Abstract:

Nonviral gene delivery systems are considered to be a safe alternative to the viral system used in gene therapy. Although polyethylenimine (PEI) is among the most promising gene-carrier candidates for efficient nonviral gene delivery, safety concerns regarding its toxicity remain challenging. The aim of this study was to evaluate the less considered aspects of toxicity including genotoxicity effects of branched PEI with different molecular weights (1800 Da, 25 kDa, 750 kDa). Neuro2A mammalian cells were cultured in DMEM with 10% FBS and exposed to PEI/DNA complexes at different polymer/DNA ratios (known as the C/P ratio). To evaluate metabolic activities and genotoxicity, the treated cells were subjected to MTT and comet assays, respectively. Intracellular reactive oxygen species were also determined by using the fluorescent dye dichlorofluorescin diacetate. Concentration with relation to toxicity, genotoxicity, and ROS production was observed in Neuro2A cells treated with PEI/DNA nanoparticles. The difference among toxicities induced by different molecular weights of PEI at higher C/P ratios was significant, whereas no significant toxicity effect was induced by PEI at C/P ratios of 1 and lower. We found concentration-dependent genotoxicity and a direct correlation between nanoparticle concentrations and DNA damage, which cannot be ignored and should be considered for the design of new generations of PEI derivatives with enhanced delivery properties and reduced toxicity.

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