title: Synthetic octacalcium phosphate augments bone regeneration correlated with its content in collagen scaffold.
abstract: Previous studies have shown that synthetic octacalcium phosphate (OCP) facilitates in vitro osteoblastic cell differentiation in an OCP dose-dependent manner and that a complex of OCP and collagen (OCP/collagen) enhances critical-sized rat calvaria defects more than OCP alone. The present study was designed to investigate whether the bone regenerative properties of OCP/collagen are augmented in an OCP dose-dependent manner, thereby establishing a suitable composition of this composite as a bone substitute material. OCP/collagens with a wide range of mixing ratios from 23:77 to 83:17, including the previously examined composition (77:23), were prepared by blending granules of OCP with atelocollagen and molded into a disk as an implant. A critical-sized defect was made in rat calvaria, and each disk was implanted into the defect for 4 or 12 weeks and then examined radiographically, histologically, and histomorphometrically. Mouse bone marrow-derived stromal ST-2 cells were cultured in dishes pre-coated with OCP/collagen or OCP alone with different OCP contents to determine the capacity of cell attachment and proliferation up to 14 days. Histological and radiographic examinations showed that newly formed bone was observed in relation to OCP granules within the collagen matrix. Histomorphometric analysis confirmed that increasing the amount of OCP in collagen matrices resulted in progressive enhancement of bone regeneration and that the ratio 83:17 generated the maximum repair level of approximately 64% of the defect at 12 weeks. OCP/collagen promoted the proliferation and attachment of ST-2 cells more than OCP alone regardless of OCP content. Fourier transform infrared spectroscopy analysis of the coatings after the incubation indicated that OCP tended to convert to apatite regardless of the presence of collagen. The present study demonstrated that the osteoconductive characteristics of OCP/collagen can be displayed in an OCP dose-dependent manner. The results suggest that collagen promotes the proliferation and attachment of host osteoblastic cells on OCP/collagen composite implants.
authors.affiliation: Division of Oral Surgery, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kawai
authors.forename: Takahisa
authors.initials: T
authors.lastname: Anada
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Honda
authors.forename: Shinji
authors.initials: S
authors.lastname: Kamakura
authors.forename: Keiko
authors.initials: K
authors.lastname: Matsui
authors.forename: Aritsune
authors.initials: A
authors.lastname: Matsui
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sasaki
authors.forename: Shinji
authors.initials: S
authors.lastname: Morimoto
authors.forename: Seishi
authors.initials: S
authors.lastname: Echigo
authors.forename: Osamu
authors.initials: O
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000737:chemistry*; D002130:Calcium Phosphates / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000494:pharmacology; D003094:Collagen / Q000737:chemistry* / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D017886:Durapatite / Q000737:chemistry; D008297:Male; D051379:Mice; D011859:Radiography; D051381:Rats; D017208:Rats, Wistar; D012887:Skull Fractures / Q000000981:diagnostic imaging; D017550:Spectroscopy, Fourier Transform Infrared; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D013997:Time Factors; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C022045:octacalcium phosphate; D003094:Collagen; D017886:Durapatite