Evaluation of three rapid RNA extraction reagents: relevance for use in RT-PCR's and measurement of low level gene expression in clinical samples.

Although peripheral blood and bone marrow are usually readily available from patients, present techniques of RNA extraction are tedious, require millilitres of starting material and removal of red blood cells before RNA purification. Further, successful reverse transcriptase polymerase chain reaction (RT-PCR) amplification requires the removal of haemoglobin derivatives which interfere with the PCR process. Recently, one step rapid use reagents have become available, claiming to be useful for obtaining high quality RNA from microlitre quantities of whole blood drawn directly from the patient. Their use to date in clinical samples appears limited with little information in the literature documented. In an attempt to overcome this, we tested the Trizol-LS, RNA-STAT-50 and Ultraspec-3 reagents upon a statistically significant number of clinical isolates of fresh and cryopreserved peripheral blood, bone marrow, blood apheresis products and a breast cancer cell line (MCF7) in order to evaluate whether these methods could be applied to routine laboratory use in an RT-PCR method capable of detecting rare gene expression. Our findings showed that there was some variation in the quality of RNA extracted which was indicated by absorbance spectrophotometry at 260 and 280 nm. 1% agarose gel electrophoresis showed that each of these methods could yield total RNA capable of generating the signature 18S and 28S rRNA bands. Using the Kruskal-Wallis non-parametric anova test combined with Dunn's multiple comparison test, the only statistically significant difference (p<0.05) indicated that Trizol-LS was more reliable than RNA-STAT-50-LS and Ultraspec-3 at extracting RNA from fresh peripheral blood. RNA extracted with the Trizol-LS and RNA STAT-50 reagents was successfully amplified in a multiplex RT-PCR reaction for detection of the multi-drug resistance related genes MDR1, the multi-drug resistance related protein (MRP) and topoisomerase IIalpha. Low level MDR1 gene expression could be detected in frozen whole blood. However, PCR products were only seen when the anti-coagulant heparin was removed from all samples prior to cDNA production. RT-PCR amplification was not 100% successful with RNA extracted with Ultraspec-3 reagent. In conclusion, we found that the RNA extracted from whole blood with the Trizol-LS and the RNA-STAT-50 are suitable for use in clinically relevant molecular biology protocols that analyze rare event genes without further purification. Our results indicated that the Trizol-LS reagent was generally more consistent in obtaining a pure and sufficient quantity of RNA from patient material as shown by the mean result of purity and quantity in comparison to either Ultraspec-3 or RNA-STAT-50-LS reagents. Ultraspec-3 is not easily suited for direct use with whole blood products.