Impact of serum storage conditions on microRNA stability

Abstract

As microRNAs (miRNAs) were found to be present in human serum in a remarkably stable and cell-independent form, their potential as novel noninvasive biomarkers for physiological and pathophysiological conditions, including cancer, is of growing interest.1, 2 Serum miRNAs can be found in exosomes3 and bound to proteins, such as AGO2,4 increasing their stability and circulation time. However, owing to limited space and availability of −80 °C freezers, many hospitals and laboratories store patient serum samples at −20 °C, for many years. We therefore investigated the impact of short-term, intermediate-term and long-term storage at −80 and −20 °C on the stability and abundance of individual and total miRNAs in human serum.