Quantification of peripheral whole blood, cell-free plasma and exosome encapsulated mitochondrial DNA copy numbers in patients with atrial fibrillation

Soltész, B.a, Urbancsek, R.b, Pös, O.c, Hajas, O.b, Forgács, I.N.b, Szilágyi, E.a, Nagy-Baló, E.b, Szemes, T.c, Csanádi, Z.b, Nagy, B.a

aDepartment of Human Genetics, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
bInstitute of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
cDepartment of Molecular Biology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia

Abstract

Mitochondrial DNA (mtDNA) copy number changes have been associated with various diseases. Several studies showed that mtDNA content in peripheral bloodwas associated with oxidative stress and cardiovascular disease. Atrial fibrillation (AF) is one of the severe cardiovascular diseases. We aimed to determine the mtDNA copy numbers in peripheral blood, in cell-free plasma and in exosomes of AF patients and healthy controls.

Peripheral blood was drawn from 60 AF patients and 72 healthy controls. DNA was isolated from EDTA blood and plasma. Exosomes were isolated from cell-free plasma and then exosome encapsulated DNA (exoDNA) was extracted. Quantitative-real-time PCR was performed with Human Mitochondrial DNA (mtDNA) Monitoring Primer Set. Statistical analysis of the data was performed.

We found statistically significant difference in mtDNA copy numbers in DNA isolated from peripheral whole blood, cell-free plasma and exosome samples of controls’ (44.4 ± 18.0, 27.2 ± 30.1, 11.5 ± 8.7), and patients’ group (43.4 ± 13.6, 26.2 ± 26.4, 14.5 ± 12.3). However there was no significant difference in mtDNA copy number between the two study groups either in peripheral blood, in cell-free plasma and in exosomes, and even in different sexes and ages.

We found the highest copy number of mtDNA in peripheral blood, followed by plasma and exosomes. We did not find differences between patients and controls, neither age nor gender had effect on the mtDNA copy number. According to our results the mtDNA copy numbers did not differ in AF patients.