Linear polyethylenimine produced by partial acid hydrolysis of poly(2-ethyl-2-oxazoline) for DNA and siRNA delivery in vitro

Abstract

Polyethylenimines (PEIs) are the most efficient synthetic vectors for gene delivery available to date. With its high charge density and strong proton-buffering effect, PEI has an ability to condense DNA and small interfering RNA at physiologic pH. However, the polymer suffers from the disadvantage of high cellular toxicity. To reduce its cellular toxicity, we synthesized linear PEIs by partial hydrolysis of poly(2-ethyl-2-oxazoline). Three linear PEIs with different hydrolysis percentages (30%, 70%, and 96%, respectively) were produced as PEI30, PEI70, and PEI96. PEI30 and PEI96 cannot be considered as suitable transfection agents because of low transfection efficiency (PEI30) or high cellular toxicity (PEI96). PEI70 displayed very weak cell toxicity. The charge density of this polymer (PEI70) was strong enough to condense DNA and small interfering RNA at a physiologic pH of 7.4. Our results also show that PEI70 was highly efficient in DNA delivery and small interfering RNA-mediated knockdown of target genes. Thus, polymers such as PEI70 appear to be very promising vectors for gene delivery.

PEGylated Polyethylenimine Derivative-Mediated Local Delivery of the shSmad3 Inhibits Intimal Thickening after Vascular Injury

“…The formation of polymer/DNA complexes is a necessary step in gene delivery, which needs to protect the gene cargo from enzymatic degradation [42]. The migration of shSmad3 gene was completely retarded when the weight ratio (N/P ratio) was 5 or higher (Figure 2(b)), indicated that PEG-Et 1:1/shSmad3 complexes could be prepared at those N/P ratios.…”

“…Compared with PEI-Et and PEI 25 kDa, PEG-Et 1:1 exhibited significantly lower cytotoxicity in VSMCs (Figure 3(a)); as for the cytotoxicity of polymer/scrambled shRNA complexes (Figure 3(b)), PEG-Et 1:1/scrambled shRNA complexes also exhibited lower cytotoxicity than PEI-Et/scrambled shRNA and PEI 25 kDa/scrambled shRNA complexes. PEG modification could help reduce the number of PEI amino groups by coupling reaction to decrease the surface charge [42]. Therefore, lower cytotoxicity of PEG-Et 1:1 was probably attributed to the reduction of positive charge after PEG modification.…”