(584ax) Encapsulation of Adenovirus With Pegylated Ternary Cationic Liposome Shows Improved Transduction of CAR-Negative Cells

Encapsulation of Adenovirus with PEGylated Ternary Cationic Liposome Shows Improved Transduction of CAR-Negative Cells

Sravanthi Vupputuri, Lobat Tayebi and Joshua D. Ramsey

School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078

Adenovirus (Ad) has been widely used in gene therapy clinical trials because of its ability to transduce different human cells and to accommodate large transgenes. Ad-based gene delivery vectors, however, have drawbacks, such as the inability to efficiently infect cells lacking the coxsackie adenovirus receptor and a tendency to elicit an inflammatory response, which initiates clearance of the virus. To address these drawbacks we explored encapsulating the virus in a PEGylated ternary cationic liposome (DDCP) composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), cholesterol and polyethylene glycol (PEG). We also investigated the effect of non-ionic surfactants and amino acids on the physical and chemical stability of the PEGylated liposomes.

Our results showed that encapsulation of Ad with PEGylated cationic liposomes enabled the virus to infect CAR-negative cells, providing an almost 300-fold improvement in gene expression compared to the native virus alone. We also found that gene expression depended on the ratio of the different lipids, with the optimum molar ratio of DDCP being 1.0:0.7:0.3:0.02. The level of proinflammatory cytokine IL-6 produced by mouse macrophage cells exposed to Ad encapsulated within the DDCP liposome was significantly lower than for cells exposed to the native virus. Further, measurements of cytotoxicity indicated that PEGylation provided a significant reduction in toxicity. Nanoparticle size, zeta-potential and polydispersity were characterized using dynamic light scattering. Overall, our results show that encapsulating Ad within PEGylated liposomes is an attractive option for producing an improved adenoviral vector with improved transduction of CAR-negative cells and reduced cytokine production.