In vitro and in vivo effects of polyethylene glycol (PEG)-modified lipid in DOTAP/cholesterol-mediated gene transfection.
BACKGROUND
DOTAP/cholesterol-based lipoplexes are successfully used for delivery of plasmid DNA in vivo especially to the lungs, although low systemic stability and circulation have been reported. To achieve the aim of discovering the best method for systemic delivery of DNA to disseminated tumors we evaluated the potential of formulating DOTAP/cholesterol lipoplexes with a polyethylene glycol (PEG)-modified lipid, giving the benefit of the shielding and stabilizing properties of PEG in the bloodstream.


METHODS
A direct comparison of properties in vitro and in vivo of 4 different DOTAP/cholesterol-based lipoplexes containing 0%, 2%, 4%, and 10% PEG was performed using reporter gene activity and radioactive tracer lipid markers to monitor biodistribution.


RESULTS
We found that 10% PEGylation of lipoplexes caused reduced retention in lung and heart tissues of nude mice compared to nonPEGylated lipoplexes, however no significant delivery to xenograft flank tumors was observed. Although PEGylated and nonPEGylated lipoplexes were delivered to cells the ability to mediate successful transfection is hampered upon PEGylation, presumably due to a changed uptake mechanism and intracellular processing.


CONCLUSIONS
The eminent in vivo transfection potency of DOTAP/cholesterol-based lipoplexes is well established for expression in lung tumors, but it is unsuitable for expression in non first pass organs such as xenograft flank tumors in mice even after addition of a PEG-lipid in the formulation.
Department of Radiation Biology, Finsen Center, University Hospital, Copenhagen, Denmark.
Torben
T
Gjetting
Nicolai Skovbjerg
NS
Arildsen
Camilla Laulund
CL
Christensen
Thomas Tuxen
TT
Poulsen
Jack A
JA
Roth
Vagn Neerup
VN
Handlos
Hans Skovgaard
HS
Poulsen
D000818:Animals; D018288:Carcinoma, Small Cell / Q000235:genetics / Q000628:therapy; D045744:Cell Line, Tumor; D002784:Cholesterol; D016503:Drug Delivery Systems; D005229:Fatty Acids, Monounsaturated; D015870:Gene Expression; D017930:Genes, Reporter; D015316:Genetic Therapy; D006801:Humans; D066298:In Vitro Techniques; D008081:Liposomes; D008175:Lung Neoplasms / Q000235:genetics / Q000628:therapy; D008297:Male; D051379:Mice; D008819:Mice, Nude; D050997:Nanomedicine; D011092:Polyethylene Glycols; D000644:Quaternary Ammonium Compounds; D014162:Transfection; D014183:Transplantation, Heterologous
D005229:Fatty Acids, Monounsaturated; D008081:Liposomes; D000644:Quaternary Ammonium Compounds; D011092:Polyethylene Glycols; D002784:Cholesterol; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane