Agmatine-grafted bioreducible poly(L-lysine) for gene delivery with low cytotoxicity and high efficiency
Bioreducible cationic polymers have gained considerable attention in gene delivery due to low cytotoxicity and high efficiency. In the present work, we reported a cationic polymer poly(disulfide-L-lysine)-g-agmatine (denoted as SSL-AG) and evaluated its ability to transfer pEGFP-ZNF580 plasmid (pZNF580) into human umbilical vein endothelial cells (HUVECs). This SSL-AG polymeric carrier efficiently condensed pZNF580 into positively charged particles (< 200 nm) through electrostatic interaction. This carrier also exhibited excellent buffering capacity in the physiological environment, good pDNA protection against enzymatic degradation and rapid pDNA release in high reducing environment mainly because of the responsive cleavage of disulfide bonds in the polymer backbone. The hemolysis assay and in vitro cytotoxicity assay suggested that SSL-AG carrier and corresponding gene complexes possessed both good hemocompatibility and great cell viability in HUVECs. The SSL-AG/Cy5-oligonucleotide group showed 3.6-times improved cellular uptake than poly(L-lysine)/Cy5-oligonucleotide), and possessed even higher mean fluorescence intensity value than PEI25kDa/Cy5-oligonucleotide group. Further, the intracellular trafficking results demonstrated that the SSL-AG/Cy5-oligonucleotide complexes exhibited high nucleus co-localization rate(CLR) value (36.0 ± 2.8%, 3.4 times of poly (L-lysine)/Cy5-oligonucleotide group, 1.6 times of poly(disulfide-L-lysine)-g-butylenediamine/Cy5-oligonucleotide group) at 24 h, while the endo/lysosomal CLR value was relatively low. It suggested that the SSL-AG successfully delivered plasmid into HUVECs with high cellular uptake, rapid endosomal escape and efficient nuclear accumulation owing to the structural advantages of bioreducible and agmatine groups. In vitro transfection assay also verified the enhanced transfection efficiency in SSL-AG/pZNF580 group. Furthermore, the results of CCK-8, cell migration and in vitro/vivo angiogenesis assays revealed that pZNF580 delivered by SSL-AG could effectively enhance the proliferation, migration and vascularization of HUVECs. In a word, the SSL-AG polymer has great potential as a safe and efficient gene carrier for gene therapy.
- This article is part of the themed collection: Journal of Materials Chemistry B HOT Papers