(484a) Virus-Mimicking Nanoparticles with Polyamine/DNA Core and Acid-Degradable Polymeric Shell for Efficient Intracellular Gene Delivery

Gene therapy holds high promise for treating a number of diseases caused by genetic abnormalities. However, developing safe and efficient gene delivery vectors is still a major challenge. Viral vectors, which entered clinical trials first, are highly efficient but also at the same time offer significant drawbacks such as immunogenicity and innately limited cargo capacity. Nonviral vectors, though far less efficient than viral vectors, provide large cargo loading capacity, flexible modifications for versatile applications, and low immunogenicity. In this study, we mimicked a viral vector consisting of gene carrying capsid and fusogenic envelope, by creating a similar core-shell structure such that plasmid DNA is condensed by biologically available polyamines in the core and further shelled by acid-degradable polymers for efficient endosomal escape. Biologically available polyamines (e.g., protamine sulfate [PS] and spermine [SPM]) are known to complex DNA with low transfection efficiency attributed to poor intracellular processes. It was hypothesized that introducing acid-degradable polymeric shell to polyamine/DNA polyplexes by surface-initiated photopolymerization would result in efficient gene transfection via improved intracellular processes. The resulting nanoparticle structure of polyamine/DNA core and acid-degradable polymeric shell was confirmed by acid-hydrolysis of polymeric shell at pH 5.0, followed by core disassembly in the presence of a cytosolic reducer, heparan sulfate (HS). Gel electrophoresis and transmission electron microscopy (TEM) also evidenced the sequential acid-degradation of the polymeric shell and DNA/polyamine core disassembly, under endosomal and cytosolic conditions. In vitro transfection efficiency of the core-shell nanoparticles was significantly enhanced compared to their polyplex counterparts and even branched polyethylenimine (PEI, 25 kDa)/DNA polyplexes. Finally, virus-mimicking intracellular fate of the core-shell nanoparticles was observed by confocal laser scanning microscopy. In conclusion, equipping bio-available polyamine/DNA polyplexes with a stimuli-degradable polymeric shell enabled efficient and biocompatible gene delivery.