Biodegradable Dextran Nanogels for RNA Interference: Focusing on Endosomal Escape and Intracellular siRNA Delivery

Abstract

The successful therapeutic application of small interfering RNA (siRNA) largely relies on the development of safe and effective delivery systems that are able to guide the siRNA therapeutics to the cytoplasm of the target cell. In this report, biodegradable cationic dextran nanogels are engineered by inverse emulsion photopolymerization and their potential as siRNA carriers is evaluated. The nanogels are able to entrap siRNA with a high loading capacity, based on electrostatic interaction. Confocal microscopy and flow cytometry analysis reveal that large amounts of siRNA‐loaded nanogels can be internalized by HuH‐7 human hepatoma cells without significant cytotoxicity. Following their cellular uptake, it is found that the nanogels are mainly trafficked towards the endolysosomes. The influence of two different strategies to enhance endosomal escape on the extent of gene silencing is investigated. It is found that both the application of photochemical internalization (PCI) and the use of an influenza‐derived fusogenic peptide (diINF‐7) can significantly improve the silencing efficiency of siRNA‐loaded nanogels. Furthermore, it is shown that an efficient gene silencing requires the degradation of the nanogels. As the degradation kinetics of the nanogels can easily be tailored, these particles show potential for intracellular controlled release of short interfering RNA.

Near‐Infrared‐Light‐Assisted Photothermal Polymerization for Transdermal Hydrogelation and Cell Delivery

“…Cell viability could be maintained at more than 75% after 7 d of incubation although viable cell portions slightly decreased from 92% ± 3% (3 h) to 76% ± 5% (7 d). The cell viability observed in our NAPP‐based RGD‐PEG gels appeared to be compatible with those from other conventional light‐based cell encapsulation techniques …”

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

“…We found a concentrationdependent reduction in the number of viable cells upon exposure to siRNA-formulated nanocarriers with less than 15% reduction for the majority of the polymers (Fig. 3a), compared to 10% in previous reports (19,27,42,44,45). Polyplexes formulated with pHPMA-MPPM induced a drastic decrease in viability at 50-100 nM siRNA, reaching 46% toxicity, which was in contrast to the previously reported 18% toxicity at 80 nM siRNA at a similar N/P ratio (39).…”

Cationic Amphiphilic Drugs Boost the Lysosomal Escape of Small Nucleic Acid Therapeutics in a Nanocarrier-Dependent Manner

“…PCI is a technique that destabilizes endosomal membranes by the application of amphiphilic photosensitizers, which upon photoactivation evoke oxidative endolysosomal membrane damage through the production of ROS. 9,26,66 In line with the observations on CADs, the silencing potential of siRNA-loaded cationic LNPs was unaffected by PCI, whereas the cellular siRNA delivery via dex-(HE)MA siNGs was strongly enhanced. 9,26 As state-of-the-art LNPs are generally PEGylated, the influence of including a PEGylated lipid (DSPE-PEG 2000 ) in the formulation was also probed.…”

“…9,26,66 In line with the observations on CADs, the silencing potential of siRNA-loaded cationic LNPs was unaffected by PCI, whereas the cellular siRNA delivery via dex-(HE)MA siNGs was strongly enhanced. 9,26 As state-of-the-art LNPs are generally PEGylated, the influence of including a PEGylated lipid (DSPE-PEG 2000 ) in the formulation was also probed. Although higher siRNA and LIP concentrations were needed to achieve target gene knockdown compared to the non-PEGylated counterpart, a clear adjuvant effect of DES on the siRNA delivery efficiency could be seen when the DOTAP-DOPE LIPs were modified with 5 mol % of the PEGylated lipid (Figure 5D and Figure S8B).…”