title: Surface immobilization of bone morphogenetic protein 2 via a self-assembled monolayer formation induces cell differentiation.
abstract: Bone extracellular matrix consists of a network of proteins in which growth factors, like bone morphogenetic protein 2 (BMP-2), are embedded and released upon matrix turnover and degradation. Recombinant human (rh)BMP-2 shows promise in enhancing bone fracture repair, although issues regarding finding a suitable delivery system still limit its extensive clinical use. The aim of this study is to determine which cell activities are triggered by the presentation of immobilized rhBMP-2. For this purpose gold surfaces were first decorated with a self-assembled monolayer consisting of a hetero-bifunctional linker. rhBMP-2 was covalently bound to the surfaces via this linker and used to investigate the cellular responses of C2C12 myoblasts. We show that covalently immobilized rhBMP-2 (iBMP-2) initiates short-term signaling events. Using a BMP-responsive reporter gene assay and western blotting to monitor phosphorylation of Smad1/5/8 we prove that iBMP-2 activates BMP-dependent signal transduction. Furthermore, we demonstrate that iBMP-2 suppresses myotube formation and promotes the osteoblast phenotype in C2C12 cells. The bioactivity of surface-bound rhBMP-2 presented in this study is not due to its release into the medium. As such, our simple approach paves the way for the controlled local presentation of immobilized growth factors, limiting degradation while still maintaining biological activity.
authors: Department of Biophysical Chemistry, Institute for Physical Chemistry, University of Heidelberg, INF 253, 69120 Heidelberg, Germany.
authors: Theresa L M
authors: TL
authors: Pohl
authors: Jan H
authors: JH
authors: Boergermann
authors: Gerburg K
authors: GK
authors: Schwaerzer
authors: Petra
authors: P
authors: Knaus
authors: Elisabetta A
authors: EA
authors: Cavalcanti-Adam
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D003470:Culture Media / Q000737:chemistry; D006801:Humans; D055767:Immobilized Proteins / Q000494:pharmacology*; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000378:metabolism; D013499:Surface Properties / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D055396:Bone Morphogenetic Protein 2; D003470:Culture Media; D055767:Immobilized Proteins; D011994:Recombinant Proteins; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D008156:Luciferases