Adhesion of phospholipid vesicles to Chinese hamster fibroblasts: Role of cell surface proteins

Abstract

The adhesion of artificially generated lipid membrane vesicles to Chinese hamster V79 fibroblasts in suspension was used as a model system for studying membrane interactions. Below their gel-liquid crystalline phase transition temperature, vesicles comprised of dipalmitoyl lecithin (DPL) or dimyristoyl lecithin (DML) adsorbed to the surfaces of EDTA-dissociated cells. These adherent vesicles could not be removed by repeated washings of the treated cells but could be released into the medium by treatment with trypsin. EM autoradiographic studies of cells treated with [3H]DML or [3H]DPL vesicles showed that most of the radioactive lipids were confined to the cell periphery. Scanning electron microscopy and fluorescence microscopy further confirmed the presence of adherent vesicles at the cell surface.Adhesion of DML or DPL vesicles to EDTA-dissociated cells modified the lactoperoxidase-catalyzed iodination pattern of the cell surface proteins; the inhibition of labeling of two proteins with an -60,000-dalton mol wt was particularly evident. Incubation of cells with 3H-lipid vesicles followed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis showed that some of the 3H-lipid migrated preferentially with these 60,000-mol wt proteins.Studies of the temperature dependence of vesicle uptake and subsequent release by trypsin showed that DML or DPL vesicle adhesion to EDTA-dissociated cells increased with decreasing temperatures. In contrast, cells trypsinized before incubation with vesicles showed practically no temperature dependence of vesicle uptake.These results suggest two pathways for adhesion of lipid vesicles to the cell surface-a temperature-sensitive one involving cell surface proteins, and a temperature-independent one. These findings are discussed in terms of current models for cell-cell interactions.The biochemical and physical properties of cell surface membranes are of fundamental importance to our understanding of the complex phenomena underlying cell-cell interactions. One approach toward elucidating these properties is to substitute a synthetic membrane surface of known

Lipid-Based Drug Delivery Systems in Cancer Therapy: What Is Available and What Is Yet to Come

“…Pires et al (1999) demonstrated that liposomes made up of PC:PE displayed low cell-binding ability and extremely limited cell fusion, which suggested that neutral liposomes are internalized mainly by an endocytic mechanism. Although the exact endocytosis mechanism responsible for the uptake of neutral liposomes is still unclear, it has been speculated that such a mechanism may involve the binding of liposomes to a trypsin-sensitive site (Pagano and Takeichi, 1977). In fact, it was demonstrated that the interaction of neutral PC liposomes to Chinese hamster V79 fibroblasts could only be dissociated in the presence of trypsin (Pagano and Takeichi, 1977).…”

“…Although the exact endocytosis mechanism responsible for the uptake of neutral liposomes is still unclear, it has been speculated that such a mechanism may involve the binding of liposomes to a trypsin-sensitive site (Pagano and Takeichi, 1977). In fact, it was demonstrated that the interaction of neutral PC liposomes to Chinese hamster V79 fibroblasts could only be dissociated in the presence of trypsin (Pagano and Takeichi, 1977).…”

Liposome—glass interaction. Influence of the lipid bilayer phase state

“…The sharp decrease in the DPPC amount bound to the surface at the gel-liquid crystal transition (P~,-L~ fluidization, Fig. 4) correlates with some findings concerning cell adhesion: various types of cells adhere to solid lipid films but not to fluid films [20][21][22]; solid liposomes more strongly associated with cells than fluid liposomes [23,24]; fluidization of cell membranes reduces cell adhesiveness [7][8][9][10][11][12][13]. This, as well as the electron microscope investigation (Fig.…”

The interaction of Bacillus protoplasts with sonicated phosphatidylcholine liposomes

“…Adsorbed vesicles can be released by treatment with trypsin, but not by repeated washing [2,12]. In our case, trypsin failed to reduce the proportion of phosphatidylcholine bound to protoplasts (table 1).…”