title: BMP-2 gene-fibronectin-apatite composite layer enhances bone formation.
abstract: BACKGROUND
  Safe and efficient gene transfer systems are needed for tissue engineering. We have developed an apatite composite layer including the bone morphogenetic protein-2 (BMP-2) gene and fibronectin (FB), and we evaluated its ability to induce bone formation.
  
  
  METHODS
  An apatite composite layer was evaluated to determine the efficiency of gene transfer to cells cultured on it. Cells were cultured on a composite layer including the BMP-2 gene and FB, and BMP-2 gene expression, BMP-2 protein concentrations, alkaline phosphatase (ALP) activity, and osteocalcin (OC) concentrations were measured. A bone defect on the cranium of rats was treated with hydroxyapatite (HAP)-coated ceramic buttons with the apatite composite layer including the BMP-2 gene and FB (HAP-BMP-FB). The tissue concentration of BMP-2, bone formation, and the expression levels of the BMP-2, ALP, and OC genes were all quantified.
  
  
  RESULTS
  The apatite composite layer provided more efficient gene transfer for the cultured cells than an apatite composite layer without FB. The BMP-2 concentration was approximately 100-600 pg/mL in the cell-culture medium. Culturing the cells on the apatite composite layer for 27 days increased ALP activity and OC concentrations. In animal experiments, the tissue concentrations of BMP-2 were over 100 pg/mg in the HAP-BMP-FB group and approximately 50 pg/mg in the control groups. Eight weeks later, bone formation was more enhanced in the HAP-BMP-FB group than in the control groups. In the tissues surrounding the HAP button, the gene expression levels of ALP and OC increased.
  
  
  CONCLUSIONS
  The BMP-2 gene-FB-apatite composite layer might be useful for bone engineering.
authors.affiliation: Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Hideo
authors.initials: H
authors.lastname: Tsurushima
authors.forename: Ayako
authors.initials: A
authors.lastname: Oyane
authors.forename: Yushin
authors.initials: Y
authors.lastname: Yazaki
authors.forename: Yu
authors.initials: Y
authors.lastname: Sogo
authors.forename: Atsuo
authors.initials: A
authors.lastname: Ito
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002130:Calcium Phosphates / Q000378:metabolism; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D017886:Durapatite / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005353:Fibronectins / Q000502:physiology*; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008855:Microscopy, Electron, Scanning; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology*; D010957:Plasmids / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012886:Skull / Q000293:injuries / Q000601:surgery; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C480020:Atrnl1 protein, mouse; D055396:Bone Morphogenetic Protein 2; D002130:Calcium Phosphates; D017931:DNA Primers; D005353:Fibronectins; D008565:Membrane Proteins; D015675:Osteocalcin; D017886:Durapatite; C020243:calcium phosphate; D000469:Alkaline Phosphatase