title: Evaluation by bone scintigraphy of osteogenic activity of commercial bioceramics (porous beta-TCP and HAp particles) subcutaneously implanted in rats.
abstract: Osteogenic potential of biomaterials used in bone regenerative therapy has been mainly examined in an animal-implantation study. We have here evaluated the applicability of bone scintigraphy in imaging ectopic bone formation, especially its initial phase, by beta-tricalcium phosphate (beta-TCP) particles that were implanted in rat dorsal subcutaneous tissues. In implanted osteogenic osteosarcoma cells used as a positive control, osteoid formation was found by histological examination and bone scintigraphy using (99m)Tc- hydroxymethyl diphosphonate (HMDP) at 2 and 3 weeks post-implantation, respectively, while the microfocuscomputed tomography (muCT) system required further mineralization, which occurred at 4 weeks. Implantation of beta-TCP particles alone induced only faint biomineralization inside the particles, which could be microscopically detected by calcein chelation at 2 weeks post-implantation, but not by other histological examinations (e.g., HE staining) or muCT. However, the bone scintigraphy successfully detected this microscopic change at 1 week. Implanted hydroxyapatite (HAp) particles alone used as a negative control did not induce mineralization at microscopic levels, and therefore nothing was detected by either calcein chelation or bone scintigraphy. In conclusion, the bone scintigraphic methodology, although exhibiting less quantitation and resolution, would be applicable as a non-invasive, highly sensitive methodology in detecting the initial, microscopic changes associated with mineralization.
authors.affiliation: Division of Oral Bioengineering, Department of Tissue Regeneration and Reconstitution, Institute of Medicine and Dentistry, Niigata University, Niigata 951-8514, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakayama
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kawase
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kogami
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Okuda
authors.forename: Hikaru
authors.initials: H
authors.lastname: Inoue
authors.forename: Takaaki
authors.initials: T
authors.lastname: Oda
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Hayama
authors.forename: Makoto
authors.initials: M
authors.lastname: Tsuchimochi
authors.forename: Larry F
authors.initials: LF
authors.lastname: Wolff
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002130:Calcium Phosphates / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D006882:Hydroxyapatites / Q000008:administration & dosage*; D008297:Male; D011877:Radionuclide Imaging / Q000379:methods*; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002130:Calcium Phosphates; D006882:Hydroxyapatites; C485817:beta-tricalcium phosphate