title: Stimulation of bone formation with an in situ setting tricalcium phosphate/rhBMP-2 composite in rats.
abstract: The aim of the study was to determine bone-regenerative effects of an in situ setting tricalcium phosphate (TCP) cement combined with rhBMP-2 and to compare it with autologous bone graft. A trepanation defect of 1.5 mm in the femur diaphysis of Sprague-Dawley rats was filled with an in situ setting TCP cement combined with 0, 0.25, 2.5, or 25 microg of rhBMP-2, an autologous bone graft, or left empty. The rats were euthanized after 1 and 3 weeks and examined by radiography, histology, histomorphometry, and bending tests. All TCP groups with or without BMP-2 showed a good bony ingrowth with a close bone-cement contact. Histomorphometric analysis showed no increase of new bone formation in the defect, but a dose-dependent increase in callus formation with a maximum at 25 microg of rhBMP-2. As shown with intravital fluorochrome staining, new bone formation started earlier using rhBMP-2. Bone strength, measured in a three-point bending test and expressed in percentage of the contralateral healthy femur, was 75% for TCP + 25 microg rhBMP-2, 44% for TCP + 2.5 microg rhBMP-2, and 34% for autologous bone graft. TCP particles were detectable in all groups after 3 weeks. Callus formation and bending strength of the TCP + 25 microg rhBMP-2 group was superior to autologous bone graft. So TCP/rhBMP-2 composites may prove to be an effective substitute for autologous bone grafts.
authors.affiliation: Department of Orthopedic Surgery, University of Aachen, Pauwelsstrasse 30, D-52074 Aachen, Germany. cniedhart@gmx.de
authors.forename: Christopher
authors.initials: C
authors.lastname: Niedhart
authors.forename: Uwe
authors.initials: U
authors.lastname: Maus
authors.forename: Eva
authors.initials: E
authors.lastname: Redmann
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt-Rohlfing
authors.forename: Fritz U
authors.initials: FU
authors.lastname: Niethard
authors.forename: Christian H
authors.initials: CH
authors.lastname: Siebert
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects*; D002130:Calcium Phosphates / Q000494:pharmacology*; D004396:Coloring Agents; D004305:Dose-Response Relationship, Drug; D005269:Femur / Q000033:anatomy & histology / Q000254:growth & development; D005456:Fluorescent Dyes; D008297:Male; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D014048:Tolonium Chloride; D016212:Transforming Growth Factor beta
chemical_list: C525720:Bmp2 protein, rat; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D002130:Calcium Phosphates; D004396:Coloring Agents; D005456:Fluorescent Dyes; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C485817:beta-tricalcium phosphate; D014048:Tolonium Chloride; C018392:tricalcium phosphate