Absolute Quantification of Mitochondrial DNA in Peripheral Blood from Women with Preeclampsia

Introduction Mitochondrial DNA (mtDNA) in maternal blood has been proposed as a potential predictor of preeclampsia (PE). The objective of this study was to use an absolute PCR (abPCR) quantification protocol to determine concentrations of mtDNA in maternal plasma and peripheral blood mononuclear cells (PBMC) from normal and PE pregnancies. Methods Blood samples were collected from pregnant women with uncomplicated pregnancies and pregnancies with PE (University of Iowa IRB#200910784). abPCR quantification of mtDNA and nDNA was performed on DNA extracts from plasma (in the presence or absence of lysis buffer) and PBMCs using TaqMan(TM) probes and chemistry. Results When plasma DNA was extracted using lysis buffer, mtDNA concentrations were lower in women with PE than in controls (Control: 4.83 ± 1.09 vs. PE: 1.72 ± 0.38 pg/uL, n=19, P=0.017), while concentrations of nDNA did not differ (P=0.39). Without lysis buffer, plasma mtDNA remained lower in women with PE compared to controls (Control: 0.0106 ± 0.0019 vs PE: 0.0019 ± 0.0003 pg/uL, n=16-20, P< 0.0001). There were no group differences in PBMC mtDNA (P=0.66) and nDNA (P=0.13) concentrations. Conclusion mtDNA concentrations were lower in plasma of pregnant women with PE compared to controls. A significant amount of mtDNA was membrane bound as indicated by a 480-fold greater concentration in DNA isolated from plasma with lysis buffer vs. without. Use of this improved method of quantification of mtDNA in multiple blood fractions may allow for its development as a biomarker to detect PE prior to the onset of organ damage.