Cellular binding, motion, and internalization of synthetic gene delivery polymers

Abstract

Using fluorescence microscopy we have tracked the cellular binding, surface motion, and internalization of polyarginine and polyethylenimine, cationic ligands used for gene and protein delivery. Each ligand was complexed with a quantum dot to provide a photostable probe. Transfection with exogenous DNA was used to relate the observed motion to gene delivery. Cell surface motion was independent of sulfated proteoglycans, but dependent on cholesterol. Cellular internalization required sulfated proteoglycans and cholesterol. These observations suggest that sulfated proteoglycans act as cellular receptors for the cationic ligands, rather than only passive binding sites. Understanding the interaction of polyarginine and polyethylenimine with the plasma membrane may assist in designing more efficient gene delivery systems.

Polyethylenimine Is a Strong Inhibitor of Human Papillomavirus and Cytomegalovirus Infection

“…It is generally accepted that polycations, including PEIs, bind to HSPGs (27,39,44,45). In mammals, syndecans and glypicans constitute the predominant cell surface HSPGs (5,20).…”

“…Primary attachment to target cells is mediated through binding to heparan sulfate proteoglycans for the majority of HPV types studied so far (46). It is generally accepted that HSPGs are also involved in the uptake of PEI-DNA polyplexes, suggesting that PEI directly interacts with HSPGs (27,39,44,45). Hence, it was conceivable that HPVs and PEI compete for the same primary attachment sites on cells and that inhibition of HPV infection by PEI was on the level of primary attachment.…”

“…Given their polycationic nature, PEIs have the capacity to condense with DNA, resulting in PEI-DNA complexes, and to mediate gene transfer into mammalian cells in vitro and in vivo (7). Cellular uptake of PEI-DNA complexes is dependent on heparan sulfate proteoglycans (HSPGs), which act as the interaction factor for PEI on the cell surface (27,39,44,45). PEIs range among the most potent transfection agents and hence constitute an interesting alternative to viral vectors for gene therapy (2,10,19).…”

Pyrenebutyrate-Mediated Delivery of Quantum Dots across the Plasma Membrane of Living Cells

“…The quantum dots used in these experiments have an average hydrodynamic diameter of 32 nm. 16 In comparison, green fluorescent protein (GFP) has a 3 nm hydrodynamic diameter and, presumably, a more flexible structure than a quantum dot. 32 To some extent, the large diameter of these quantum dots is due to the use of red-emitting quantum dots as red emission requires larger quantum dots than blue emission.…”

Chitosan and its derivatives as nanocarriers for siRNA delivery

“…This approach aims at enhancing, on one hand, the cationic charge of chitosan, thus potentiating its transfectability; and, on the other, improving the cytotoxicity of PLR by conjugation to chitosan. PLR has been described to mediate cellular uptake through its interaction with sulfated proteoglycans and cholesterol [116]. Chitosan complexed to siRNA showed a poor silencing efficiency compared to Lipofectamine TM 2000, chitosan-PLR and its pegylated counterpart, although it provided the best cell viability.…”