Prolonged gene silencing by combining siRNA nanogels and photochemical internalization

Abstract

Small interfering RNAs (siRNAs) show potential for the treatment of a wide variety of pathologies with a known genetic origin through sequence-specific gene silencing. However, siRNAs do not have favorable drug-like properties and need to be packaged into nanoscopic carriers that are designed to guide the siRNA to the cytoplasm of the target cell. In this report biodegradable cationic dextran nanogels are used to deliver siRNA across the intracellular barriers. For the majority of non-viral siRNA carriers studied so far, endosomal confinement is identified as the most prominent hurdle, limiting the full gene silencing potential. Thus, there is a major interest in methods that are able to enhance endosomal escape of siRNA to improve its intracellular bioavailability. Photochemical internalization (PCI) is a method that employs amphiphilic photosensitizers to destabilize endosomal vesicles. We show that applying PCI at a later time-point post-transfection significantly prolonged the knockdown of the target protein only in case the siRNA was carried by nanogels and not when a liposomal carrier was used. Combining siRNA nanogels and PCI creates new possibilities to prolong gene silencing by using intracellular vesicles as depots for siRNA and applying PCI at the time when maintaining the RNAi effect becomes critical. Graphical abstractCombining siRNA nanogels and photochemical internalization (PCI) creates new possibilities to prolong gene silencing by using intracellular vesicles as depots and applying PCI at the time when maintaining the RNAi effect becomes critical.

Polymers in Small-Interfering RNA Delivery

“…The accumulation of nanogel degradation products in the endosomal lumen induced the disruption of the vesicular membrane, possibly through an osmotic effect, thereby released active siRNA into the cytosol. Dex-HEMA-co-TMAEMA nanogel-mediated sustained gene silencing was also achieved by internalization of PS in the nanogel (Raemdonck et al, 2010). For prolonging gene silencing, PS activation was applied at different timepoints after transfecting with siRNA-nanogel on cells.…”

Comparison of Polymeric siRNA Nanocarriers in a Murine LPS-Activated Macrophage Cell Line: Gene Silencing, Toxicity and Off-Target Gene Expression

“…This degradation was shown to depend on the crosslink density of the gels (and therefore the degree of substitution of the dex-MA or dex-HEMA). It has also been shown that the crosslink density influences siRNA loading and gene silencing efficacy (60). Although dex-MA gels do not degrade as a function of time, reasonably good transfection efficiency is observed.…”

Hybrid pulmonary surfactant-coated nanogels mediate efficient in vivo delivery of siRNA to murine alveolar macrophages

“…Dextran hydroxyethyl methacrylate (dex-HEMA) with a degree of substitution of 5.2 [23] was selected for the preparation of the dextran nanogels based on previous work [24]. Briefly, 150 mg of dex-HEMA was dissolved in a solution containing 97.5 µL irgacure 2959 (10 mg mL -1 in water; Sigma-Aldrich, Bornem, Belgium), 180 µL nuclease-free water and 195 µL of a cationic methacrylate monomer, [2-(methacryloyloxy)-ethyl] trimethylammonium chloride (TMAEMA, 80 wt% solution in water; Sigma-Aldrich).…”