Assessment of Trizol-Based Method for Isolating Small RNAs from Plasma

Small RNAs (sRNA), associated with various biological processes, exhibit altered expressions in relation to pathology. Many of these are stable in the body fluids as circulating sRNAs and serve as potential biomarkers for various diseases such as cancer, neurodevelopment and cardiovascular diseases. Although numerous highly sensitive methods exist to detect the expression of small RNA in plasma, the low input RNA quantity and stability with high cost would be a challenge for the detection. In this study, the Trizol-based method for isolating sRNAs from plasma, which can address these problems, would be evaluated by extraction efficiency and stability. The efficiency of large RNA removal and sRNAs recovery was analyzed by the brightness of the spike-in RNAs bands and the %CtCV result of the representative sRNA after going through the extraction procedure. With respect to method stability, the extraction would be evaluated by the %CV of the RNA concentration measured by the nanodrop machine between replicates, as well as by the %CtCV of the small representative RNA (miR-16). As a result, the Trizol-based method has shown that the large RNA (>200 nt) was considerably reduced (≥90%) and sRNAs (≤200 nt) was highly recovered (~99.3%). The total extracted RNA concentration was stable with the average A260/280 of 1.7 ± 0.21 and CV% at 7.1%. The quantity of the representative sRNA, miR-16, had a low dispersion among replicates with %CV of 6.7%. Therefore, the Trizol-based method is suggested to apply for sRNA extraction from plasma.