title: Local delivery of siRNA using a biodegradable polymer application to enhance BMP-induced bone formation.
abstract: Small interfering RNA (siRNA) is useful tool for specific and efficient knockdown of disease-related genes. However, in vivo applications of siRNA are limited due to difficulty in its efficient delivery to target cells. In this study, we investigated the efficacy of a biodegradable hydrogel, poly-d,l-lactic acid-p-dioxanone-polyethylene glycol block co-polymer (PLA-DX-PEG), as a siRNA carrier. PLA-DX-PEG pellets with or without fluorescein-labeled dsRNA were implanted into mouse dosal muscle pouches. The cellular uptake of dsRNA surround the polymer was confirmed by fluorescent microscopy. The fluorescence intensity was dose-dependent of the dsRNA, and exhibited a time-dependent decrease. To investigate its biological efficiency, noggin (antagonoist to BMPs) gene-silencing with siRNA (siRNA/Noggin) was examined by the amount of suppression of BMP-2-induced noggin expression and the level of performance of BMP, indicated by ectopic bone formation. Noggin gene expression induced by BMP-2 was suppressed by addition of siRNA/Noggin to the implant, and the ectopic bone formation induced by implants with both BMP-2 and siRNA/Noggin was significantly greater than those induced by implants with BMP-2 alone. These results indicate the efficacy of local delivery of siRNAs by PLA-DX-PEG polymer, which intensified bone-inducing effects of BMP and promoted new bone formation by suppressing gene expression of Noggin.
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Abenoku Asahimachi, Osaka 545-8585, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Manaka
authors.forename: Akinobu
authors.initials: A
authors.lastname: Suzuki
authors.forename: Kazushi
authors.initials: K
authors.lastname: Takayama
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Imai
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Kunio
authors.initials: K
authors.lastname: Takaoka
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001673:Biodegradation, Environmental / Q000187:drug effects; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D019793:Fluorescein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D018014:Gene Transfer Techniques; D006801:Humans; D007150:Immunohistochemistry; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D007773:Lactates / Q000737:chemistry*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008856:Microscopy, Fluorescence; D009132:Muscles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012330:RNA, Double-Stranded / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D011859:Radiography; D011994:Recombinant Proteins / Q000494:pharmacology; D013194:Staining and Labeling; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D000099176:Noggin Protein
chemical_list: D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2; D002352:Carrier Proteins; D019793:Fluorescein; D007773:Lactates; D011092:Polyethylene Glycols; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D000099176:Noggin Protein; C432470:polylactic acid-dioxanone-polyethylene glycol block copolymer; C499469:recombinant human bone morphogenetic protein-2