(514e) Targeted PEGylated Liposomes for DNA Delivery Specific to α5β1 Integrin Bearing Cancer Cells

We devised a targeted stealth liposomal vesicle encapsulating condensed plasmid DNA to specifically deliver the payload to cancer cells bearing the α₅β₁ integrin. For the targeting molecule we used the fibronectin mimetic PR_b peptide (KSSPHSRN(SG)₅GRGDSP) that has been previously shown by our group to outperform both GRGDSP and fibronectin in in vitro cell binding experiments. The targeting effect of calcein encapsulated liposomes functionalized with PR_b and polyethylene glycol (PEG) has been previously demonstrated by our group in CT26 colon cancer cells. In the present study, we have combined the DNA packaging and intracellular release properties of cationic polymers with the protective and targeting properties of our PR_b targeted PEGylated liposomes to formulate an efficient gene delivery vehicle. We evaluated different cationic polymers (poly-L-lysine, branched polyethyleneimine, and linear polyethyleneimine) in their ability to condense DNA and transfect cancer cells. We characterized the DNA encapsulated liposomal formulations for size, charge, and surface concentration of targeting ligands, and put emphasis on the purification techniques to remove any unencapsulated DNA. PEGylated liposomes functionalized with PR_b outperformed other targeted and non-targeted liposomal formulations in transfecting CT26 cells in vitro and in vivo.