title: Characterization of radioiodinated recombinant human TGF-beta 1 binding to bone matrix within rabbit skull defects.
abstract: Bone healing is regulated in part by the local production of TGF-beta 1 and other growth factors produced by cells at the site of injury. The single application of recombinant human TGF-beta 1 (rhTGF-beta 1) to calvarial defects in rabbits induces an accelerated recruitment and proliferation of osteoblasts within 3 days. This ultimately results in the formation of new bone and the complete closure of the defect within 28 days. The persistence and localization of [125I]rhTGF-beta 1 within an osseous defect was investigated after applying a single dose of [125I]rhTGF-beta 1 formulated in a 3% methylcellulose vehicle. Normal bone encompassing the defect site, the periosteum, and the gel film covering the dura were harvested at 0, 4, 8, and 24 h and 3, 7, and 16 days after [125I]rhTGF-beta 1 application. The defect site-associated radioactivity was quantitated, visualized by autoradiography, and characterized by TCA precipitation and SDS-PAGE. Radioactivity was observed in autoradiographs of gross specimens, histologic sections of the bone matrix, and periosteal tissue surrounding the defect. There was a time-dependent decrease in TCA-precipitable radioactivity; however, radioactivity was still associated with the bone matrix 16 days after application of [125I]rhTGF-beta 1. SDS-PAGE and autoradiography of the radioactivity in homogenized bone and periosteal samples revealed a 25 kD band, suggesting that the radioactivity remaining at the defect site represented intact [125I]rhTGF-beta 1.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Safety Evaluation, Genentech, Inc., South San Francisco, California.
authors.forename: L
authors.initials: L
authors.lastname: Richardson
authors.forename: T F
authors.initials: TF
authors.lastname: Zioncheck
authors.forename: E P
authors.initials: EP
authors.lastname: Amento
authors.forename: L
authors.initials: L
authors.lastname: Deguzman
authors.forename: W P
authors.initials: WP
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: L S
authors.initials: LS
authors.lastname: Beck
mesh_terms: D000818:Animals; D017102:Fracture Healing / Q000187:drug effects*; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D011817:Rabbits; D012886:Skull / Q000293:injuries / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D007457:Iodine Radioisotopes; D016212:Transforming Growth Factor beta