Urinary microRNA can be concentrated, dried on membranes and stored at room temperature in vacuum bags

Urine accumulates traces of changes that occur in the body and can potentially serve as a better biomarker source. Urinary microRNA is a promising class of non-invasive disease biomarkers. However, long-term frozen human urine samples are not a good source for the extraction of urinary microRNA. In this paper, we demonstrate that urinary microRNA can be concentrated, dried on membranes and stored in vacuum bags at room temperature for several months. The amount of total RNA on the membranes after storage at room temperature for three months was unchanged. The levels of miR-16 and miR-21 exhibited no significant differences (P = 0.564, 0.386). This simple and economical method makes the large-scale storage of clinical samples of urinary microRNA or other nucleic acids possible.