Evaluation

Evaluation of a low-cost procedure for sampling, long-term storage, and extraction of RNA from blood for qPCR analyses

Maerkedahl, Rasmus B.; Frokiaer, Hanne; Lauritzen, Lotte; Metzdorff, Stine B.

University of Copenhagen

Abstract

Background:
In large clinical trials, where RNA cannot be extracted immediately after sampling, preserving RNA in whole blood is a crucial initial step in obtaining robust qPCR data. The current golden standard for RNA preservation is costly and designed for time-consuming column-based RNA-extraction. We investigated the use of lysis buffer for long-term storage of blood samples for qPCR analysis.

Methods:
Blood was collected from 13 healthy adults and diluted in MagMAX lysis/binding solution or PAXgene Blood RNA tubes and stored at -20 °C for 0, 1, or 4 months before RNA extraction by the matching method. RNA integrity, yield and purity were evaluated and the methods were compared by subsequent analyses of the gene expression levels of 18S, ACTB, IL1B, IL1RN, IL1R2, and PGK1 using qPCR.

Results:
The MagMAX system extracted 2.3-2.8 times more RNA per mL blood, with better performance in terms of purity, and with comparable levels of integrity relative to the PAXgene system. Gene expression analysis using qPCR of 18S, ACTB, IL1B, IL1RN, IL1R2, and the promising blood-specific reference gene, PGK1, revealed negligible differences (<1-fold) between the samples stored in MagMAX lysis/binding solution over time and between samples stored and extracted by the two systems.

Conclusions:
The MagMAX system can be used for storage of human blood for up to 4 months and is equivalent to the PAXgene system for RNA extraction. It furthermore, provides a means for significant cost reduction in large clinical trials.