Stability of β-Actin mRNA in Plasma

Authors


Address for correspondence: Prof. R. Swaminathan, Department of Chemical Pathology, 5th floor, North Wing, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK. Voice: +44-020-7928-9292x3542; fax: +44-020-2928-4226. r.swaminathan@kcl.ac.uk

Abstract

It has long been thought that mRNA is labile and easily prone to degradation. However, a recent study demonstrated that GAPDH mRNA in cell-free plasma may remain stable up to 24 hours after blood collection. As there are no other independent studies, we attempted to reproduce the findings of that study. In our study, blood was collected from a healthy male volunteer into Vacutainer tubes containing EDTA. Blood samples were placed on ice and plasma separated by double-centrifugation at times 0, 1, 2, and 5 hours after blood collection. mRNA was extracted from four aliquots of the blood sample by means of the QIAamp Viral RNA kit. Extracted mRNA was converted to cDNA by reverse transcription before real time quantitative PCR measurement of the housekeeping β-actin gene. Plasma β-actin mRNA at 2 hours (0.012; 0.0031–0.0297, median and range) was significantly lower (P= 0.022) than at 0 hours (0.12; 0.057–0.165) (P= 0.016). The levels decreased further at 5 hours (0.0037; 0.0024–0.011) (P= 0.004). The results show that plasma β-actin mRNA levels decrease with time after blood collection and that this is likely to be due to degradation in vitro.

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