Figure 4. Freeze/thaw of standard plasma increased miRNA abundance in platelet poor plasma (PPP).

(A) Select miRNAs were measured in PPP with or without an intermediate freeze/thaw cycle. miR-21, -27b, and -425 were markedly elevated after freeze/thaw, while the red blood cell specific miR-451 was not significantly different. (B) The platelet contribution of select miRNAs to standard plasma was calculated by subtracting the normalized relative expression (2^{−(Ct miR-Ct Cel-39)}) in PPP from the relative expression in standard plasma and expressed as a fraction of the whole. With the exception of miR-451, these miRNAs are expressed at much greater levels in platelets than in the extracellular environment.