Shape-Specific Hydrogel Nanoparticles with Defined Composition and Surface Properties for Gene Silencing Public Deposited

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Last Modified
  • March 21, 2019
Creator
  • Dunn, Stuart
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Diseases and disorders may be treated through RNA interference (RNAi), a natural post-transcriptional gene silencing event. Synthetic small interfering RNAs (siRNAs) may be designed to target specific genes for down-regulation in RNAi therapies. In the delivery of siRNA to target cells in vivo, numerous challenges are encountered such as susceptibility to degradation by RNases, clearance by the reticuloendothelial system, low internalization by cells, and endosomal escape. siRNA may be chemically modified or associated with lipid- or polymer-based particulate vehicles to enhance in vivo stability, increase bioavailability, improve transfection, facilitate accumulation in particular tissues, and enable cell-specific gene silencing. Independent control over the physicochemical properties of nanoparticles in the delivery of siRNA was enabled through a particle molding process that is a unique off-shoot of soft lithography known as PRINT® (Particle Replication in Non-wetting Templates) technology. Cationic hydrogel nanoparticles were tested using biocompatible poly(vinyl pyrrolidone)- and poly(ethylene glycol) (PEG)-based matrices for their ability to physically encapsulate and deliver siRNA to target cells. Effective gene silencing was observed in vitro using PEGylated hydrogel nanoparticles without inducing cytotoxicity. Functionalization of particles with maleic anhydride-derivatized ligands was pursued to produce a wholly acid-labile system capable of targeting the transferrin receptor, endosomal escape, and delivery of siRNA. To maximize retention of siRNA within hydrogel nanoparticles during systemic administration or functionalization with ligands, a pro-drug strategy was sought for covalent incorporation and triggered intracellular release of siRNA. Gene silencing efficiency and biocompatibility were optimized in the pro-drug siRNA system by screening the amine content of nanoparticles. When control cargos were implemented in the preparation of hydrogels, only target-specific, releasable siRNA cargo elicited gene knockdown. In effort to treat liver diseases, nanoparticles were functionalized with ligands targeting hepatocytes, cells of liver parenchyma implicated in diseases. Ligand-decorated nanoparticles were selectively internalized by hepatocytes in vitro and accumulated in hepatocytes in vivo. Hydrogel nanoparticles coated with ligands reduced target liver gene expression after administration to mice. Further investigation and exploration of this system will hopefully enable efficacious in vivo RNAi therapies in the treatment of numerous diseases.
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  • In Copyright
Advisor
  • DeSimone, Joseph M.
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill
Graduation year
  • 2012
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