From left: Quek Jia Min, Dr Chung Ka Yan and Dr Neo Shu Hui
Shu Hui Neo1, Ka Yan Chung1, Jia Min Quek1 & Heng-Phon Too1,2
1 Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore
2 Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
Published in Scientific Reports 2017 7(1): 16686 (Online Version)
The availability of high-quality biospecimens is fundamental for biomarker discovery and the development of protocols for preserving nucleic acids in clinical specimens is critical for accurate molecular testing. MicroRNAs (miRNAs) have recently emerged as promising biomarkers in liquid biopsy for cancer diagnostics and therapies. One of the major challenges is to be able to store and distribute biological samples without the need for complicated and costly infrastructures and resources. A highly cost-effective approach is to store blood samples on paper matrix, Flinders Technology Associates (FTA) Elute cards.
In this study, we performed a comprehensive evaluation of FTA Elute cards for miRNA storage and recovery in different pre-analytical conditions, which includes collection, processing and storage stability. The recovery of serum miRNA dry-spotted on FTA Elute cards and direct elution with water at high temperature was unacceptably poor. Using an off-the-shelf lysis reagent, the recovery of serum and exosomal miRNAs were improved (~ 40% yield). This recovery was further enhanced with FTA Elute cards pre-treated with trehalose where the yield of miRNAs was more than 80%. We then determined the clinical utility of FTA Elute cards by quantifying miRNAs of dry-spotted gastric cancer (GC) patient serum. Furthermore, we demonstrated a previously unreported use of FTA Elute card in miRNA extraction from dry-spotted serum exosomes, marking a potential for paper matrix to store and detect serum exosomal miRNAs. Taken together, we have developed a highly cost-effective and robust method to archive and retrieve miRNAs from serum or serum exosomes dry-spotted on a paper matrix where the representation in expression levels was retained quantitatively. This method is easily incorporated into clinical studies, facilitating the transport of specimens across laboratories for diagnostics.
Figure 1. miRNA recovery from serum-spotted FTA Elute cards was improved upon pre-treatment with trehalose.
20 µl serum was spotted directly on an untreated (black) or trehalose-treated (white) 6mm FTA Elute card disc punch-out before QIAzol lysis reagent-mediated extraction. 10 miRNAs were quantified and individual % miRNA recovery was calculated.