title: Biodegradable poly(ester amine) based on glycerol dimethacrylate and polyethylenimine as a gene carrier.
abstract: BACKGROUND
  Polyethylenimine (PEI) vectors are widely used in gene delivery because of their high transfection efficiency owing to a unique proton sponge effect. An increase in molecular weight increases transfection efficiency, but simultaneously results in increased toxicity. Therefore, the design and synthesis of new degradable gene delivery carriers having high transfection efficiencies and reduced cytotoxicity are necessary.
  
  
  METHODS
  In the present study degradable poly(ester amines) (PEAs) based on glycerol dimethacrylate (GDM) and low molecular weight branched polyethylenimine (LMW-PEI) were synthesized in anhydrous methanol at 60 degrees C following Michael addition reaction. The transfection efficiencies of the synthesized PEA/DNA complexes were evaluated using three different cell lines (HeLa, HepG2 and 293T cells) in vitro.
  
  
  RESULTS
  PEAs with zeta potential in the range of 30-55 mV (at physiological pH) condensed plasmid DNA into nanosized particles (<150 nm) suitable for intracellular delivery. The PEAs degraded in a controlled fashion (t(1/2) of approximately 9-10 days). Compared with PEI 25K, the PEAs showed significantly lower cytotoxicity in three different cells. The PEAs demonstrated much higher transfection efficiency compared to conventional PEI 25K and Lipofectamine. The PEA synthesized using a 1 : 4 mole ratio of GDM to PEI [GDM/PEI-1.2 (1:4)] showed the highest transfection efficiency in HepG2 cells. Significantly higher pEGFP-N(2) reporter gene expression in 293T cells was achieved using these PEAs. The hyperosmotic effect of PEAs was demonstrated by the reduction in packed cell volume (PCV). The GDM/PEI-1.2 (1:4) showed comparable reduction in PCV with respect to glycerol in 293T cells. The effect of bafilomycin A(1) on transfection efficiency of PEAs on 293T cells indicated its endosomal buffering capacity.
  
  
  CONCLUSIONS
  We hypothesized that the higher transfection efficiency of PEAs was the synergistic effect arising from hyperosmotic glycerol and endosomal buffering capacity of PEAs resulting from the presence of a glycerol backbone and PEI amine groups, respectively.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea.
authors.forename: Rohidas B
authors.initials: RB
authors.lastname: Arote
authors.forename: Soon-Kyung
authors.initials: SK
authors.lastname: Hwang
authors.forename: Mi-Kyong
authors.initials: MK
authors.lastname: Yoo
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Jere
authors.forename: Hu-Lin
authors.initials: HL
authors.lastname: Jiang
authors.forename: You-Kyoung
authors.initials: YK
authors.lastname: Kim
authors.forename: Yun-Jai
authors.initials: YJ
authors.lastname: Choi
authors.forename: Jae-Woon
authors.initials: JW
authors.lastname: Nah
authors.forename: Myung-Haing
authors.initials: MH
authors.lastname: Cho
authors.forename: Chong-Su
authors.initials: CS
authors.lastname: Cho
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism; D018014:Gene Transfer Techniques; D005990:Glycerol / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008689:Methacrylates / Q000737:chemistry*; D018613:Microscopy, Confocal; D008970:Molecular Weight; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism; D011094:Polyethyleneimine / Q000737:chemistry*; D014162:Transfection
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D018942:Macrolides; D008689:Methacrylates; D011073:Polyamines; D011091:Polyesters; C516446:poly(caprolactone-block-ethyleneimine); C040929:bafilomycin A1; D011094:Polyethyleneimine; D004247:DNA; D005990:Glycerol