Effect of recombinant human osteogenic protein-1 on the healing of a freshly closed diaphyseal fracture.
Osteogenic protein-1 (OP-1), or bone morphogenetic protein-7, is an osteoinductive morphogen that is involved in embryonic skeletogenesis and in bone repair. In bone defect models without spontaneous healing, local administration of recombinant human OP-1 (rhOP-1) induces complete healing. To investigate the ability of rhOP-1 to accelerate normal physiologic fracture healing, an experimental study was performed. In 40 adult female goats a closed tibial fracture was made, stabilized with an external fixator, and treated as follows: (1) no injection; (2) injection of 1 mg rhOP-1 dissolved in aqueous buffer; (3) injection of collagen matrix; and (4) injection of 1 mg rhOP-1 bound to collagen matrix. The test substances were injected in the fracture gap under fluoroscopic control. At 2 and 4 weeks, fracture healing was evaluated with radiographs, three-dimensional computed tomography (CT), dual-energy X-ray absorptiometry, biomechanical tests, and histology. At 2 weeks, callus diameter, callus volume, and bone mineral content at the fracture site were significantly increased in both rhOP-1 groups compared with the no-injection group. As signs of accelerated callus maturation, bending and torsional stiffness were higher and bony bridging of the fracture gap was observed more often in the group with rhOP-1 dissolved in aqueous buffer than in uninjected fractures. Treatment with rhOP-1 plus collagen matrix did not result in improved biomechanical properties or bony bridging of the fracture gap at 2 weeks. At 4 weeks there were no differences between groups, except for a larger callus volume in the rhOP-1 plus collagen matrix group compared with the control groups. All fractures showed an advanced stage of healing at 4 weeks. In conclusion, the healing of a closed fracture in a goat model can be accelerated by a single local administration of rhOP-1. The use of a carrier material does not seem to be crucial in this application of rhOP-1.
den Boer
F C
FC
Department of Surgery, VU University Medical Centre, Amsterdam, The Netherlands. frankdenboer@hotmail.com
Bramer
J A M
JA
Blokhuis
T J
TJ
Van Soest
E J
EJ
Jenner
J M G T
JM
Patka
P
P
Bakker
F C
FC
Burger
E H
EH
Haarman
H J T M
HJ
D015502:Absorptiometry, Photon / Q000379:methods; D000818:Animals; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000627:therapeutic use*; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000293:injuries; D005260:Female; D006041:Goats; D006801:Humans; D011994:Recombinant Proteins / Q000627:therapeutic use*; D013978:Tibial Fractures / Q000000981:diagnostic imaging / Q000188:drug therapy*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016212:Transforming Growth Factor beta
C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta