title: Efficient in vitro siRNA delivery and intramuscular gene silencing using PEG-modified PAMAM dendrimers.
abstract: Although siRNA techniques have been broadly applied as a tool for gene knockdown, substantial challenges remain in achieving efficient delivery and in vivo efficacy. In particular, the low efficiency of target gene silencing in vivo is a critical limiting step to the clinical application of siRNA therapies. Poly(amidoamine) (PAMAM) dendrimers are widely used as carriers for drug and gene delivery; however, in vivo siRNA delivery by PAMAM dendrimers remains to be carefully investigated. In this study, the effectiveness of G5 and G6 PAMAM dendrimers with 8% of their surface amines conjugated to MPEG-5000 was studied for siRNA delivery in vitro and for intramuscular in vivo delivery in mice. The results from the PEG-modified dendrimers were compared to the results from the parent dendrimers as well as Lipofectamine 2000 and INTERFERin. Both PEG-modifed dendrimers protect the siRNA from being digested by RNase and gave high transfection efficiency for FITC-labeled siRNA in the primary vascular smooth muscle cells (VSMC) and mouse peritoneal macrophages. The PEG-modified dendrimers achieved knockdown of both plasmid (293A cells) and adenovirus-mediated green fluorescence protein (GFP) expression (Cos7 cells) in vitro with efficiency similar to that shown for Lipofectamine 2000. We further demonstrated in vivo that intramuscular delivery of GFP-siRNA using PEG-modified dendrimer significantly suppressed GFP expression in both transiently adenovirus infected C57BL/6 mice and GFP transgenic mice.
authors.affiliation: Peking University Institute of Cardiovascular Sciences, Peking University Health Science Center, Peking University, 38 Xueyuan Road, Beijing, 100083, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Tang
authors.forename: Yang-Bing
authors.initials: YB
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Ri-Yuan
authors.initials: RY
authors.lastname: Lin
authors.forename: Mallory
authors.initials: M
authors.lastname: van Dongen
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Zurcher
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Gu
authors.forename: Mark M
authors.initials: MM
authors.lastname: Banaszak Holl
authors.forename: George
authors.initials: G
authors.lastname: Liu
authors.forename: Rong
authors.initials: R
authors.lastname: Qi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D019556:COS Cells; D002460:Cell Line; D006224:Cricetinae; D050091:Dendrimers / Q000737:chemistry*; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D020868:Gene Silencing / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics*
chemical_list: D050091:Dendrimers; C522249:PEG-PAMAM; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D011092:Polyethylene Glycols; D016650:Fluorescein-5-isothiocyanate