Recovery of MicroRNA from Stored Human Peripheral Blood Samples

Recovery of microRNAs (miRs) from tissue samples of many kinds has become an area of increasing interest and importance in recent years. We isolated and then amplified and quantitated miRs from human peripheral blood samples stored in the University of Colorado Denver Skin Cancer Biorepository to determine whether miR recovery was possible and consistent over time in storage. Forty-five blood samples from patients with different stages of malignant melanoma were collected in PAXgene Blood RNA tubes and then stored at -80°C prior to RNA preparation. The samples examined had been stored from 4 weeks to 3 years. Total RNA was prepared, followed by miR isolation, amplification, and quantitation using real-time polymerase chain reaction. A widely expressed miR, miR-221, was used as a standard for comparison across samples and storage time. miR-221 was recovered from all samples, with no differences observed with longer storage time. These studies show that miRs can be recovered and quantified from human blood samples stored for up to 3 years.