title: Polyplexes of polyethylenimine and per-N-methylated polyethylenimine-cytotoxicity and transfection efficiency.
abstract: For non-viral gene delivery, the carriers for DNA transfer into cells must be vastly improved. The branched cationic polymer polyethylenimine has been described as an efficient gene carrier. However, polyethylenimine was demonstrated to mediate substantial cytotoxicity. Therefore, this study is aimed at investigating per-N-methylated polyethylenimine, which is thought to have a much lower cytotoxicity due to its lower charge density. Results from a gel retardation assay and laser light scattering indicated that per-N-methylated polyethylenimine condenses DNA into small and compact nanoparticles with a mean diameter <150 nm. Furthermore, polyplexes of polyethylenimine and per-N-methylated polyethylenimine with DNA had a positive zeta potential and the polymers protected DNA from nuclease-mediated digestion. The transfection efficiency of polyethylenimine and per-N-methylated polyethylenimine was tested in CHO-K1 cells. Using green fluorescent protein as reporter gene and flow cytometry analysis, we demonstrated that per-N-methylated polyethylenimine has a lower cytotoxicity, but also a significantly lower transfection efficiency. Using propidium iodide staining, we could additionally distinguish between viable and dead cells. At NP > or = 12, per-N-methylated polyethylenimine showed a much higher cell viability and the ratio of viable and transfected cells to dead and transfected cells was about 1.5 to 1.7 fold higher than for polyethylenimine. The results of cell viability from flow cytometry analysis were confirmed by the MTS assay. Using luciferase reporter gene for transfection experiments, the gene expression of per-N-methylated polyethylenimine was lower at NP 6, 12 and 18 as compared to polyethylenimine, but at NP 24 it yielded similar levels.
authors.affiliation: Department of Pharmaceutical Technology, University of Regensburg, Universitaetsstrasse 31, 93040 Regensburg, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Breunig
authors.forename: Uta
authors.initials: U
authors.lastname: Lungwitz
authors.forename: Juergen
authors.initials: J
authors.lastname: Klar
authors.forename: Armin
authors.initials: A
authors.lastname: Kurtz
authors.forename: Torsten
authors.initials: T
authors.lastname: Blunk
authors.forename: Achim
authors.initials: A
authors.lastname: Goepferich
mesh_terms: D000818:Animals; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000009:adverse effects / Q000737:chemistry; D006224:Cricetinae; D003412:Cricetulus; D004337:Drug Carriers / Q000009:adverse effects / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods*; D018014:Gene Transfer Techniques; D008422:Materials Testing; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D010957:Plasmids / Q000008:administration & dosage* / Q000235:genetics*; D011094:Polyethyleneimine / Q000009:adverse effects* / Q000737:chemistry*; D014162:Transfection / Q000379:methods*
chemical_list: D020099:Coated Materials, Biocompatible; D004337:Drug Carriers; D011094:Polyethyleneimine