Prostasomal DNA characterization and transfer into human sperm

Human prostasomes, exosome-like microvesicles secreted by acinar cells of the prostate gland, contain chromosomal DNA. Agarose gel electrophoresis of DNA from seminal prostasomes displayed fragments of over 12 kb and smaller, with a distinct band around 1 kb that was excised, cloned, and sequenced. The sequences showed 8 out of 25 clones (32%) originating from genes. We elaborated the concept further by carrying out a genome-wide DNA copy number analysis of prostasomal DNA, hypothesizing that human prostasomes contain fragments of DNA randomly selected from the entire genome. Acridine orange-stained prostasomes were incubated with freshly prepared sperm for different times, and a transfer of acridine orange-stained prostasomal DNA to sperm (preferentially the head region) was observed. Fluorescence microscopy of slices in the center of 14 optical slides of the sperm head displayed an even fluorescence rather than a halo-like one, indicating DNA-uptake rather than just binding along the sperm head membrane.