Quantitative Measurement of Cationic Polymer Vector and Polymer–pDNA Polyplex Intercalation into the Cell Plasma Membrane

• Published in: ACS nano Vol. 9; no. 6; pp. 6097 - 6109
• Main Authors: Vaidyanathan, Sriram, Anderson, Kevin B, Merzel, Rachel L, Jacobovitz, Binyamin, Kaushik, Milan P, Kelly, Christina N, van Dongen, Mallory A, Dougherty, Casey A, Orr, Bradford G, Banaszak Holl, Mark M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 23.06.2015
• Subjects: Cations - analysis; Cations - pharmacology; Cell Membrane - chemistry; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Membrane Permeability - drug effects; DNA - chemistry; Gene Transfer Techniques; Genetic Vectors - analysis; Genetic Vectors - pharmacology; HEK293 Cells; Humans; Intercalating Agents - analysis; Intercalating Agents - pharmacology; Particle Size; Polymers - analysis; Polymers - pharmacology; Porosity; Surface Properties; gene delivery; polymer−cell membrane interactions; polyplex−membrane partition; whole cell patch clamp; polymer-membrane partition; gene therapy; stable pore model
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.5b01263

Cationic gene delivery agents (vectors) are important for delivering nucleotides, but are also responsible for cytotoxicity. Cationic polymers (L-PEI, jetPEI, and G5 PAMAM) at 1× to 100× the concentrations required for translational activity (protein expression) induced the same increase in plasma membrane current of HEK 293A cells (30–50 nA) as measured by whole cell patch-clamp. This indicates saturation of the cell membrane by the cationic polymers. The increased currents induced by the polymers are not reversible for over 15 min. Irreversibility on this time scale is consistent with a polymer-supported pore or carpet model and indicates that the cell is unable to clear the polymer from the membrane. For polyplexes, although the charge concentration was the same (at N/P ratio of 10:1), G5 PAMAM and jetPEI polyplexes induced a much larger current increase (40- 50 nA) than L-PEI polyplexes (<20 nA). Both free cationic lipid and lipid polyplexes induced a lower increase in current than cationic polymers (<20 nA). To quantify the membrane bound material, partition constants were measured for both free vectors and polyplexes into the HEK 293A cell membrane using a dye influx assay. The partition constants of free vectors increased with charge density of the vectors. Polyplex partition constants did not show such a trend. The long lasting cell plasma permeability induced by exposure to the polymer vectors or the polyplexes provides a plausible mechanism for the toxicity and inflammatory response induced by exposure to these materials.