Speaker at Global Conference on Pharmaceutics and Drug Delivery Systems 2018 - Ali Dehshahri
Shiraz University of Medical Sciences, Iran (Islamic Republic of)
Title : Polyethylenimine-based nanoparticles decorated with small molecules mimicking RGD peptide for targeted plasmid DNA delivery


Targeted delivery of polymer-based nanoparticles has been considered as an efficient approach to transfer genetic materials into cells. Considering the over expression of integrin αVβ3 receptor on tumor cells and the presence of the binding site for tetraiodothyroacetic acid (tetrac) and L-thyroxine on integrin receptor, we hypothesized that the conjugation of these small molecules to polyethylenimine (PEI) at different conjugation degrees might be an effective strategy for pDNA delivery into the cells over-expressing integrins on their surfaces. In order to test the hypothesis, the 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, apoptotic effects and plasmid protection against DNase degradation. The results demonstrated that the majority of the 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 85-200 nm. The highest level of IL-12 gene expression was achieved by terac-conjugated PEIs at where they could increase the level of gene expression up to 4 fold in the cell lines over-expressing integrin αVβ3 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 αvβ3 receptor. On the other hand, tetrac and L-thyroxine conjugation of PEI significantly reduced the polymer-induced apoptotic effects. Also, the results of in vivo imaging of the polyplexes revealed that 99mTc-labeled PEI/pDNA complexes accumulated in kidney and bladder 4 h post injection. The results obtained in this investigation suggest the potential of tetrac and L-thyroxine as small molecules mimicking the binding properties of integrin binding peptides (e.g., RGD) for targeted gene delivery.

Audience take away:
• The audience will learn the importance of small molecules mimicking RGD properties for integrin targeting.
• These small molecules can be conjugated on various delivery systems using simple conjugation strategies and might be used for targeted gene and drug delivery.
• Since there are some limitations for the application of peptide or proteins as targeting ligands, small molecules with targeting properties might be considered as alternative ligands. 


Ali Dehshahri is currently associate professor of pharmaceutical biotechnology at Shiraz University of Medical Science, Iran. He earned his Ph.D. at Mashhad University of Medical Sciences, Iran, in 2009, working with Prof. Mohammad Ramezani. In his thesis, he investigated the role of polymer amine content on its efficiency for gene delivery. As a distinguished Ph.D student, he was awarded a short-term research grant from the Iranian Ministry of Health to pursue his investigation at LMU, Munich, Germany under the supervision of Prof. Ernst Wagner on polymeric nanoparticles for siRNA delivery. In 2014, Dr. Dehshahri accepted an Associate Professor position at Shiraz University of Medical Sciences, where he has been since that time.