title: Immunohistochemical characterization of nanocrystalline hydroxyapatite silica gel (NanoBone(r)) osteogenesis: a study on biopsies from human jaws.
abstract: OBJECTIVE
  Bone substitute biomaterials may be osteogenic, osteoconductive or osteoinductive. To test for these probable characteristics in a new nanoporous grafting material consisting of nanocrystalline hydroxyapatite embedded in a porous silica gel matrix (NanoBone(s)), applied in humans, we studied biopsies from 12 patients before dental implantation following various orofacial augmentation techniques with healing times of between 3.5 and 12 months.
  
  
  METHODS
  Sections from decalcified specimens were investigated using histology, histochemistry [periodic acid Schiff, alcian blue staining and tartrate-resistant acid phosphatase (TRAP)] and immunohistochemistry, with markers for osteogenesis, bone remodelling, resorption and vessel walls (alkaline phosphatase, bone morphogenetic protein-2, collagen type I, ED1, osteocalcin, osteopontin, runx2 and Von-Willebrand factor).
  
  
  RESULTS
  Histologically, four specific stages of graft transformation into lamellar bone could be characterized. During early stages of healing, bone matrix proteins were absorbed by NanoBone(s) granules, forming a proteinaceous matrix, which was invaded by small vessels and cells. We assume that the deposition of these molecules promotes early osteogenesis in and around NanoBone(s) and supports the concomitant degradation probably by osteoclast-like cells. TRAP-positive osteoclast-like cells were localized directly on the granular surfaces. Runx2-immunoreactive pre-osteoblasts, which are probably involved in direct osteogenesis forming woven bone that is later transformed into lamellar bone, were attracted. Graft resorption and bone apposition around the graft granules appear concomitantly.
  
  
  CONCLUSIONS
  We postulate that NanoBone(s) has osteoconductive and biomimetic properties and is integrated into the host's physiological bone turnover at a very early stage.
authors.affiliation: Department of Orthodontics, Oral Biology Laboratory, University of Bonn, Dental Hospital, Bonn, Germany. wgoetz@uni-bonn.de
authors.forename: Werner
authors.initials: W
authors.lastname: Götz
authors.forename: Thomas
authors.initials: T
authors.lastname: Gerber
authors.forename: Barbara
authors.initials: B
authors.lastname: Michel
authors.forename: Stefan
authors.initials: S
authors.lastname: Lossdörfer
authors.forename: Kai-Olaf
authors.initials: KO
authors.lastname: Henkel
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Heinemann
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000032:analysis; D000540:Alveolar Ridge Augmentation / Q000379:methods*; D015415:Biomarkers / Q000032:analysis; D055396:Bone Morphogenetic Protein 2 / Q000032:analysis; D016723:Bone Remodeling / Q000187:drug effects; D001862:Bone Resorption / Q000473:pathology; D018786:Bone Substitutes / Q000627:therapeutic use*; D024042:Collagen Type I / Q000032:analysis; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D004338:Drug Combinations; D017886:Durapatite / Q000627:therapeutic use*; D053331:Ectodysplasins / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D005782:Gels; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008875:Middle Aged; D053758:Nanoparticles / Q000627:therapeutic use*; D010006:Osteoblasts / Q000473:pathology; D015675:Osteocalcin / Q000032:analysis; D010010:Osteoclasts / Q000473:pathology; D010012:Osteogenesis / Q000187:drug effects*; D053495:Osteopontin / Q000032:analysis; D058428:Silica Gel; D012822:Silicon Dioxide / Q000627:therapeutic use*; D000071681:Tartrate-Resistant Acid Phosphatase; D055815:Young Adult; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: C525718:BMP2 protein, human; D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; D018786:Bone Substitutes; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D004338:Drug Combinations; C506018:EDA protein, human; D053331:Ectodysplasins; D005782:Gels; D007527:Isoenzymes; C534915:NanoBone; C493709:RUNX2 protein, human; D014841:von Willebrand Factor; D015675:Osteocalcin; D053495:Osteopontin; D058428:Silica Gel; D012822:Silicon Dioxide; D017886:Durapatite; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase