title: Osteoinductive recombinant silk fusion proteins for bone regeneration.
abstract: Protein polymers provide a unique opportunity for tunable designs of material systems due to the genetic basis of sequence control. To address the challenge of biomineralization interfaces with protein based materials, we genetically engineered spider silks to design organic-inorganic hybrid systems. The spider silk inspired domain (SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQGT)15served as an organic scaffold to control material stability and to allow multiple modes of processing, whereas the hydroxyapatite binding domain VTKHLNQISQSY (VTK), provided control over osteogenesis. The VTK domain was fused either to the N-, C- or both terminals of the spider silk domain to understand the effect of position on material properties and mineralization. The addition of the VTK domain to silk did not affect the physical properties of the silk recombinant constructs, but it had a critical role in the induction of biomineralization. When the VTK domain was placed on both the C- and N-termini the formation of crystalline hydroxyapatite was significantly increased. In addition, all of the recombinant proteins in film format supported the growth and proliferation of human mesenchymal stem cells (hMSCs). Importantly, the presence of the VTK domain enhanced osteoinductive properties up to 3-fold compared to the control (silk alone without VTK). Therefore, silk-VTK fusion proteins have been shown suitable for mineralization and functionalization for specific biomedical applications.
  
  
  
  Organic-inorganic interfaces are integral to biomaterial functions in many areas of repair and regeneration. Several protein polymers have been investigated for this purpose. Despite their success the limited options to fine-tune their material properties, degradation patterns and functionalize them for each specific biomedical application limits their application. Various studies have shown that the biological performance of such proteins can be improved by genetic engineering. The present study provides data relating protein design parameters and functional outcome quantified by biomineralization and human mesenchymal stem cell differentiation. As such, it helps the design of osteoinductive recombinant biomaterials for bone regeneration.
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, United States.
authors.forename: Nina
authors.initials: N
authors.lastname: Dinjaski
authors.affiliation: Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK.
authors.forename: Robyn
authors.initials: R
authors.lastname: Plowright
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, United States.
authors.forename: Shun
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Belton
authors.affiliation: Biomolecular and Materials Interface Research Group, Interdisciplinary Biomedical Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK. Electronic address: Carole.Perry@ntu.ac.uk.
authors.forename: Carole C
authors.initials: CC
authors.lastname: Perry
authors.affiliation: Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, United States. Electronic address: David.Kaplan@Tufts.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Kaplan
mesh_terms: D001672:Biocompatible Materials / Q000494:pharmacology; D001861:Bone Regeneration / Q000187:drug effects*; D002113:Calcification, Physiologic / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D058574:Integrin-Binding Sialoprotein / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects; D016348:Osseointegration / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000494:pharmacology*; D047011:Silk / Q000737:chemistry*; D012996:Solutions; D055672:Static Electricity; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D058574:Integrin-Binding Sialoprotein; D010455:Peptides; D011993:Recombinant Fusion Proteins; D047011:Silk; D012996:Solutions
keywords: Biomaterials; Calcification; Fusion proteins; Hydroxyapatite; Silk; Spider silk