Tetraiodothyroacetic acid-conjugated polyethylenimine for integrin receptor mediated delivery of the plasmid encoding IL-12 gene

Abstract

Targeted delivery by polymer-based nanoparticles has been considered as an efficient approach to transfer genetic materials into cells. Considering the over expression of integrin αβ receptor on tumor cells and the presence of the binding site for tetraiodothyroacetic acid (tetrac) on integrin receptor, we hypothesized that the conjugation of tetrac to polyethylenimine (PEI) might be an effective strategy for pDNA delivery into the cells over-expressing integrins on their surfaces. In order to test the hypothesis, tetrac conjugated PEI/plasmid DNA complexes were prepared and their ability in the delivery of plasmid encoding IL-12 gene was investigated. Moreover, the conjugates were characterized with respect to plasmid DNA condensation ability, particle size and zeta potential as well as cell-induced toxicity and plasmid protection against DNase degradation. The results demonstrated that tetrac conjugated derivatives of PEI were able to condense the plasmid and protect it against enzyme degradation. The results of dynamic light scattering (DLS) and atomic force microscopy (AFM) revealed that the formed nanoparticles were in the size range of 85-125nm. The highest level of IL-12 gene expression was achieved by terac-conjugated PEIs at the carrier to plasmid ratio of 8 where they could increase the level of gene expression up to 4 fold in the cell lines over-expressing integrin αβ receptor whereas no increase in the level of IL-12 expression in the cell lines lacking integrin receptors was observed. Also, the results of the competitive inhibition of the receptors demonstrated the specificity of transfection for the cells over expressing αβ receptor. On the other hand, tetrac conjugation of PEI significantly reduced the polymer-induced apoptotic effects. The results obtained in this investigation suggest the potential of tetrac as a small molecule mimicking the binding properties of integrin binding peptides (e.g., RGD) for targeted gene delivery.

Targeted double domain nanoplex based on galactosylated polyethylenimine enhanced the delivery of IL‐12 plasmid

“…This slight increase in the particle size of the polyplexes might be associated with the introduction of larger molecules of lactose onto the targeting domain, which led to the formation of larger complexes. 40,42 However, this increase was not statistically significant. The particle size of the galactosylated derivatives plays a crucial role in their efficiency for gene delivery.…”

Double domain polyethylenimine-based nanoparticles for integrin receptor mediated delivery of plasmid DNA

“…Considering the deadly adverse reactions associated with the systemic administration of recombinant IL-12 protein in human body, researchers are seeking for alternative strategies including the transfer of IL-12 plasmid into the target tissue or organ. Since the elevated levels of IFN-γ has been considered as the major factor resulting in the systemic toxicity of IL-12, the production of the therapeutic protein inside the tumor site may reduce its systemic toxicity 6 – 9 . However, the successful transfer of such nucleic acid materials into the target cells has remained unfulfilled due to the lack of efficient, targeted, non-toxic and cost effective delivery systems 10 , 11 .…”

“…Therefore, the conjugation of targeting ligands via the amines on the surface of PEI has been proposed to direct the PEI/nucleic acid complexes into a specific site of action. These conjugation strategies may also reduce the cell-induced toxicity of PEI due the reduction of significant positive charge density on the polymer surface which is responsible for the induction of toxic effects 9 , 14 – 16 .…”

Preparation, characterization, and transfection efficiency of low molecular weight polyethylenimine-based nanoparticles for delivery of the plasmid encoding CD200 gene

“…These findings were in good agreement with previous studies in which the conjugation of alkyl moieties on PEI structure led to the formation of larger nanoparticles. 13,17,19,22,24,25,42 These substituted groups alter the surface interaction between the polymer and plasmid. As LMW PEI was coupled to the PEI-SUC structure, the primary amine density and consequently the net positive charge increased, which led to the formation of complexes with smaller size (128 nm).…”