title: PEGylated cyclodextrins as novel siRNA nanosystems: correlations between polyethylene glycol length and nanoparticle stability.
abstract: Silencing disease-related genes in the central nervous system (CNS) using short interfering RNA (siRNA) holds great promise for treating neurological disorders. Yet, delivery of RNAi therapeutics to the brain poses major challenges to non-viral systems, especially when considering systemic administration. Cationic nanoparticles have been widely investigated for siRNA delivery, but the tendency of these to aggregate in physiological environments limits their intravenous application. Thus, strategies to increase the stability of nanoparticles have been developed. Here, we investigated the ability of modified cationic amphiphilic or PEGylated amphiphilic cyclodextrins (CD) to formulate stable CD.siRNA nanoparticles. To this end, we describe a simple method for post-modification of pre-formed cationic CD.siRNA nanoparticles at their surface using PEGylated CDs of different PEG lengths. PEGylated CD.siRNA nanoparticles presented reduced surface charges and increased stability in physiological salt conditions. Stability of PEGylated CD.siRNA nanoparticles in vitro increased with both PEG length and PEG density at the surface. Furthermore, in a comparative pharmacokinetic study, increased systemic exposure and reduced clearance were achieved with CD-formulations when compared to naked siRNAs. However, no significant differences were observed among non-PEGylated and PEGylated CD.siRNAs suggesting that longer PEG lengths might be required for improving stability in vivo.
authors.affiliation: Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland; Department Anatomy and Neuroscience, University College Cork, Cork, Ireland.
authors.forename: Bruno M D C
authors.initials: BM
authors.lastname: Godinho
authors.affiliation: Centre for synthesis and Chemical Biology, University College Dublin, Dublin, Ireland.
authors.forename: Julien R
authors.initials: JR
authors.lastname: Ogier
authors.affiliation: Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland.
authors.forename: Aoife
authors.initials: A
authors.lastname: Quinlan
authors.affiliation: Centre for synthesis and Chemical Biology, University College Dublin, Dublin, Ireland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Darcy
authors.affiliation: Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Griffin
authors.affiliation: Department Anatomy and Neuroscience, University College Cork, Cork, Ireland; Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Cork, Ireland.
authors.forename: John F
authors.initials: JF
authors.lastname: Cryan
authors.affiliation: Pharmacodelivery Group, School of Pharmacy, University College Cork, Cork, Ireland. Electronic address: caitriona.odriscoll@ucc.ie.
authors.forename: Caitriona M
authors.initials: CM
authors.lastname: O'Driscoll
mesh_terms: D000818:Animals; D004355:Drug Stability; D008297:Male; D008807:Mice, Inbred BALB C; D053758:Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D034741:RNA, Small Interfering; D050486:Serotonin Plasma Membrane Transport Proteins; C493231:Slc6a4 protein, mouse; D047392:beta-Cyclodextrins; D011092:Polyethylene Glycols
keywords: Aggregation; Cyclodextrin; PEGylation; Pharmacokinetics; Post-modification; siRNA delivery