Only limited sequencing data of the normal extracellular DNA (ecDNA) are currently available. The uptake of the ecDNA by cultured cells and its integration into the host chromatin have been demonstrated. A number of membrane-bearing vesicles in plasma and serum have been shown to carry nucleic acids. The presence of Tandem Repeat (TR) in both apoptotic DNA of HUVEC culture medium and membrane-associated DNA is shown. The existence and successful application of CREST serum also show the presence of fragments of the centromeric heterochromatin together with their TR and specific proteins in blood. Apparently, pericentromeric and centromeric DNA (TR) should be part of ecDNA in all cases.
Keywords: Apoptosis; Centromeric proteins; Extracellular DNA; Membrane-associated DNA; Tandem repeats.