A low-toxic and efficient gene vector: carboxymethyl dextran-graft-polyethylenimine.

In this study, the low molecular weight branched polyethylenimine (PEI) (800 Da PEI) was grafted to the biodegradable and biocompatible carboxymethyl dextran (CMD) to obtain CMD-g-PEI, and the plasmid DNA was complexed with CMD-g-PEI polycation to form the polyion complex. The acid-base titration profile showed that the CMD-g-PEI had endosomal disruption capacity, and the agarose gel electrophoresis suggested that the CMD-g-PEI could condense DNA efficiently. The transfection efficiency of CMD-g-PEI/DNA complexes was measured by luciferase and green fluorescent protein assay in HEK293 cells. The results revealed that the transfection efficiency of CMD-g-PEI at the N/P ratios over 30-70 was higher than or comparable to that of the 25 kDa PEI at optimal ratio (N/P = 10). The cytotoxicity of CMD-g-PEI as well as 25 kDa PEI was evaluated in NIH3T3 and HEK293 cells, respectively, and it was also found that the cytotoxicity of CMD-g-PEI was much lower than that of 25 kDa PEI. The resulted CMD-g-PEI with high transfection efficiency and low cytotoxicity have promising applications when used as gene vector.