Synthetic polymers as carriers for osteogenic proteins

Recombinant human osteogenic protein-1 (OP-1) was combined with a series of nonproteinaceous polymeric carriers in varying dosages. The implants were placed in critical sized bilateral ulnar segmental defects of thirty rabbits and twelve dogs. Animals were followed radiographically every two weeks to evaluate the rate and amount of bone formation. Rabbits were sacrificed at eight weeks and dogs were sacrificed at twelve weeks postimplantation. Post-sacrifice mechanical testing and histologic analysis was performed on the retrieved specimens. Sequential radiographs demonstrated new bone formation in all OP-1/polymer sites. The healed polymeric/OP-1 defects demonstrated torsional strength approaching intact controls and OP-1/collagen. This investigation demonstrates that polymeric carriers with the appropriate dosage and degradation characteristics may be used to deliver OP-1 to heal large segmental bone defects