African Journal of Biotechnology

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The effect of pegylation on the transfection activity of two homologous cationic cholesteryl cytofectins

M Singh, J Borain, N Noor-Mahomed, M Ariatti


Polyethylene glycol is being used increasingly to improve circulation times and enhance bioavailability of therapeutic molecules and nano sized macromolecular assemblies. Here, two homologous cationic cholesteryl cytofectins 3β[N-(N’,N’-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and 3β[N- (N’,N’-dimethylaminopropane)-carbamoyl] cholesterol (Chol-T) with 2 and 3 carbon spacer elements, respectively, have been formulated into liposomes with near equimolar amounts of dioleoylphosphatidyl ethanolamine (DOPE) and 2 and 5% polyethylene glycol2000 (PEG2000). Pegylated liposomes (80 - 150 nm diameter) formed electrostatic complexes with plasmid DNA in the 1.5:1 – 2.5:1 range of liposome (positive): DNA (negative) charge ratio, which afforded protection to the DNA cargo against serum nuclease digestion. Plasmid pGL3-containing pegylated lipoplexes were only weakly cytotoxic in the human embryonic kidney cell line HEK 293. Gene transfer experiments in this cell line confirmed that the homologue with the 3 carbon spacer Chol-T, is associated with higher transgene activity, a trend which has been previously observed in unpegylated lipoplexes. Furthermore, only a 15% drop in transfection activity was recorded in increase of pegylation level from 2 to 5 mole percent.

Key words: Cationic cytofectin, gene transfer, polyethylene glycol, HEK 293.

AJOL African Journals Online