Background: In the past few years, an increasing number of studies have reported the potential use of
microRNAs (miRNA) as circulating biomarkers for diagnosis or prognosis of a wide variety of diseases.
There is, however, a lack of reproducibility between studies. Due to the high miRNA content in platelets
this may partly be explained by residual platelets in the plasma samples used. When collecting fresh
plasma samples, it is possible to produce cell-free/platelet-poor plasma by centrifugation. In this study,
we systematically investigated whether biobanked EDTA plasma samples could be processed to be
suitable for miRNA analysis.
Materials and methods: Blood samples were collected from ten healthy volunteers and centrifuged to
produce platelet-poor-plasma (PPP) and standard biobank plasma. After one week at 80 °C the biobanked EDTA plasma was re-centrifuged by different steps to remove residual platelets. Using RT-qPCR
the levels of 14 miRNAs in the different plasma preparations were compared to that of PPP.
Results: We were able to remove residual platelets from biobanked EDTA plasma by re-centrifugation of
the thawed samples. Nevertheless, for most of the investigated miRNAs, the miRNA level was significantly higher in the re-centrifuged biobanked plasma compared to PPP, even when the platelet count
was reduced to 0–1 109/L.
Conclusion: We found, that pre-storage centrifugation conditions have a significant impact on the
measured EDTA plasma level of miRNAs known to be present in platelets. Even for the miRNAs found to
be less effected, we showed that a 1.5–3 fold change in plasma levels may possible be caused by or easily
overseen due to sample preparation and/or storage.
& 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND