Effects of Transport Inhibitors on the Internalization of Cellular Vesicles by Different Breast Cancer Cell Lines

Liposomes are spherical vesicles composed of natural or artificial lipids and are used as drug carriers. However, their surface needs modification with ligands to target specific tissues. Cell-derived vesicles (CVs) are bioinspired drug carriers, as they are derived from cells by physical methods. Therefore, they preserve the topology and composition of the molecules present in the plasma membrane of the parental cell, enabling in vivo organotropism and specific drug delivery. The aim of this study is the investigation of the mechanisms by which liposomes and autologous CVs are internalized by three different breast cancer cell lines. The elucidation of the mechanism is likely to result in their optimization as drug carriers and the comprehension of their sub-cellular fate. More specifically, liposomes and CVs were produced, characterized, and loaded with the fluorescent dye FITC-dextran. Uptake experiments were performed using inhibitors of the clathrin-dependent or caveolin-dependent endocytic pathways and after incubating the cells at 4 °C, where energy dependent processes are inactivated. The results indicate that the endocytosis of CVs is active, mainly via the caveolin pathway, whereas liposomes are internalized actively by both pathways and also passively, as their uptake at 4 °C is not significantly hampered.