Cationic Polymer Gene Transfection Vectors

Gene therapy is a broad term that encompasses any strategy to treat a disease by introducing an exogenous gene into cells of an affected person. The safe and effective delivery of therapeutic genes remains a critical stumbling block in the field of gene therapy. Although viral vectors have been demonstrated high transfection efficiencies, safety risks, harder production and little gene-carrying capacity remain issues to be solved. Therefore, non-viral synthetic carriers, such as cationic polymers and lipids have been considered as potential alternative. One of the most successful and widely studied gene delivery polymers reported to date is polyethylenimine(PEI) because of its high density of cations. Due to its reatively high gene delivery efficiency and ready availability ,branched 25kDa PEI have become a benchmark to which other polymers, especially newly designed and synthesized materials, are often compared. However it is cytotoxic in many cell lines. Smaller PEI are usually non-cytotoxic but less efficiency. In the present study, to enhance the gene delivery efficiency and minimize cytotoxicity of PEL one hundred of polymers were prepared by non-cytotoxic smaller PEI( branched 800Da or 2000Da) reaction with different potentially biodegradable linkages. The efficiency of these polymers during in vitro delivering plasmid containing enhanced green fluorescent protein (EGFP) gene reporter were assessed in melanoma B16F10 cells. Among these polymers, two have the high transfection efficiency (GFP positive ratio >50%). Their transfection efficiency was investigated in other cell lines. Compared to commercially available 25-kDa PEI, the two polymers reported here could mediate more efficient expression of reporter gene than the 25-kDa PEI control, 10 and 8.5-fold more efficiency in B16F10 cells, 8.2 and 9.8-fold in 293T cells, 3.6 and 2.9-fold in 3T3 cells. The two polymers reported here mediate gene expression more efficiency than commercially available Lipofectimine2000 (Invitrogen Crop.) and PrimeFectimine (PrimGen Crop.) in 3T3 cells and the similar efficiency in B16F10 cells. In addition, cytotoxicity of the two polymers was measured in B16f10, 293T, 3T3 cell lines. The results indicate that the two polymers exhibited lower cytotoxicity than 25kDa PEI. All these results demonstrated that the two polymers can be applied as safe and efficiency gene delivery polymer in vitro.