| RESEARCH PAPER |
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| Year : 2011 | Volume
: 73
| Issue : 4 | Page : 381-386 |
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Cytofectin amine head group modification and degree of liposome pegylation: Factors influencing gene transfer
Aliscia Daniels, Naeema Noor-Mahomed, Moganavelli Singh, M Ariatti
Non-Viral Gene Delivery Laboratory, Department of Biochemistry, Westville Campus, University of KwaZulu-Natal, P Bag X54001, Durban 4000, South Africa
Correspondence Address:
M Ariatti
Non-Viral Gene Delivery Laboratory, Department of Biochemistry, Westville Campus, University of KwaZulu-Natal, P Bag X54001, Durban 4000
South Africa
DOI: 10.4103/0250-474X.95613
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The effectiveness of liposome-mediated gene transfer methods hinges, in part, on the nature of the interaction between the DNA cargo and the liposomes. Here we have examined the effect of quaternization of the cytofectin cationic head group on this interaction and the effect of concentration of the biocompatible, protective polymer polyethylene glycol 2000 (PEG 2000 ) on transfection activity. Thus 3β[N-(N',N'-dimethylaminopropane)-carbamoyl] cholesterol (Chol-T) and 3β[N-(N',N',N'-trimethylammonium propane)-carbamoyl] cholesterol iodide (Chol-Q), differing only in the degree of head group methylation, have been formulated into liposomes with polyethylene glycol 2000 -distearoylphosphatidyl ethanolamine (DSPE PEG 2000 ) and the neutral co-lipid dioleoylphosphatidylethanolamine (DOPE). Their DNA-binding characteristics have been determined and the gene transfer capabilities of resulting lipoplexes have been examined in HEK 293 human embryonic kidney cells. Quaternary ammonium Chol-Q liposomes were found to bind DNA more avidly than their tertiary amine Chol-T counterparts. The inclusion of PEG 2000 in liposome formulations resulted in an increase in the optimal liposome-DNA binding ratio. Chol-T liposomes promoted transgene activity levels 5 times greater than those obtained with Chol-Q lipoplexes. Furthermore, a drop in transfection activity of only 17% was noted on increase of liposome pegylation from 2 to 5 mole percent. The study's findings suggest that strong association between cationic liposomes and DNA may lead to reduced levels of transfection activity as a result of poor release of nucleic acid after cellular uptake. |
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