Direct Intercellular Vesicle Exchange between Adjacent Cells
Intercellular communication plays a central role in the development and integrity of multicellular organisms. Vesicle transfer, especially through extracellular space, has recently been highlighted as a critical intercellular communication modality, carrying nucleic acids, proteins, and others to distant cells. Previously, we demonstrated that extracellular vesicles induce "phenotypic synchronization of cells (PSyC)" during stem cell differentiation. While examining the mechanism underlying PSyC, we discovered a novel form of cellular communication mediated by direct intercellular vesicle exchange (DIVE) between adjacent cells across the plasma membrane (PM). By achieving cell-wide and high-spatiotemporal resolution imaging of vesicles labeled with fusion proteins of CD63 or CD81 to StayGold, a photostable fluorescent marker, we observed small vesicles (50-500 nm in diameter) directly transferred between adjacent cells. These vesicles moved at approximately 1 {micro}m/s and crossed PM in approximately 10-20 seconds. Furthermore, multiple vesicles traversed nearly identical sites of PM, suggesting the presence of specific routes or structures, potentially including a pore, mediating the vesicle transfer. Three-dimensional electron microscopy provided supportive observations for traversing vesicles with single membrane. These vesicles, named InterCellular Vesicles (InterCVs), were observed to colocalize with nucleic acids, including mRNA, microRNA, and DNA, suggesting the exchange of nucleic acid-mediated information, potentially inducing PSyC, between adjacent cells. Our discovery, DIVE, reveals a previously unknown modality of cell-cell communication, with the potential to reshape our understanding of cellular biology.