The lower-generation polypropylenimine dendrimers are effective gene-transfer agents.
OBJECTIVE
To evaluate polypropylenimine dendrimers (generations 1-5: DAB 4, DAB 8, DAB 16, DAB 32, and DAB 64) as gene delivery systems.


METHODS
DNA binding was evaluated by measuring the reduced fluorescence of ethidium bromide, and molecular modelling of dendrimer-DNA complexes also was performed. Cell cytotoxicity was evaluated against the A431 cell line using the MTT assay. In vitro transfection was evaluated against the A431 cell line using the beta-galactosidase reporter gene and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methylsulphate (DOTAP) served as a positive control.


RESULTS
Molecular modeling and experimental data revealed that DNA binding increased with dendrimer generation. Cell cytotoxicity was largely generation dependent, and cytotoxicity followed the trend DAB 64 > DAB 32 > DAB 16 > DOTAP > DAB 4 > DAB 8, whereas transfection efficacy followed the trend DAB 8 = DOTAP = DAB 16 > DAB 4 > DAB 32 = DAB 64.


CONCLUSIONS
The generation 2 polypropylenimine dendrimer combines a sufficient level of DNA binding with a low level of cell cytoxicity to give it optimum in vitro gene transfer activity.
Department of Pharmaceutical Sciences, University of Strathclyde, Glasgow, Scotland.
Bernd H
BH
Zinselmeyer
Simon P
SP
Mackay
Andreas G
AG
Schatzlein
Ijeoma F
IF
Uchegbu
D004247:DNA / Q000008:administration & dosage / Q000235:genetics; D016503:Drug Delivery Systems / Q000379:methods; D004926:Escherichia coli; D018014:Gene Transfer Techniques; D006801:Humans; D007097:Imines / Q000008:administration & dosage* / Q000737:chemistry / Q000633:toxicity; D008958:Models, Molecular; D011126:Polypropylenes / Q000008:administration & dosage* / Q000737:chemistry / Q000633:toxicity; D014407:Tumor Cells, Cultured
D007097:Imines; D011126:Polypropylenes; D004247:DNA