title: Poly(ethylene oxide) grafted with short polyethylenimine gives DNA polyplexes with superior colloidal stability, low cytotoxicity, and potent in vitro gene transfection under serum conditions.
abstract: Poly(ethylene oxide) grafted with 1.8 kDa branched polyethylenimine (PEO-g-PEI) copolymers with varying compositions, that is, PEO(13k)-g-10PEI, PEO(24k)-g-10PEI, and PEO(13k)-g-22PEI, were prepared and investigated for in vitro nonviral gene transfer. Gel electrophoresis assays showed that PEO(13k)-g-10PEI, PEO(24k)-g-10PEI, and PEO(13k)-g-22PEI could completely inhibit DNA migration at an N/P ratio of 4/1, 4/1, and 3/1, respectively. Dynamic light scattering (DLS) and zeta potential measurements revealed that all three graft copolymers were able to effectively condense DNA into small-sized (80-245 nm) particles with moderate positive surface charges (+7.2 ∼ +24.1 mV) at N/P ratios ranging from 5/1 to 40/1. The polyplex sizes and zeta-potentials intimately depended on PEO molecular weights and PEI graft densities. Notably, unlike 25 kDa PEI control, PEO-g-PEI polyplexes were stable against aggregation under physiological salt as well as 20% serum conditions due to the shielding effect of PEO. MTT assays in 293T cells demonstrated that PEO-g-PEI polyplexes had decreased cytotoxicity with increasing PEO molecular weights and decreasing PEI graft densities, wherein low cytotoxicities (cell viability >80%) were observed for polyplexes of PEO(13k)-g-22PEI, PEO(13k)-g-10PEI, and PEO(24k)-g-10PEI up to an N/P ratio of 20/1, 30/1, and 40/1, respectively. Interestingly, in vitro transfection results showed that PEO(13k)-g-10PEI polyplexes have the best transfection activity. For example, PEO(13k)-g-10PEI polyplexes formed at an N/P ratio of 20/1, which were essentially nontoxic (100% cell viability), displayed over 3- and 4-fold higher transfection efficiencies in 293T cells than 25 kDa PEI standard under serum-free and 10% serum conditions, respectively. Confocal laser scanning microscopy (CLSM) studies using Cy5-labeled DNA confirmed that these PEO-g-PEI copolymers could efficiently deliver DNA into the perinuclei region as well as into nuclei of 293T cells at an N/P ratio of 20/1 following 4 h transfection under 10% serum conditions. PEO-g-PEI polyplexes with superior colloidal stability, low cytotoxicity, and efficient transfection under serum conditions are highly promising for safe and efficient in vitro as well as in vivo gene transfection applications.
authors.affiliation: Biomedical Polymers Laboratory and Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering, and Materials Science, Soochow University , Suzhou, 215123, People's Republic of China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zheng
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhong
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Fenghua
authors.initials: F
authors.lastname: Meng
authors.forename: Rui
authors.initials: R
authors.lastname: Peng
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Zhong
mesh_terms: D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D003102:Colloids / Q000737:chemistry*; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000008:administration & dosage; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects; D008970:Molecular Weight; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000494:pharmacology; D011094:Polyethyleneimine / Q000737:chemistry* / Q000494:pharmacology; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology; D044967:Serum / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology; D014162:Transfection
chemical_list: D003102:Colloids; D011108:Polymers; D013501:Surface-Active Agents; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D004247:DNA