AbstractPlasma microRNA, which is relatively abundant compared to other extracellular RNA species, has drawn attention for its potential implication as biomarkers of various disease conditions. However, the great donor-to-donor variability of specific microRNA levels has been a challenging factor in their further development as a diagnostic biomarker assay. Also widely recognized, the levels of specific microRNAs are sensitive to sample collection, storage and extraction methods. Upon blood draw, the plasma microRNAome undergoes changes in concentration as well as in composition, mostly due to the in vitro blood cell breakdown. In this study, using different blood collection tubes including EDTA and Streck RNA Complete BCT, we compared microRNA extraction from the full plasma vs from isolated plasma exosomes. For each sample, we measured microRNA concentrations by global fluorometric assays and by quantitative PCR for specific microRNAs. The Streck tube minimizes the in vitro changes of microRNAome, thus facilitating detection of rare microRNAs originating from a distant diseased tissue.Citation Format: Eunju Seong, Nicholas M. George. Stability of draw-time microRNA concentration in blood collection tubes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4831.