Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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Comparing the MicroRNA spectrum between serum and plasma.

Author(s): Wang K, Yuan Y, Cho JH, McClarty S, Baxter D, Galas DJ

Publication: PLoS One, 2012, Vol. 7, Page e41561

PubMed ID: 22859996 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to compare levels of circulating miRNA in blood components and to examine potential differences associated with the real-time PCR panel manufacturer on levels of miRNA in plasma and serum. Matched serum and EDTA plasma were obtained from 12 healthy patients and for 6 of these patients RBCs, Plts and WBCs were also obtained. miRNA was extracted using the miRNeasy kit. miRNA levels were quantified in 10 paired serum and plasma specimens, and 6 matched RBC, WBC and Plts specimens using Exiqon panels and in 6 paired serum and plasma specimens using Taqman panels. Only 4 plasma and serum specimens were quantified by both platforms.

   Summary of Findings:

   RNA concentrations were highest in RBCs followed by WBCs, Plts, serum and then plasma. Interestingly, the electropherogram of the RNA was similar among Plts, plasma and serum, but distinct from that of RBCs and WBCs. Of the 742 miRNA assayed, 178 were nondetectable in any of the specimens, 206 were detected in blood cell components (RBC, WBC and Plt) and 80 were detected in all specimen types (RBC, WBC, Plt, plasma and serum). While 26 miRNA were only found in RBCs, only 1 miRNA (miR-24-5p) was found exclusively in WBCs. Serum generally had higher levels of individual miRNA than plasma and expressed more miRNA types, but the difference in levels was only significant when assayed using Exiqon panels (p=0.0379). Of the 742 miRNA assayed using Exiqon panels, 90 and 99 miRNAs were detected in all 6 plasma and serum specimens, respectively, and 83 were detected in every plasma and every serum specimen. The greatest variability in miRNA levels was observed in  miR-22 in plasma and miR-29c in serum, while miR-92a and miR-720 were the least variable in plasma and serum, respectively. Of the 384 miRNA assayed by TaqMan panels, 106 and 118 miRNA were detected in all 6 plasma and serum specimens, respectively, and 98 were detected in every plasma and every serum specimen. The greatest variability in miRNA levels quantified with TaqMan panels was observed with miR-101 and miR-576-3p in plasma and serum, respectively, while miR-185 miR-345 were the least variable in plasma and serum, respectively. While 358 miRNA were assayed using both real-time qPCR panel types, only 67 miRNA were detected in all plasma and serum specimens using both platforms. The average CT value was 6.7 cycles lower using Taqman than Exiqon panels, although the opposite was true for several miRNAs. miRNA levels measured by Taqman were weakly correlated with those measured by Exiqon (R2=0.3136 for serum and R2=0.3236 for plasma). Importantly, U6, RNU44 (SNORD 44) and RNU48 (SNORD48), which often serve as controls, were not detected in all plasma, serum, Plt, RBC or WBC specimens and when expressed were highly variable. The authors report no association between patient age or gender and RNA concentration, or number of detectable miRNA using either platform. However, the authors report gender-dependent expression of some miRNA, and cited higher levels of miR-130b and miR-18b in serum from males compared to females as an example.

   Biospecimens

   • Bodily Fluid - Plasma
   • Bodily Fluid - Serum
   • Cell - White Cells
   • Cell - Red Blood Cells
   • Bodily Fluid - Blood

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   RNA	Low density array
   RNA	Automated electrophoresis/Bioanalyzer
   RNA	Real-time qRT-PCR

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Serum Red blood cells Leukocyte Platelets
   Preaquisition	Patient gender	Female Male
   Low density array Specific	Targeted nucleic acid	miR-24-5p U6 RNU44 RNU48 (SNORD48) miR-130b miR-18b miR-22 miR-29c miR-92a miR-720 miR-101 miR-185 miR-576-3p miR-345
   Low density array Specific	Type of array	TaqMan low density arrays Exiqon low density arrays
   Preaquisition	Patient age	22-41 years

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