Regulation of in vitro gene expression using antisense oligonucleotides or antisense expression plasmids transfected using starburst PAMAM dendrimers

TLDR

Starburst PAMAM dendrimers are branched polymers with high surface charge. The study examined PAMAM dendrimers as delivery vehicles for antisense oligonucleotides and plasmids to modulate gene expression. Dendrimers bind nucleic acids electrostatically, enabling DNA‑dendrimer complexes to deliver antisense oligonucleotides and plasmids into cultured cells, including luciferase‑expressing lines generated by dendrimer transfection. Dendrimer‑mediated delivery of antisense oligonucleotides or plasmids dose‑dependently reduced luciferase activity by 25–50%, extended oligonucleotide stability, was non‑cytotoxic, and demonstrated effective specific gene suppression.

Abstract

Starburst polyamidoamine (PAMAM) dendrimers are a new type of synthetic polymer characterized by a branched spherical shape and a high density surface charge. We have investigated the ability of these dendrimers to function as an effective delivery system for antisense oligonucleotides and 'antisense expression plasmids' for the targeted modulation of gene expression. Dendrimers bind to various forms of nucleic acids on the basis of electrostatic interactions, and the ability of DNA-dendrimer complexes to transfer oligonucleotides and plasmid DNA to mediate antisense inhibition was assessed in an in vitro cell culture system. Cell lines that permanently express luciferase gene were developed using dendrimer mediated transfection. Transfections of antisense oligonucleotides or antisense cDNA plasmids into these cell lines using dendrimers resulted in a specific and dose dependent inhibition of luciferase expression. This inhibition caused ∼25–50% reduction of baseline luciferase activity. Binding of the phosphodiester oligonucleotides to dendrimers also extended their intracellular survival. While dendrimers were not cytotoxic at the concentrations effective for DNA transfer, some non-specific suppression of luciferase expression was observed. Our results indicate that Starburst dendrimers can be effective carriers for the introduction of regulatory nucleic acids and facilitate the suppression of the specific gene expression.