title: Biodegradable calcium phosphate nanoparticle with lipid coating for systemic siRNA delivery.
abstract: A lipid coated calcium phosphate (LCP) nanoparticle (NP) formulation was developed for efficient delivery of small interfering RNA (siRNA) to a xenograft tumor model by intravenous administration. Based on the previous formulation, liposome-polycation-DNA (LPD), which was a DNA-protamine complex wrapped by cationic liposome followed by post-insertion of PEG, LCP was similar to LPD NP except that the core was replaced by a biodegradable nano-sized calcium phosphate precipitate prepared by using water-in-oil micro-emulsions in which siRNA was entrapped. We hypothesized that after entering the cells, LCP would de-assemble at low pH in the endosome, which would cause endosome swelling and bursting to release the entrapped siRNA. Such a mechanism was demonstrated by the increase of intracellular Ca(2+) concentration as shown by using a calcium specific dye Fura-2. The LCP NP was further modified by post-insertion of polyethylene glycol (PEG) with or without anisamide, a sigma-1 receptor ligand for systemic administration. Luciferase siRNA was used to evaluate the gene silencing effect in H-460 cells which were stably transduced with a luciferase gene. The anisamide modified LCP NP silenced about 70% and 50% of luciferase activity for the tumor cells in culture and those grown in a xenograft model, respectively. The untargeted NP showed a very low silencing effect. The new formulation improved the in vitro silencing effect 3-4 folds compared to the previous LPD formulation, but had a negligible immunotoxicity.
authors.affiliation: Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Yun-Ching
authors.initials: YC
authors.lastname: Chen
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Tseng
authors.forename: Subho
authors.initials: S
authors.lastname: Mozumdar
authors.forename: Leaf
authors.initials: L
authors.lastname: Huang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002130:Calcium Phosphates / Q000737:chemistry* / Q000633:toxicity; D045744:Cell Line, Tumor; D020099:Coated Materials, Biocompatible / Q000737:chemistry* / Q000633:toxicity; D016207:Cytokines / Q000276:immunology; D004337:Drug Carriers / Q000737:chemistry* / Q000633:toxicity; D004339:Drug Compounding; D005260:Female; D020868:Gene Silencing / Q000187:drug effects; D007275:Injections, Intravenous; D008055:Lipids / Q000737:chemistry* / Q000633:toxicity; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry / Q000633:toxicity; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D016207:Cytokines; D004337:Drug Carriers; D008055:Lipids; D034741:RNA, Small Interfering; D011092:Polyethylene Glycols; C020243:calcium phosphate; D008156:Luciferases; D002118:Calcium