Polymer-peptide ternary systems as a tool to improve the properties of plasmid DNA vectors in gene delivery

Abstract

Polymer/peptide/plasmid DNA (pDNA) based ternary systems were developed by combining the great condensing ability of both polyethylenimine (PEI) and cell-penetrating peptides (RALA or TAT). This approach leads to the formation of lower sized vectors displaying positive charges and a high pDNA complexation ability, at low nitrogen to phosphate groups ratio. Compared to the binary polymer/pDNA or peptide/pDNA complexes, higher amounts of PEI or peptides are required to condense the pDNA and conceive formulations with similar properties. Moreover, the polymer/peptide/pDNA nanoparticles are able of pDNA release when the intracellular environment was mimicked. Taking advantage of the favourable characteristics, for cellular uptake and gene delivery exhibited by ternary systems, in vitro studies were performed on cancer cells. The obtained results revealed the capacity of the developed carriers for cell internalization and pDNA localization within or in close proximity to the nucleus. In line with this, gene expression was detected and the produced protein levels were quantified, and showed to be significantly higher when compared to binary pDNA based carriers. The PEI/peptide/pDNA ternary systems offer remarkable potential for the conceptual design and formation of advanced bio-functional vectors towards the most demanding biomedical applications.