Targeted Decationized Polyplexes for siRNA Delivery

Abstract

The applicability of small interfering RNA (siRNA) in future therapies depends on the availability of safe and efficient carrier systems. Ideally, siRNA delivery requires a system that is stable in the circulation but upon specific uptake into target cells can rapidly release its cargo into the cytoplasm. Previously, we evaluated a novel generation of carrier systems ("decationized" polyplexes) for DNA delivery, and it was shown that folate targeted decationized polyplexes had an excellent safety profile and showed intracellular triggered release upon cell specific uptake. Targeted decationized polyplexes consist of a core of disulfide cross-linked poly(hydroxypropyl methacrylamide) (pHPMA) stably entrapping nucleic acids and a shell of poly(ethylene glycol) (PEG) decorated with folate molecules. In the present study, the applicability of folate targeted decationized polyplexes for siRNA delivery was investigated. This required optimization of the carrier system particularly regarding the cross-linking density of the core of the polyplexes. Stable and nanosized siRNA decationized polyplexes were successfully prepared by optimizing the cross-link density of their core. Upon incubation in human plasma, a significant portion of siRNA remained entrapped in the decationized polyplexes as determined by fluorescence correlation spectroscopy (FCS). When tested in a folate receptor overexpressing cell line stably expressing luciferase, Skov3-luc, sequence specific gene silencing was observed. As expected, neither interference on the intrinsic luciferase expression nor on the cell metabolic activity (determined by XTT) was induced by the free-polymer or the siRNA polyplexes. In conclusion, targeted decationized polyplexes are safe and stable carriers that interact with the targeted cells and rapidly disassemble upon cell entry making them promising siRNA delivery systems.

Hydrolytic charge‐reversal of PEGylated polyplexes enhances intracellular un‐packaging and activity of siRNA

“…The level of knockdown achieved in vitro does not reach that of some of the most optimized transfection reagents, but the performance is comparable to other PEGylated or decationized delivery systems. 43,44 Overall, these data suggest that incorporation of mechanisms for un-packaging is a feasible route to improving the bioactivity of PEGylated polyplex delivery systems which notoriously are limited in their in vitro transfection potency relative to research-grade reagents that are optimized for in vitro use only.…”

Decationized polyplexes for gene delivery

“…The flexibility of these systems allows tuning of the structural design to adapt to different nucleic acids. For example, recently decationized polyplexes have been successfully used for siRNA applications [24], making RNA delivery an important area for future research. Furthermore, the ability of targeted decationized polyplexes to specifically interact with the target cells allows their potential use for a wide range of biomedical and pharmaceutical applications.…”

Monitoring drug nanocarriers in human blood by near-infrared fluorescence correlation spectroscopy

“…Due to its very high sensitivity and selectivity 13 the FCS technique has found numerous applications in fields ranging from cell biology 14,15 to polymer, colloid, and interface science 16–20 . FCS is perfectly suited for studying the formation of NCs 21,22 , their drug loading 23,24 , stability 25–27 , interactions with plasma proteins 28–32 and triggered release 33,34 . However, FCS has so far never been adapted to in situ blood measurements.…”