Effective Gene Delivery Using Stimulus-Responsive Catiomer Designed with Redox-Sensitive Disulfide and Acid-Labile Imine Linkers

Abstract

A dual stimulus-responsive mPEG-SS-PLL(15)-glutaraldehyde star (mPEG-SS-PLL(15)-star) catiomer is developed and biologically evaluated. The catiomer system combines redox-sensitive removal of an external PEG shell with acid-induced escape from the endosomal compartment. The design rationale for PEG shell removal is to augment intracellular uptake of mPEG-SS-PLL(15)-star/DNA complexes in the presence of tumor-relevant glutathione (GSH) concentration, while the acid-induced dissociation is to accelerate the release of genetic payload following successful internalization into targeted cells. Size alterations of complexes in the presence of 10 mM GSH suggest stimulus-induced shedding of external PEG layers under redox conditions that intracellularly present in the tumor microenvironment. Dynamic laser light scattering experiments under endosomal pH conditions show rapid destabilization of mPEG-SS-PLL(15)-star/DNA complexes that is followed by facilitating efficient release of encapsulated DNA, as demonstrated by agarose gel electrophoresis. Biological efficacy assessment using pEGFP-C1 plasmid DNA encoding green fluorescence protein and pGL-3 plasmid DNA encoding luciferase as reporter genes indicate comparable transfection efficiency of 293T cells of the catiomer with a conventional polyethyleneimine (bPEI-25k)-based gene delivery system. These experimental results show that mPEG-SS-PLL(15)-star represents a promising design for future nonviral gene delivery applications with high DNA binding ability, low cytotoxicity, and high transfection efficiency.

Polyethylene glycol–poly(ε-benzyloxycarbonyl-L-lysine)-conjugated VEGF siRNA for antiangiogenic gene therapy in hepatocellular carcinoma

“…This is a match with previous literature, where it has been reported that siVEGF with non-PEG-SS-PLL vectors had low toxicity at a concentration of 200 nM. 27 The novel biodegradable PEG-SS-PLL catiomer significantly improved transfection efficiency up to 96%, markedly higher than previous studies (81.3%). 2,39 The catiomer delivered siVEGF into tumor cells more efficiently, because aggregates formed due to reductive cleavage of the intermediate disulfide bonds and resulted in the shedding of the PEG layers.…”

“…The protocol used to assess the stability of the PEG-SS-PLL/siVEGF complex in response to GSH has been described elsewhere. 27 GSH was added to a diluted solution of PEG-SS-PLL/siVEGF complex containing 10% FBS to reach a final concentration of 10 mM GSH. The size change of the complex was monitored by dynamic light scattering.…”

“…It was found that the PEG-SS-PLL catiomer effectively delivered plasmid DNA into HeLa cells in vitro with negligible cytotoxicity. [26][27][28] However, there have been no studies regarding PEG-SS-PLL-mediated siVEGF delivery into cancer cells and the antitumor effect of siVEGF. 29 In this study, we aimed to investigate whether this novel biodegradable catiomer was capable of delivering siVEGF into cancer cells and had an antitumor effect in a xenograft mouse model, as in Scheme 1.…”

Cleavable PEGylation and Hydrophobic Histidylation of Polylysine for siRNA Delivery and Tumor Gene Therapy

“…The buffering capacity of the copolymers was measured by acid−base titration. 6 In brief, copolymers (6 mg) were dissolved in 150 mM NaCl (30 mL) and were adjusted to pH 10 with 0.1 M NaOH. The solutions were stepwise added 0.1 M HCl (5 μL each time), and the pH values measured by a microprocessor pH meter were recorded.…”

Disulfide-Bridged Cleavable PEGylation in Polymeric Nanomedicine for Controlled Therapeutic Delivery

“…We also carried out systematic studies on PEGylated PLL [98], and PEGylated PLL combined with hydrophilic poly(l-histidine) [30] or hydrophobic poly(Lhistidine-Bzl) [50] as gene vectors. The PLL structure was optimized to enhance the biological efficacy of cleavable PEGylation.…”