Exploring the potential of novel pH sensitive lipoplexes for tumor targeted gene delivery with reduced toxicity

The present investigation explores the potential of pH sensitive cationic liposomes for its in vivo tumor targeted gene transfection in comparison to its marketed transfecting reagent Lipofectamine (R) 2000. The lipoplexes were prepared by varying the molar mass ratio of cationic pH-sensitive liposomes with respect to pDNA and were evaluated for optimum size, zeta potential and for complete gel retardation. Similarly, the stability of lipoplexes in the presence of DNase I and serum was evaluated by using gel retardation and heparin displacement assay. The in vitro hemocompatibility assessment of pDNA lipoplexes revealed < 8.5% of hemolysis which was lower than the hemolysis observed for Lipofectamine (R) lipoplexes (15.9%). The internalization and pH dependent uptake inhibition using ammonium chloride in MCF-7 cells revealed higher internalization and pH sensitive nature of the prepared pH-sensitive system. The pDNA lipoplexes displayed > 80% of cell viability along with 4.42, 5.18 and 5.00 fold higher transfection efficiency than Lipofectamine (R) lipoplexes in MCF-7, HeLa and HEK-293 cells respectively. Also the in vivo toxicity assessment exhibited no significant change in the levels of biomarkers and no histopathological deformations in case of pDNA lipoplexes treated animals in comparison to control group (PBS). Further, pDNA lipoplexes demonstrated similar to 1.3 fold higher tumor transfection over Lipofectamine (R) lipoplexes indicating superior in vivo gene deliverable capabilities. Thus, the developed pH sensitive lipoplexes promises to be a potential tumor targeting and safe delivery system than Lipofectamine (R) 2000.