title: Implantation of silicon dioxide-based nanocrystalline hydroxyapatite and pure phase beta-tricalciumphosphate bone substitute granules in caprine muscle tissue does not induce new bone formation.
abstract: BACKGROUND
  Osteoinductive bone substitutes are defined by their ability to induce new bone formation even at heterotopic implantation sites. The present study was designed to analyze the potential osteoinductivity of two different bone substitute materials in caprine muscle tissue.
  
  
  METHODS
  One gram each of either a porous beta-tricalcium phosphate (β-TCP) or an hydroxyapatite/silicon dioxide (HA/SiO2)-based nanocrystalline bone substitute material was implanted in several muscle pouches of goats. The biomaterials were explanted at 29, 91 and 181 days after implantation. Conventional histology and special histochemical stains were performed to detect osteoblast precursor cells as well as mineralized and unmineralized bone matrix.
  
  
  RESULTS
  Both materials underwent cellular degradation in which tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells and TRAP-negative multinucleated giant cells were involved. The ß-TCP was completely resorbed within the observation period, whereas some granules of the HA-groups were still detectable after 180 days. Neither osteoblasts, osteoblast precursor cells nor extracellular bone matrix were found within the implantation bed of any of the analyzed biomaterials at any of the observed time points.
  
  
  CONCLUSIONS
  This study showed that ß-TCP underwent a faster degradation than the HA-based material. The lack of osteoinductivity for both materials might be due to their granular shape, as osteoinductivity in goat muscle has been mainly attributed to cylindrical or disc-shaped bone substitute materials. This hypothesis however requires further investigation to systematically analyze various materials with comparable characteristics in the same experimental setting.
authors.affiliation: Institute of Pathology, REPAIR-Lab, Johannes Gutenberg University Mainz, Langenbeckstrasse 1, Mainz, 55101, Germany. ghanaati@uni-mainz.de
authors.forename: Shahram
authors.initials: S
authors.lastname: Ghanaati
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Udeabor
authors.forename: Mike
authors.initials: M
authors.lastname: Barbeck
authors.forename: Ines
authors.initials: I
authors.lastname: Willershausen
authors.forename: Oliver
authors.initials: O
authors.lastname: Kuenzel
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sader
authors.forename: C James
authors.initials: CJ
authors.lastname: Kirkpatrick
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D018786:Bone Substitutes / Q000737:chemistry / Q000627:therapeutic use*; D002130:Calcium Phosphates / Q000627:therapeutic use*; D004338:Drug Combinations; D017886:Durapatite / Q000627:therapeutic use*; D005260:Female; D006041:Goats; D023421:Models, Animal; D009132:Muscles; D053758:Nanoparticles; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology*; D012822:Silicon Dioxide / Q000627:therapeutic use*; D060327:Solid-Phase Synthesis Techniques
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D002130:Calcium Phosphates; D004338:Drug Combinations; C534915:NanoBone; C485817:beta-tricalcium phosphate; D012822:Silicon Dioxide; D017886:Durapatite