Novel bioreducible poly(amido amine)s for highly efficient gene delivery.
A series of novel bioreducible poly(amido amine)s containing multiple disulfide linkages (SS-PAAs) were synthesized and evaluated as nonviral gene vectors. These linear SS-PAAs could be easily obtained by Michael-type polyaddition of various primary amines to the disulfide-containing cystamine bisacrylamide. The SS-PAA polymers are relatively stable in medium mimicking physiological conditions (pH 7.4, 150 mM PBS, 37 degrees C), but are rapidly degraded in the presence of 2.5 mM DTT, mimicking the intracellular reductive environment (pH 7.4, [R-SH] = 5 mM, 37 degrees C). The polymers efficiently condense DNA into nanoscaled (<200 nm) and positively charged (>+20 mV) polyplexes that are stable under neutral conditions but are rapidly destabilized in a reductive environment, as was revealed by both dynamic light scatting measurement and agarose gel assays. Moreover, most of the poly(amido amine)s possess buffer capacities in the pH range pH 7.4-5.1 that are even higher than polyethylenimine (pEI), a property that may favorably contribute to the endosomal escape of the polyplexes. Polyplexes of four of the seven SS-PAAs studied were able to transfect COS-7 cells in vitro with transfection efficiencies significantly higher than those of branched pEI, being one of the most effective polymeric gene carriers reported to date. Importantly, also in the presence of serum, a high level of gene expression could be observed when the incubation time was elongated from 1 h to 4 h. XTT assays showed that SS-PAAs and their polyplexes possess essentially no or only very low cytotoxicity at concentrations where the highest transfection activity is observed. The results indicate that bioreducible poly(amido amine)s have excellent properties for the development of highly potent and nontoxic polymeric gene carriers.
Lin
Chao
C
Department of Biomedical Chemistry and Department of Polymer Chemistry and Biomaterials, Institute for Biomedical Technology (BMTI), Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Zhong
Zhiyuan
Z
Lok
Martin C
MC
Jiang
Xulin
X
Hennink
Wim E
WE
Feijen
Jan
J
Engbersen
Johan F J
JF
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D015394:Molecular Structure; D008970:Molecular Weight; D010316:Particle Size; D011073:Polyamines / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D017186:Titrimetry; D014162:Transfection / Q000379:methods*
D004220:Disulfides; D011073:Polyamines; D004247:DNA