Reviewed by James Ives, MPsych Human cells shed exosomes. These tiny extracellular, membrane-bound vesicles can carry cargo for cell-to-cell communication, ferrying diverse loads of proteins, lipids or nucleic acids. University of Alabama at Birmingham and Chinese researchers now report that exosomes are key to the SOS signal that the heart muscle sendsout after a heart attack. After the heart attack, the exosomes in the bloodstream carry greatly increased amounts of heart-specific microRNAs — an observation seen in both...