Prefabrication of vascularized bone grafts using recombinant human osteogenic protein-1 - part 3: dosage of rhOP-1, the use of external and internal scaffolds

In a previous study vascularized bone grafts were prefabricated with recombinant human osteogenic protein-1 (rhOP-1) using blocks of xenogenic bone mineral (BioOss((R))) as scaffolds. The present study addressed the dosage of rhOP-1 and the combination of an external (mould) and internal scaffold (granular BioOss((R))). In five Gottingen minipigs six prefabrication sites in the latissimus dorsi muscles were randomly assigned to groups a-f. Moulds were prepared by shaping collagen/polylactide membranes in a cylindrical form which was filled with 1 g BioOss((R)) granules and rhOP-1 (a: 0; b: 50; c, f, e: 250; d: 1000 mug of rhOP-1, a-e: cylinder open to muscle, e cylinder perforated, f. cylinder open to subcutaneous fat). After 6 weeks a dose dependency of bone density (a-d: 0%; 9.4%; 15.8%; 31.1%) and vessel density (a-d: 0.3; 2.4; 7.9; 25.4 counts/view) was observed histomorphometrically. Muscular surrounding was advantageous to subcutaneous tissue. Perforations of the membranes increased vessel density and did not impair bone formation. Bone density decreased in the proximity of the polylactide membranes. The membrane material was too soft and partly collapsed and Key words: bone morphogenetic proteins; therefore needs not to be reconsidered. The use of BioOss((R)) granules with 1000mug mandibular reconstruction; surgical flaps. rhOP-1 per gram proved to be a suitable concept for prefabrication of bone transplants.