Ternary complexes comprising polyphosphoramidate gene carriers with different types of charge groups improve transfection efficiency.
To understand the influence of charge groups on transfection mediated by polymer complexes, we have synthesized a series of biodegradable and cationic polyphosphoramidates (PPAs) with an identical backbone but different side chains. Our previous study showed that PPA with a spermidine side chain (PPA-SP) showed high transfection efficiency in culture, whereas PPAs with secondary, tertiary, and quaternary amino groups were significantly less efficient. To investigate whether the coexistence of 1 degrees amino charge groups with 3 degrees and 2 degrees amino charge groups in the DNA/polymer complexes would enhance their transfection efficiency, we evaluated a ternary complex system containing DNA and PPAs with 1 degrees amino groups (PPA-SP) and 3 degrees amino groups (PPA-DMA) and a quaternary complex system containing DNA and PPAs with 1 degrees and 2 degrees and 3 degrees amino groups (PPA-EA/PPA-MEA/PPA-DMA), respectively. Ternary complexes mediated 20 and 160 times higher transfection efficiency in COS-7 cells than complexes of DNA with PPA-SP or PPA-DMA alone, respectively. Similarly, quaternary complexes exhibited 8-fold higher transfection efficiency than PPA-EA/DNA complexes. The mechanism of enhancement in transfection efficiency by the mixture carriers appears to be unrelated to the particle size, zeta potential, or DNA uptake. The titration characterization and the transfection experiments using a proton pump inhibitor suggest that the enhancement effect is unlikely due to the slightly improved buffering capacity of the mixture over PPA-SP. This approach represents a simple strategy of developing polymeric gene carriers and understanding the mechanisms of polymer-mediated gene transfer.
Zhang
Peng-Chi
PC
Tissue and Therapeutic Engineering Laboratory, Johns Hopkins Singapore, Singapore 117597, Singapore.
Wang
Jun
J
Leong
Kam W
KW
Mao
Hai-Quan
HQ
D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D000818:Animals; D019556:COS Cells / Q000187:drug effects; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D000882:Haplorhini; D006367:HeLa Cells / Q000187:drug effects; D006801:Humans; D010316:Particle Size; D010756:Phosphoric Acids / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship
D000577:Amides; D010756:Phosphoric Acids; D011108:Polymers; D004247:DNA; C011067:phosphoramidic acid