Intracellular distribution of fluorescent probes delivered by vesicles of different lipidic composition.
In order to study mechanisms involved in liposome-cell interaction, this work attempted to assess the influence of vesicle composition on the delivery of liposomal content to Hela cells. In particular, to evaluate pH-sensitive properties and cell interaction of the prepared liposomes, the lipid formulations contained cholesterol (Chol) and they were varied by using phosphatidylcholines with different purity degree: soy lecithin (SL; 80% phosphatidylcholine), a commercial mixture of soy phosphatidylcholine (P90; 90% phosphatidylcholine) or dipalmitoylphosphatidylcholine (DPPC; 99% of purity). A second series of liposomes also contained stearylamine (SA). Dehydration-rehydration vesicles (DRV) were prepared and then sonicated to decrease vesicle size. Vesicle-cell interactions and liposomal uptake were examined by fluorescence microscopy using carboxyfluorescein (CF) and phosphatidylethanolamine-dioleoyl-sulforhodamine B (Rho-PE) as fluorescent markers. Fluorescence dequenching assay was used to study the influence of pH on CF release from the liposomal formulations. Liposome adhesion on the cell surface and internalization were strongly dependent on vesicle bilayer composition. SA vesicles were not endocytosed. DPPC/Chol liposomes were endocytosed but did not release their fluorescent content into the cytosol. SL/Chol and P90/Chol formulations displayed a diffuse cytoplasmic fluorescence of liposomal marker.
Manconi
Maria
M
Dipartimento Farmaco Chimico Tecnologico, Università di Cagliari, Via Ospedale 72, Cagliari, Italy.
Isola
Raffaella
R
Falchi
Angela Maria
AM
Sinico
Chiara
C
Fadda
Anna Maria
AM
D005456:Fluorescent Dyes / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D050356:Lipid Metabolism; D008081:Liposomes; D008856:Microscopy, Fluorescence
D005456:Fluorescent Dyes; D008081:Liposomes