Modified high-throughput quantification of plasma microRNAs in heparinized patients with coronary artery disease using heparinase

Heparin, a widely used anticoagulant in cardiovascular diseases, is notorious for its inhibitory effect on qRT-PCR-based detection. Heparinase I could degrade heparin in RNA. qRT-PCR-based TaqMan Low Density Array (TLDA) technology is commonly used for circulating microRNAs (miRNAs) profiling analysis. However, the effect of heparin contamination on inhibition of miRNAs TLDA amplification, as well as the method for removing heparin during this process, are not yet well investigated. We obtained the plasma RNA samples from patients undergoing percutaneous coronary intervention (PCI) before and after heparinization (n = 26). We found that heparin suppressed the miRNAs amplification by ∼8 cycles in the TLDA assay, which was absolutely reversed after treating the RNA samples with heparinase I using the components from TLDA reverse transcription system. We further observed that heparin inhibited the miRNAs amplification by ∼4 cycles in the qRT-PCR assay, which was also reversed by heparinase I using the similar method. Furthermore, we demonstrated that plasma miR-92a and miR-155 were differentially expressed in the patients undergoing PCI tested by TLDA assay, which was validated by qRT-PCR. In conclusion, we present a simple method for the removal of heparin with heparinase I, and for the subsequent successful miRNAs TLDA or RT-qPCR amplification.