Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells
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Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-7 Biomechanics, 52428 Jülich, Germany
2
Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), 85748 Garching, Germany
3
Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-2 Theoretical Soft Matter and Biophysics, 52428 Jülich, Germany
*
Author to whom correspondence should be addressed.
Nanomaterials 2019, 9(7), 1025; https://doi.org/10.3390/nano9071025
Received: 6 June 2019 / Revised: 12 July 2019 / Accepted: 12 July 2019 / Published: 17 July 2019
Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs or many types of biological macromolecules, including DNA and proteins. Efficiency and speed of cargo delivery are especially high for carrier vesicles that fuse with the cellular plasma membrane. This occurs for lipid mixture containing equal amounts of the cationic lipid DOTAP and a neutral lipid with an additional few percents of an aromatic substance. The fusion ability of such particles depends on lipid composition with phosphoethanolamine (PE) lipids favoring fusion and phosphatidyl-choline (PC) lipids endocytosis. Here, we examined the effects of temperature, ionic strength, osmolality, and pH on fusion efficiency of cationic liposomes with Chinese hamster ovary (CHO) cells. The phase state of liposomes was analyzed by small angle neutron scattering (SANS). Our results showed that PC containing lipid membranes were organized in the lamellar phase. Here, fusion efficiency depended on buffer conditions and remained vanishingly small at physiological conditions. In contrast, SANS indicated the coexistence of very small (~50 nm) objects with larger, most likely lamellar structures for PE containing lipid particles. The fusion of such particles to cell membranes occurred with very high efficiency at all buffer conditions. We hypothesize that the altered phase state resulted in a highly reduced energetic barrier against fusion.
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Keywords:
cationic liposomes; membrane fusion; lipid phases; fusion conditions
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Description: Figure S1. Fluorescence and phase contrast micrographs of CHO cells upon treatment with fusogenic (FLs) (DOPE/DOTAP/TFPE-head 1/1/0.1 mol/mol) and endocytic (ELs) (DOPC/DOTAP/TFPE-head 1/1/0.1 mol/mol) liposomes. Cellular intercalation of the liposomes was verified by an additional washing step with a heparine solution. Uptake efficiencies are shown in the micrographs (%). Green: TFPE-head signal, red: nucleic staining with DRAQ5. Scale bar, 50 µm. Table S1. Temperature dependence of the fusion efficiencies of liposomes containing the cationic lipid DOTAP, different helper lipids, and TFPE-chain or DiR as an aromatic molecule (1/1/0.1 mol/mol). Efficiencies of endocytosis and fusion give a sum of 100%. Average values of at least three independent measurements and their standard deviations are given. Table S2. Fusion efficiencies of liposomes containing the cationic lipid DOTAP, different helper lipids, and TFPE-chain or DiR as dye molecule (1/1/0.1 mol/mol) depending on the osmolarity and ionic strength of the buffer. Efficiencies of endocytosis and fusion give a sum of 100%. Average values of at least three independent measurements and their standard deviations are given.
MDPI and ACS Style
Kolašinac, R.; Jaksch, S.; Dreissen, G.; Braeutigam, A.; Merkel, R.; Csiszár, A. Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells. Nanomaterials 2019, 9, 1025. https://doi.org/10.3390/nano9071025
AMA Style
Kolašinac R, Jaksch S, Dreissen G, Braeutigam A, Merkel R, Csiszár A. Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells. Nanomaterials. 2019; 9(7):1025. https://doi.org/10.3390/nano9071025
Chicago/Turabian StyleKolašinac, Rejhana; Jaksch, Sebastian; Dreissen, Georg; Braeutigam, Andrea; Merkel, Rudolf; Csiszár, Agnes. 2019. "Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells" Nanomaterials 9, no. 7: 1025. https://doi.org/10.3390/nano9071025
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