Hui Yi Xue1, Mayuri Narvikar, Juan-Bao Zhao, Ho Lun Wong. 1. Department of Pharmaceutical Sciences, Temple University School of Pharmacy, 3307 North Broad Street, Philadelphia, Pennsylvania 19140, USA.
Abstract
PURPOSE: Clinical application of cationic polymers for delivery of nucleic acids has been limited by their toxicity. The purpose of this study is to evaluate whether the polymer-in-lipid hybrid nanotechnology recently developed for controlled siRNA delivery can tackle this toxicity issue by reducing exposure of the cellular components to free cationic polymers. METHODS: Lipid-polymer hybrid nanocarriers (LPNs) encapsulating complexes of hexadecylated polyethylenimine (H-PEI) and biologically inactive siRNA in lipids were prepared at different lipid-polymer ratios. Comparative toxicity of these LPNs and unencapsulated cationic materials on breast epithelial cell lines MDA-MB-231 and MCF-10a was evaluated. RESULTS: Even at a low lipid-polymer ratio (3:1 w/w), encapsulation of H-PEI improved its LC(50) values measured within hours by 3-5 fold, and caused less reduction in the colony-formation rates in 10-14 days. The observed reductions in the acute and delayed carrier toxicity were associated with significantly less membrane damages, improved mitochondrial functions, reduced reactive oxidative species production, and lower caspase-3 activity (all p < 0.05) without sacrificing the siRNA transfection efficiency. CONCLUSIONS: This study has validated the hybrid nanotechnology for controlled RNA delivery from a toxicological perspective. This is especially valuable if local or long-term RNA therapy is intended for which low carrier toxicity is essential.
PURPOSE: Clinical application of cationic polymers for delivery of nucleic acids has been limited by their toxicity. The purpose of this study is to evaluate whether the polymer-in-lipid hybrid nanotechnology recently developed for controlled siRNA delivery can tackle this toxicity issue by reducing exposure of the cellular components to free cationic polymers. METHODS:Lipid-polymer hybrid nanocarriers (LPNs) encapsulating complexes of hexadecylated polyethylenimine (H-PEI) and biologically inactive siRNA in lipids were prepared at different lipid-polymer ratios. Comparative toxicity of these LPNs and unencapsulated cationic materials on breast epithelial cell lines MDA-MB-231 and MCF-10a was evaluated. RESULTS: Even at a low lipid-polymer ratio (3:1 w/w), encapsulation of H-PEI improved its LC(50) values measured within hours by 3-5 fold, and caused less reduction in the colony-formation rates in 10-14 days. The observed reductions in the acute and delayed carrier toxicity were associated with significantly less membrane damages, improved mitochondrial functions, reduced reactive oxidative species production, and lower caspase-3 activity (all p < 0.05) without sacrificing the siRNA transfection efficiency. CONCLUSIONS: This study has validated the hybrid nanotechnology for controlled RNA delivery from a toxicological perspective. This is especially valuable if local or long-term RNA therapy is intended for which low carrier toxicity is essential.
Authors: Kai K Ewert; Alexandra Zidovska; Ayesha Ahmad; Nathan F Bouxsein; Heather M Evans; Christopher S McAllister; Charles E Samuel; Cyrus R Safinya Journal: Top Curr Chem Date: 2010