Simple Modifications of Branched PEI Lead to Highly Efficient siRNA Carriers with Low Toxicity

Abstract

Polymer carriers like PEI which proved their efficiency in DNA delivery were found to be far less effective for the applications with siRNA. In the current study, we generated a number of nontoxic derivates of branched PEI through modification of amines by ethyl acrylate, acetylation of primary amines, or introduction of negatively charged propionic acid or succinic acid groups to the polymer structure. The resulting products showed high efficiency in siRNA-mediated knockdown of target gene. In particular, succinylation of branched PEI resulted in up to 10-fold lower polymer toxicity in comparison to unmodified PEI. Formulations of siRNA with succinylated PEI were able to induce remarkable knockdown (80% relative to untreated cells) of target luciferase gene at the lowest tested siRNA concentration of 50 nM in Neuro2ALuc cells. The polyplex stability assay revealed that the efficiency of formulations which are stable in physiological saline is independent of the affinity of siRNA to the polymer chain. The improved properties of modified PEI as siRNA carrier are largely a consequence of the lower polymer toxicity. In order to achieve significant knockdown of target gene, the PEI-based polymer has to be applied at higher concentrations, required most probably for sufficient accumulation and proton sponge effects in endosomes. Unmodified PEI is highly toxic at such polymer concentrations. In contrast, the far less toxic modified analogues can be applied in concentrations required for the knockdown of target genes without side effects.

Cholesterol improves the transfection efficiency of polyallylamine as a non-viral gene delivery vector

“…Zintchenko et al (2008) reported similar results for PEI modified with propionic acid or succinic acid. Thomas et al (2005) argue that transfection ability is reduced if polycation positive charge is highly reduced while in previous studies, Oskuee et al (2015b) concluded that polyplex transfection activity was not influenced by hydrophobic-modified PAA65 kDa.…”

Fatty acid–spermine conjugates as DNA carriers for nonviral in vivo gene delivery

“…Compared with physical methods, chemical systems have low efficiency and, in spite of their safety, they frequently show toxic properties because of the high concentrations of carriers that are needed to obtain significant gene expression. [5][6][7][8] Thus, highly efficient nonviral gene carriers are needed. For this purpose, DNA condensation is a recurrent requisite for this type of nonviral therapeutic approach.…”

“…For this purpose, DNA condensation is a recurrent requisite for this type of nonviral therapeutic approach. 5,[8][9][10][11][12] Bloomfield 13 has defined DNA condensation as the collapse of extended DNA chains into compact, orderly particles containing only one or a few molecules. Typically, this process results from a neutralization of the negative charges of the DNA phosphate groups with transition into the ordered phase that occurs when 90% of charges are neutralized.…”

A functional nanocarrier that copenetrates extracellular matrix and multiple layers of tumor cells for sequential and deep tumor autophagy inhibitor and chemotherapeutic delivery

“…52 In vitro, blank PSP/GNP displays a lower toxicity compare with PP/GNP, which could be due to the succinylation of bPEI that may significantly reduce the cytotoxicty of bPEI. 53 Even under a high concentration of 2000 mg/ml, cells treated with PSP@GNP could still survive above 80% after 48-h incubation (Fig. S13), which meant having little impact on our short-term in vitro and in vivo experiments.…”