Carboxymethylcellulose-stabilized collagenous rhOP-1 device-a novel carrier biomaterial for the repair of mandibular continuity defects

Human recombinant osteogenic protein-1 (rhOP-1) is osteoinductive. Efforts are made to develop carrier biomaterials with improved space-keeping properties. Bovine collagen type I matrix charged with rhOP-1 was suggested to be an advantageous device of relative liquid quality. We hypothesized that the addition of carboxymethylcellulose (CMC) may stabilize the device and facilitate the regeneration of mandibular continuity defects without further addition of mineralized carrier materials. To test this hypothesis, the anatomical shape, functional remodeling, and mechanical stability of such bony regenerates were evaluated in the course of an animal experiment. Mandibular continuity defects of 5 cm in size were created in five G?ttingen minipigs on one side (contralateral hemimandible: control) and bridged with titanium plates. Four animals were treated with the rhOP-1 device (3000 microg rhOP-1, 2 g collagen, 1 g CMC), and one animal was treated with a placebo device omitting rhOP-1. After 12 weeks of experimental period, bony continuity was reestablished in rhOP-1-treated hemimandibles. The bony regenerates were of good anatomical shape, volume, and functional remodeling. Placebo treatment led to insufficient bony regenerates of significant lower bone volume (volume in 3D-CT scan 29.81 cm(3) vs 8.85 cm(3)). To produce 1 mm of bending, 1972 N were needed for rhOP-1-treated hemimandibles, 2617 N for control hemimandibles, and 642 N for the placebo treated hemimandible. CMC stabilization of collagen carrier biomaterials for rhOP-1 provides good plasticity as well as excellent space-keeping properties and may not interfere with osteoinduction. The results of this preliminary study suggest that the applied rhOP-1 device offers a potential option for further studies on the reconstruction of mandibular defects.