Bone extract from reindeer induces new ectopic bone formation (BF) in muscle pouches, but its feasibility in experimental bone lesions has not been evaluated. We investigated the effects of implants, containing 2, 5, 15, 20 or 50 mg of reindeer bone extract in a collagen carrier, on the healing of 8-mm femur defects in 78 rats. We used 30 µg of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a collagen carrier, collagen and untreated defects as controls. Bone healing was evaluated with radiographs, peripheral quantitative computed tomography (pQCT), biomechanics and histology. In comparison with empty defects, the groups receiving bone extracts showed more BF at three weeks and had better bone union (BU), larger mean cross-sectional bone area at the defect site in groups receiving higher doses of extract, showed greater torsional stiffness of the bones and higher maximum breaking load of bones at six weeks. In comparison to all other groups, in the rhBMP-2 group, BF and BU were best at the three-and six-week follow-up, bone area was largest and mechanical test results were best. Although rhBMP-2 is superior for new bone regeneration, native reindeer bone extract is also effective in the six-week follow-up period.

Bioactive glasses have been developed as scaffolds for bone tissue engineering but combination with reindeer bone protein extract has not been evaluated. We investigated the effects of bone protein extract implants (5-40 mg dosages) with bioglass (BG) carrier on the healing of rat femur defects. Bioglass implants and untreated defects served as controls. All doses of extract increased bone formation compared with the control groups, and bone union was enhanced with doses of 10 mg or more. In comparison with untreated defect, mean cross-sectional bone area at the defect site was greater when implants with BG + 15 mg of extract or bioglass alone were used, bone density at the defect site was higher in all bioglass groups with and without bone extract, and the BG + 15 mg extract dosage marginally increased bone torsional stiffness in mechanical testing. Bioglass performed well as a carrier candidate for reindeer bone protein extract.

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Various bone proteins and growth factors in specific concentrations are required for bone formation. If the body cannot produce sufficient quantities of these factors, bone trauma can be healed with an implant that includes the required factors in a carrier. This study was designed to evaluate various calcium salt candidates that can be used as carrier with reindeer bone protein extract to induce ectopic bone formation in the muscle pouch model of mouse. The bone protein extract was either impregnated into the disc form of carrier or mixed with carrier powder before implantation. The radiographic analysis indicated increased bone formation in all of the active groups containing the bone protein extract compared to the controls within 21 days follow-up. The highest bone formation was seen in the group with calcium sulfate with stearic acid where new bone and calcified cartilage were clearly visible. The greatest bone formation occurred in the groups that had bone protein extract readily available. This indicates that the bone forming factors in sufficient concentrations are required at the early stage of bone formation. The calcium sulfate with stearic acid was the most suitable and effective carrier for reindeer bone protein extract.