Cationic polyelectrolyte-mediated delivery of antisense morpholino oligonucleotides for exon-skipping in vitro and in mdx mice

Abstract

In this study, we investigated a series of cationic polyelectrolytes (PEs) with different size and composition for their potential to improve delivery of an antisense phosphorodiamidate morpholino oligomer (PMO) both in vitro and in vivo. The results showed that the poly(diallyldimethylammonium chloride) (PDDAC) polymer series, especially PE-3 and PE-4, improves the delivery efficiency of PMO, comparable with Endoporter-mediated PMO delivery in vitro. The enhanced PMO delivery and targeting to dystrophin exon 23 was further observed in mdx mice, up to fourfold with the PE-4, compared with PMO alone. The cytotoxicity of the PEs was lower than that of Endoporter and polyethylenimine 25,000 Da in vitro, and was not clearly detected in muscle in vivo under the tested concentrations. Together, these results demonstrate that optimization of PE molecular size, composition, and distribution of cationic charge are key factors to achieve enhanced PMO exon-skipping efficiency. The increased efficiency and lower toxicity show this PDDAC series to be capable gene/antisense oligonucleotide delivery-enhancing agents for treating muscular dystrophy and other diseases.

Keywords:

• cationic polyelectrolytes
• antisense delivery
• exon-skipping
• PMO
• muscular dystrophy

Acknowledgments

The authors would like to thank Drs David M Foureau and Fei Guo for their technical assistance with the flow cytometry and analysis, and Mrs Daisy M Ridings and Ben Wagner from the Electron Microscopy Core Laboratory for the negative staining and transmission electron micrographs. The authors also gratefully acknowledge the financial support provided by the Carolinas Muscular Dystrophy Research Endowment at the Carolinas HealthCare Foundation and Carolinas Medical Center, Charlotte, NC, USA.

Disclosure

The authors declare no conflicts of interest in this work.