COMMERCIALLY-PREPARED ALLOGRAFT MATERIAL HAS BIOLOGICAL-ACTIVITY IN-VITRO

THE WELL-ESTABLISHED FINDING that implantation of demineralized bone m atrix at non-skeletal sites results in formation of cartilage and bone has been attributed to bone morphogenetic proteins/factors. Commercia lly-available demineralized bone allograft materials are being used cu rrently to reconstruct/regenerate bone. The studies described here foc used on establishing biological activity of protein extracts prepared from commercially obtained bone graft material in vitro. Furthermore, the biological activity of these protein extracts in vitro was compare d with similar extracts prepared from freshly obtained human bone. Bio logical activities of bone matrix proteins examined included their abi lity to promote proliferation, attachment, and migration of gingival f ibroblasts using an in vitro system. Guanidine followed by guanidine/E DTA was used to separate bone matrix proteins into proteins associated with soft tissues of bone and proteins retained within the mineral co mpartment, respectively. Two preparations of each starting material we re tested and the biological activity of each preparation was evaluate d in triplicate at least three times. Slot blot analysis revealed that commercially-prepared material contained type I collagen; fibronectin ; BSP; and BMP-2, 4, and 7. However, the freshly prepared bone extract s appeared to have higher BMP concentrations. The ability of commercia l extracts to promote cell proliferation, while significant, was limit ed and significantly less when compared with similar extracts prepared from freshly obtained bone. All extracts promoted cell attachment sig nificantly, while none of the extracts promoted cell migration. Thus, commercially-prepared material retained proteins having the capacity t o influence cell behavior in vivo. However, some biological activity a s measured in vitro was lost as a result of tissue processing.