Role of Mechanical Properties of Cell Mediated Vesicles in Membrane Fusion

Abstract

Cell mediated vesicles (CMVs) are endogenous particles involved in cell to cell communication. CMVs transport proteins and RNA and offer multiple advantages over conventional drug delivery systems. For example they are naturally stable in the body and could have natural targeting properties. Synthetic generation of liposomes with similar characteristics to CMVs could result in cost-effective drug carriers including all advantages CMVs offer. Interestingly, most CMVs contain large amounts of cytoskeletal proteins: actin and tubulin, but also related cross linkers and motor proteins. We hypothesize that the cytoskeletal elements present in these vesicles contribute to their efficient fusion with cells. In our study we compare three kinds of vesicles: natural vesicles excreted by blood cells (both erythrocytes and dendritic cells), empty liposomes and liposomes containing actin filaments. First we visualize the structure of these three types with fluorescent imaging and AFM. Furthermore, we indent the vesicles using AFM to learn about the mechanical properties of these small vesicles. These results, in combination with single vesicle fusion assays, will reveal the role of the cytoskeleton in vesicle fusion.