title: Release of bulk cell free DNA during physical exercise occurs independent of extracellular vesicles.
abstract: OBJECTIVE
  Strenuous exercise induces a rapid and transient elevation of cell free DNA (cfDNA) concentration in blood plasma. The detection of cfDNA in the presence of plasma nucleases could indicate an association of cfDNA with protective vesicular structures. Several cell types release extracellular vesicles (EVs), including exosomes and shedding microvesicles, which are known to mediate the exchange of proteins and nucleic acids (largely RNA) between cells. Here, we assessed whether EVs play a role in the exercise-dependent release of cfDNA in blood plasma.
  
  
  METHODS
  Venous blood collected from healthy volunteers before and after incremental treadmill exercise was separated into vesicular (EV) and soluble fractions. Nuclear and mitochondrial DNA content in plasma supernatants and EV fractions was determined by quantitative real-time PCR (qPCR).
  
  
  RESULTS
  We show that the majority of cfDNA is located in the plasma supernatants. Only minute amounts of DNA were observed in the EV-associated fractions including microvesicles and exosomes. Nuclear and mitochondrial DNA species differ in terms of their quantities in the several plasma fractions.
  
  
  CONCLUSIONS
  Our results indicate that cfDNA liberated in response to acute physical exercise is not released by vesicular means and circulates in a soluble form in blood plasma which could indicate different biological functions exerted by cfDNA and EVs. The different nature of DNA species in plasma has major implications for the preparation of plasma and other bodily fluids prior to analysis.
authors.affiliation: Department of Sports Medicine, Johannes Gutenberg-University Mainz, Albert-Schweitzer-Straße 22, 55128, Mainz, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Helmig
authors.affiliation: Molecular Cell Biology, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Frühbeis
authors.affiliation: Molecular Cell Biology, Johannes Gutenberg-University Mainz, Mainz, Germany.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Krämer-Albers
authors.affiliation: Department of Sports Medicine, Johannes Gutenberg-University Mainz, Albert-Schweitzer-Straße 22, 55128, Mainz, Germany.
authors.forename: Perikles
authors.initials: P
authors.lastname: Simon
authors.affiliation: Department of Sports Medicine, Johannes Gutenberg-University Mainz, Albert-Schweitzer-Straße 22, 55128, Mainz, Germany. tug@uni-mainz.de.
authors.forename: Suzan
authors.initials: S
authors.lastname: Tug
mesh_terms: D004247:DNA / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D000067128:Extracellular Vesicles / Q000378:metabolism; D006801:Humans; D008297:Male
chemical_list: D004247:DNA
keywords: Exercise; Extracellular vesicles; Mitochondrial DNA; cfDNA