MiRNA levels were normalized using either the exogenous celmiR-39 or the endogenous miR-16 as reference gene. When normalized to cel-miR-39, levels of miR-16 were found to be significantly (po0.05) higher in biobank A, A2 and B samples compared to PPP samples (1.6–2.6 fold in average). Therefore, the fold
changes in miRNA levels between the different plasma preparations and PPP found for the other investigated miRNAs were lowerwhen miRNA levels were normalized using miR-16 as compared to
normalization using cel-miR-39 (Table 1). Still, regardless of the
choice of normalization, we found significantly higher levels of all
the investigated miRNAs in biobank A/B samples compared to PPP
samples (po0.05), which was expected as these plasmas had
high/medium residual platelets content.