Serum cell-free DNA released from postmortem subjects

Abstract Background Cell-free DNA (cfDNA) is DNA released from dying cells into the serum. In this study, the origin and mechanism of cell-free DNA (cfDNA) release in postmortem subjects were evaluated by measuring the levels of M30, M65, cyclophilin A (CyPA), and myeloperoxidase (MPO) to evaluate the origin of cfDNA. Methods Serum (n = 54) was sampled from postmortem autopsied Japanese subjects.cfDNA was extracted and M30, M65, CyPA, and MPO in serum were assayed by enzyme-linked immunosorbent assay. Results Significantly higher serum levels of M30, M65, and MPO were observed in postmortem subjects than in living subjects. Although the difference was smaller, CyPA was also significantly higher in postmortem subjects than in living subjects. In addition, serum M30 and MPO levels were significantly correlated with cfDNA concentrations in postmortem subjects. Moreover, M30 levels slightly increased according to the postmortem interval, while M65 levels were slightly higher with a 1.5-day postmortem interval. ConclusionElevated levels of cfDNA in postmortem subjects are released by apoptosis and neutrophils via NETosis, that apoptosis is highly induced according to the postmortem interval, and that necrosis and NETosis are continually induced.