High yield of osteoinductivity can be derived from demineralized bone matrix using collagenase digestion

A bone morphogenetic protein purification method for minor quantities of bone material was developed based on collagenase splitting of bone connective tissue. Our aim was to remove and characterize the osteoinductive protein preparation in native form without using strongly dissociative agents. We started from 80 g of HCl-demineralized reindeer bone material which was treated with type I collagen splitting collagenase. The solution was dialyzed against 10 mM glycine-HCl buffer, pH 5.2. The formed precipitate was found to be osteoinductive. After fractionation of the material using HPLC gel filtration it was observed that the high-molecular-weight component of the precipitate was biologically active. Isoelectric focusing revealed that the component consisted of at least eight different protein molecules. Lower-molecular-weight components induced no bone formation. These preliminary findings suggest that in native form at least one part of BMP is in a complex form and other extracellular matrix components bound to the osteoinductive protein complex are significant for BMP action and may act synergistically or as carriers for the BMP.