The osteoinductive activity of bone morphogenetic protein (BMP) purified by repeated extracts of bovine bone.

Native bone morphogenetic proteins (BMPs) extracted from bone have been used clinically to stimulate bone regeneration and repair. However, preparation of purified BMP is a laborious process. This study investigated the yield, activity and cost effectiveness of repeatedly extracting the same bone matrix to produce purified BMP. While repeated extraction was able to increase the yield 62% the activity of the partially purified BMP in later extracts decreased both in vitro and in vivo. This decline in activity appears to be due to an increase in non-BMP contaminants, such as collagen, in the extracts. When the first three extracts were combined and processed together activity was equivalent to that of the first extract. A simple analysis based on the cost of reagents used and the time required for purification indicates that separate processing of the extracts is inefficient while combining the first and second extracts and processing them together would result in a small cost saving. Based on this study we would recommend that the demineralized bone matrix be extracted no more than twice and that the extracts be combined for further processing.