Fig. 4
From: Evaluation of RNA isolation methods for microRNA quantification in a range of clinical biofluids
Differences in heparin sensitivity between isolation methods is only observed in body fluids. Biofluids were spiked with increasing amounts of unfractionated heparin. Ten μl of a half-log dilution series containing the indicated IU of heparin were added to the samples prior to RNA isolation. Cel-miR-39 for loss during work-up (A, B, C) and cel-miR-54 as indicator of co-purified RT-qPCR inhibiting compounds (D, E, F) were determined in RNA from preservation fluid (fresh UW) (A, D), or from the body fluids serum (B, E), and urine (C, F), using method RN (miRNEAsy kit, black circles/solid lines) and method NG (Norgen kit, black squares/dotted lines). Heparin amounts are shown on the x-axis. The area of unreliable detection is indicated in grey. Detection levels are calculated from Cq values using the following equation: detection levels = 2(−Cq)× 109. In serum and urine, the inhibitory effect of heparin is approximately ten times higher with the RN method compared to NG method as indicated by arrows. No difference was observed for both spiked-in cel-miR-39 and cel-miR-54 isolated from fresh UW using method NG or RN. ***: p < 0.001, nonlinear regression (curve fit) comparison for dose-response data