The exosome exchange

Cells send RNA messages to each other by packing them into tiny membrane vesicles called exosomes, according to Hadi Valadi, Jan Lötvall (Göteborg University, Göteborg, Sweden), and colleagues. The study uncovers a new mechanism of genetic exchange between cells.

Exosomes form from the inward budding of vesicles into endosomes. If an endosome later fuses with the plasma membrane, its exosome packets can be released into the extracellular space. In this way, exosomes have been shown to send signals and present antigens to recipient cells. Proteins within the exosomes' bellies and on their surfaces have been the main focus of study, but nobody had looked to see whether exosomes contained nucleic acids, explains Lötvall.

His team now finds that exosomes isolated from immune cells known as mast cells contain large amounts of RNA, including translatable mRNA. DNA, however, was not...