Differential Nanoparticle Sequestration by Macrophages and Scavenger Endothelial Cells Visualized in Real-Time and at Ultrastructural Resolution.

Despite the common knowledge that the reticuloendothelial system is largely responsible for blood clearance of systemically administered nanoparticles, the sequestration mechanism remains a "black box". Using transgenic zebrafish embryos with cell type-specific fluorescent reporters and fluorescently labeled model nanoparticles (70 nm SiO), we here demonstrate simultaneous three-color imaging of intravenously injected nanoparticles, macrophages, and scavenger endothelial cells (SECs). The trafficking processes were further revealed at ultrastructural resolution by transmission electron microscopy.