Ability of deproteinized cancellous bovine bone to induce new bone formation

Background: Preclinical and clinical studies indicate that deproteinized ca ncellous bovine bone is osteoconductive and may be osteopromotive. Previous studies using commercial preparations failed to demonstrate the presence o f protein, implicating bone-mineral composition and 3-dimensional structure as reasons for clinical success; however, these studies did not examine wh ether osteoinductive factors might be present in close association with the mineral phase. Methods: Deproteinized cancellous bovine bone was decalcified and any prote in present released by chaotropic solvents using the protocol described for purification of bone morphogenetic proteins (BMPs). Three extracts were ob tained and tested for their ability to support osteoinduction in the calf m uscle of nude mice. Results: Protein content averaged 11 mug/g based on absorbance at 280 nm us ing bovine serum albumin as a standard. All extracts contained material tha t stained positively with silver stain after sodium dodecyl sulfate polyacr ylamide gel electrophoresis (SDS PAGE). Western blots of these gels indicat ed the presence of transforming growth factor-beta (TGF-beta) and BMP-2, Al l 3 extracts were osteoinductive in the nude mouse model when combined with inactive DFDBA, and bone formation was comparable to that induced by activ e DFDBA, Deproteinized cancellous bovine bone by itself was not osteoinduct ive in the nude mouse, but in a clinical case, exhibited osteoclastic resor ption with adjacent new bone formation. Conclusions: The results suggest that small amounts of protein are present in deproteinized cancellous bovine bone in close association with the miner al phase, Some of the extracted material has osteoinductive potential and m ay contain growth factors, This may explain the osteopromotive ability of d eproteinized cancellous bovine bone clinically.