Does Centrifugation Cause the ex Vivo Release of DNA from Blood Cells?

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Abstract
Using a sex-mismatched bone marrow transplantation model, we have previously demonstrated that hematopoietic cells represent the predominant origin of cell-free plasma DNA ( 1). In that study, plasma samples were obtained by high-speed centrifugation followed by high-speed microcentrifugation. The comparison of the total DNA concentrations in plasma obtained by centrifugation and microcentrifugation for different numbers of times revealed no significant difference. We therefore concluded that centrifugation is not associated with damage to blood cells and artificial increases in cell-free plasma DNA concentrations. However, there remains a possibility that the first spin might have already destroyed blood cells, leading to the ex vivo release of DNA. This theoretical possibility might produce an aberrantly high proportion of cell-free plasma DNA originating from hematopoietic cells. In fact, to prevent cell lysis, the use of low-speed centrifugation, at 500g or even lower, has been a usual practice in harvesting blood cells ( 2)( 3). We therefore investigated the effect of the use of different centrifugation speeds on the quantification of plasma DNA.