Dendrimer-Inspired Nanomaterials for the in Vivo Delivery of siRNA to Lung Vasculature

Abstract

Targeted RNA delivery to lung endothelial cells has the potential to treat conditions that involve inflammation, such as chronic asthma and obstructive pulmonary disease. To this end, chemically modified dendrimer nanomaterials were synthesized and optimized for targeted small interfering RNA (siRNA) delivery to lung vasculature. Using a combinatorial approach, the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length. The top performing materials from in vivo screens were found to primarily target Tie2-expressing lung endothelial cells. At high doses, the dendrimer–lipid derivatives did not cause chronic increases in proinflammatory cytokines, and animals did not suffer weight loss due to toxicity. We believe these materials have potential as agents for the pulmonary delivery of RNA therapeutics.

Dendrimer-RNA nanoparticles generate protective immunity against lethal Ebola, H1N1 influenza, and Toxoplasma gondii challenges with a single dose

“…The MDNP nanomaterial has been established not to cause systemic increases in inflammatory cytokines in vivo at doses an order of magnitude greater than used for the immunizations described in this report (49,50). The particle preparations used in these studies are free of infectious contaminants and virtually endotoxin-free [<0.228 endotoxin units per milliliter, which is 40-fold lower than an acceptable endotoxin burden for viral/nonviral vectors (63)].…”

“…1D). The VEEV replicon RNA was formulated into MDNPs using a microfluidic-based production method (49,50).…”

“…The MDNP delivery technology does not generate a systemic increase in inflammatory cytokine production, including IFN, when using doses 500-fold higher than the doses required for Ebola and T. gondii protection (49,50), which is helpful because a strong, early IFN response may impede alphavirus replication, and thus limit the dose of antigen over time (35,36). Furthermore, complete protection in both disease models and prolonged antigenspecific T-cell responses (at least 10 d postvaccination) were achieved in the absence of adjuvants, which are commonly used to increase the inflammatory response (13).…”

“…Nanoparticles were formulated using a microfluidic mixing device as described previously (49,50). Briefly, modified dendrimer and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (Avanti Polar Lipids) were combined in ethanol.…”

“…Immunized mice were inoculated by intranasal administration of a lethal dose [5 × 10 4 chicken embryo infectious dose 50% (CEID 50 )] of influenza A/NWS/33 (H1N1; American Type Culture Collection), which, in our hands, kills 100% of infected BALB/c mice in under 9 d. Body weight was monitored daily, and mice were euthanized when over 20% loss was observed. Mice were considered recovered when preinfection body weight was surpassed, and their health was monitored for an additional 3 wk to ensure no clinical signs of infection were observed.…”