title: Lack of repair of rat skull critical size defect treated with bovine morphometric protein bound to microgranular bioabsorbable hydroxyapatite.
abstract: The ability of a pool of bovine bone morphogenetic proteins bound to synthetic microgranular hydroxyapatite (BMPb-HA) to stimulate bone repair was determined in rat critical size defects. An 8-mm diameter defect was created in the calvaria of 25 rats. In 15 rats, the defects were filled with BMPb-HA homogenized with blood (experimental group), and in 10 rats the defects were filled only with blood clots (control). The calvariae of experimental rats were collected 1, 3 and 6 months after surgery and of the control rats at the end of surgery and 6 months thereafter. The morphometric results obtained in the radiographs showed an absence of new bone formation at 1 and 3 months post-surgery and, histologically, the defects were filled with fibrous connective tissue and numerous foci of a foreign body-type granulomatous reaction around hydroxyapatite agglomerates. At the end of 6 months, the number and size of the granulomatous foci decreased and the area of the defects was reduced by 22% compared to the 0-hour control due to the formation of new bone at their borders, although the mean area was similar to the 6-month control. We conclude that the use of BMPb-HA in the treatment of critical size bone defects of the rat skull leads to the formation of a foreign body-type granulomatous reaction that markedly inhibits new bone formation, suggesting that synthetic microgranular hydroxyapatite does not represent a good carrier for BMP-induced bone formation.
authors.affiliation: Department of Biological Sciences, Faculty of Dentistry of Bauru, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Gabriel Ramalho
authors.initials: GR
authors.lastname: Ferreira
authors.forename: Tania Mary
authors.initials: TM
authors.lastname: Cestari
authors.forename: José Mauro
authors.initials: JM
authors.lastname: Granjeiro
authors.forename: Rumio
authors.initials: R
authors.lastname: Taga
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects / Q000627:therapeutic use*; D001769:Blood; D001847:Bone Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use*; D018786:Bone Substitutes / Q000009:adverse effects / Q000627:therapeutic use*; D002417:Cattle; D003238:Connective Tissue / Q000473:pathology; D004337:Drug Carriers; D017886:Durapatite / Q000009:adverse effects / Q000627:therapeutic use*; D005347:Fibroblasts / Q000473:pathology; D015745:Granuloma, Foreign-Body / Q000139:chemically induced / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000473:pathology; D008264:Macrophages / Q000473:pathology; D008297:Male; D010012:Osteogenesis / Q000187:drug effects; D011859:Radiography; D051381:Rats; D012886:Skull / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes; D004337:Drug Carriers; D017886:Durapatite