title: The slow resorption with replacement by bone of a hydrothermally synthesized pure calcium-deficient hydroxyapatite.
abstract: A newly developed calcium-deficient hydroxyapatite composed of rod-shaped particles synthesized by the hydrothermal method (HHA) and stoichiometric hydroxyapatite (SHA) synthesized by the sintering method was used for in vivo implantation and in vitro culture systems to compare these biological responses. In the rabbit femur, implanted HHA was slowly resorbed and about 80% of the implant remained 24 weeks after implantation; however, up to 72 weeks after implantation, most of the implanted HHA was resorbed. The implanted SHA was unresorbed throughout the experimental period, but degradation by the invasion of newly formed bone was seen at 72 weeks after implantation. Bone histomorphometry showed that the volume of newly formed bone and the number of osteoclasts in the implanted region were significantly higher in HHA than in SHA 24 weeks after implantation. In vitro culture of C2C12 cells with the induction of osteoblastic phenotypes using recombinant bone morphogenetic protein-2 showed similar cell density and the induction of alkaline phosphatase activity between the cells on HHA and SHA discs. In vitro osteoclastogenesis of HHA and SHA discs using bone marrow macrophages and recombinant receptor activator of nuclear factor-kappaB ligand showed higher TRAP activity of osteoclasts cultured on HHA discs. These results showed that slow biodegradability did not always correlate to final replaceability in bone tissue, and suggested that the activity of osteoclasts correlated to the bone-forming activity of osteoblasts.
authors.affiliation: Department of Oral Pathology and Bone Metabolism, Unit of Basic Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Okuda
authors.forename: Koji
authors.initials: K
authors.lastname: Ioku
authors.forename: Ikuho
authors.initials: I
authors.lastname: Yonezawa
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Minagi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Gonda
authors.forename: Giichiro
authors.initials: G
authors.lastname: Kawachi
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kamitakahara
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Shibata
authors.forename: Hisashi
authors.initials: H
authors.lastname: Murayama
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kurosawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D001862:Bone Resorption / Q000378:metabolism*; D018786:Bone Substitutes / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000737:chemistry*; D002460:Cell Line; D017886:Durapatite / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis; D011817:Rabbits; D014056:Tomography, X-Ray
chemical_list: D001672:Biocompatible Materials; D018786:Bone Substitutes; D017886:Durapatite; D002118:Calcium