title: siRNA transfection with calcium phosphate nanoparticles stabilized with PEGylated chelators.
abstract: Despite the enormous therapeutic potential of siRNAs, their delivery is still problematic due to unfavorable biodistribution profiles and poor intracellular bioavailability. Calcium phosphate co-precipitate has been used for nearly 40 years for in vitro transfection due to its non-toxic nature and simplicity of preparation. However, rapid particle growth has largely prevented the translation of this method for in vivo purposes. It has recently been shown that bisphosphonate derivatives can physically stabilize calcium phosphate nanoparticles while still allowing for efficient cell transfection with plasmid DNA. Herein, two novel PEGylated chelating agents (PEG-alendronate and PEG-inositolpentakisphosphate) with enhanced stabilizing properties are introduced, and it is demonstrated that the bisphosphonate-stabilized nanoparticles can efficiently deliver siRNA in vitro. The nanoparticles are mainly taken up by clathrin-dependent endocytosis, and acidification of the endosomal compartment is required to release the entrapped siRNA into the cytosol. Furthermore, particle uptake enhances the inhibition of the mevalonate pathway by the bisphosphonate in macrophages.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.
authors.forename: Elisabeth V
authors.initials: EV
authors.lastname: Giger
authors.forename: Bastien
authors.initials: B
authors.lastname: Castagner
authors.forename: Johanna
authors.initials: J
authors.lastname: Räikkönen
authors.forename: Jukka
authors.initials: J
authors.lastname: Mönkkönen
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Leroux
mesh_terms: D000818:Animals; D002130:Calcium Phosphates / Q000737:chemistry*; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000737:chemistry; D005079:Excipients / Q000737:chemistry; D006801:Humans; D008297:Male; D053769:Nanocapsules / Q000008:administration & dosage* / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D011471:Prostatic Neoplasms / Q000235:genetics*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics*; D014162:Transfection / Q000379:methods*
chemical_list: D002130:Calcium Phosphates; D002614:Chelating Agents; D005079:Excipients; D053769:Nanocapsules; D034741:RNA, Small Interfering; C020243:calcium phosphate