the reproducibility of each method varies widely. Thus selection of the RNA isolation method is a critical consideration to be taken into account when planning a study to identify exRNA biomarkers.