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Lipid Vesicle-mediated Affinity Chromatography using Magnetic Activated Cell Sorting (LIMACS): a Novel Method to Analyze Protein-lipid Interaction
Published on: April 26, 2011
The in vitro kinetics of the interactions between PEG-ylated magnetic-fluid-loaded liposomes and macrophages
Marie-Sophie Martina1, Valerie Nicolas, Claire Wilhelm
1Equipe Physico-Chimie des Systèmes Polyphasés, CNRS UMR 8612, F-92296 Châtenay-Malabry Cedex, France.
Abstract:
Binding and uptake kinetics of magnetic-fluid-loaded liposomes (MFL) by endocytotic cells were investigated in vitro on the model cell-line J774. MFL consisted of unilamellar phosphatidylcholine vesicles (mean hydrodynamic diameter close to 200nm) encapsulating 8-nm nanocrystals of maghemite (gamma-Fe(2)O(3)) and sterically stabilized by introducing 5mol% of distearylphosphatidylcholine poly(ethylene glycol)(2,000) (DSPE-PEG(2,000)) in the vesicle bilayer. The association processes with living macrophages were followed at two levels. On one hand, the lipid vesicles were imaged by confocal fluorescence microscopy. For this purpose 1mol% of rhodamine-marked phosphatidylethanolamine was added to the liposome composition. On the other hand, the iron oxide particles associated with cells were independently quantified by magnetophoresis. All the experiments were similarly performed with PEG-ylated or conventional MFL to point out the role of polymer coating. The results showed cell association with both types of liposomes resulting from binding followed by endocytosis. Steric stabilization by PEG chains reduced binding efficiency limiting the amount of MFL internalized by the macrophages. In contrast, PEG coating did not change the kinetics of endocytosis which exhibited the same first-order rate constant for both conventional and PEG-ylated liposomes. Moreover, lipids and iron oxide particle uptakes were perfectly correlated, indicating that MFL vesicle structure and encapsulation rate were preserved upon cell penetration.
Insights
Polymer coating on magnetic-fluid-loaded liposomes (MFL) affects cell binding but not endocytosis kinetics. PEGylation reduces MFL uptake by macrophages, impacting drug delivery strategies.
Area of Science:
- Biomedical Engineering
- Materials Science
- Cell Biology
Background:
- Liposomes are versatile drug delivery vehicles.
- Magnetic-fluid-loaded liposomes (MFL) offer targeted delivery potential.
- Understanding MFL-cell interactions is crucial for optimizing their use.
Purpose of the Study:
- To investigate the binding and uptake kinetics of MFL by macrophages.
- To evaluate the impact of polyethylene glycol (PEG) coating on MFL-cell interactions.
- To determine if MFL structure is maintained during cellular uptake.
Main Methods:
- Utilized J774 macrophage cell line for in vitro studies.
- Prepared MFL with maghemite nanocrystals and DSPE-PEG(2,000) for steric stabilization.
- Employed confocal fluorescence microscopy and magnetophoresis to track MFL association and iron oxide uptake.
- Compared PEG-ylated MFL with conventional MFL.
Main Results:
- Both conventional and PEG-ylated MFL associated with macrophages via binding and endocytosis.
- PEGylation significantly reduced MFL binding efficiency and subsequent internalization.
- Endocytosis kinetics remained unchanged by PEG coating, with a similar first-order rate constant.
- Lipid and iron oxide uptake were correlated, indicating preserved MFL integrity post-internalization.
Conclusions:
- Steric stabilization with PEG impacts the initial binding phase of MFL to macrophages.
- PEG coating modulates MFL cellular association without altering the fundamental endocytosis mechanism.
- MFL maintain their structural integrity during cellular uptake, preserving encapsulation efficiency.
