Comparison of polymeric siRNA nanocarriers in a murine LPS-activated macrophage cell line: Gene silencing, toxicity and off-target gene expression

Purpose: Tumor necrosis factor α (TNF-α) plays a key role in the progression of rheumatoid arthritis and is an important target for anti-rheumatic therapies. TNF-α expression can be silenced with small interfering RNA (siRNA), but efficacy is dependent on efficient and safe siRNA delivery vehicles. We aimed to identify polymeric nanocarriers for anti-TNF-α siRNA with optimal efficacy and minimal off-target effects in vitro. Methods: TNF-α silencing with polymeric siRNA nanocarriers was compared in lipopolysaccharide-activated RAW 264.7 macrophages by real-time reverse transcription (RT)-PCR. Expression of non-target genes involved in inflammation, apoptosis, and cell cycle progression was determined by RTPCR, toxicity evaluated by propidium iodide and annexin V staining. Results: PAMAM dendrimers (G4 and G7) and dextran nanogels mediated remarkably high concentration-dependent gene silencing and low toxicity; dioleoyltrimethylammoniumpropane-modified poly (DL-lactide-co-glycolide acid) nanoparticles, thiolated, trimethylated chitosan and poly[(2-hydroxypropyl) methacrylamide 1-methyl-2-piperidine methanol] polyplexes were less efficient transfectants. There were minor changes in the regulation of off-target genes, mainly dependent on nanocarrier and siRNA concentration. Conclusions: Dextran nanogels and PAMAM dendrimers mediated high gene silencing with minor toxicity and offtarget transcriptional changes and are therefore expected to be suitable siRNA delivery systems in vivo.