title: pH-triggered nanoparticle mediated delivery of siRNA to liver cells in vitro and in vivo.
abstract: Recently, we reported for the first time the development of pH-triggered nanoparticles for the functional delivery of small interfering RNA (siRNA) to liver for treatment of hepatitis B virus infections in vivo. Here, we report on systematic formulation and biophysical studies of three different pH-triggered nanoparticle formulations looking for ways to improve on the capabilities of our previous nanoparticle system. We demonstrate how pH-triggered, PEGylated siRNA nanoparticles stable with respect to aggregation in 80% serum can still release siRNA payload at pH 5.5 within 30 min. This capability allows functional delivery to cultured murine hepatocyte cells in vitro, despite a high degree of PEGylation (5 mol %). We also demonstrate that pH-triggered, PEGylated siRNA nanoparticles typically enter cells by clathrin-coated pit endocytosis, but functional delivery requires membrane fusion events (fusogenicity). Biodistribution studies indicate that >70% of our administered nanoparticles are found in liver hepatocytes, post intravenous administration. Pharmacodynamic experiments show siRNA delivery to murine liver effecting maximum knockdown 48 h post administration from a single dose, while control (nontriggered) nanoparticles require 96 h and two doses to demonstrate the same effect. We also describe an anti-hepatitis C virus (HCV) proof-of-concept experiment indicating the possibility of RNAi therapy for HCV infections using pH-triggered, PEGylated siRNA nanoparticles.
authors.affiliation: Imperial College Genetic Therapies Centre, Department of Chemistry, Flowers Building, Armstrong Road, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Soumia
authors.initials: S
authors.lastname: Kolli
authors.forename: Suet-Ping
authors.initials: SP
authors.lastname: Wong
authors.forename: Richard
authors.initials: R
authors.lastname: Harbottle
authors.forename: Brian
authors.initials: B
authors.lastname: Johnston
authors.forename: Maya
authors.initials: M
authors.lastname: Thanou
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Miller
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005260:Female; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics*
chemical_list: D034741:RNA, Small Interfering