[Reconstitution of osteoinductive bone xenograft: bioassay in mice]

How to eliminate the antigenicity of bone xenograft while retaining its osteoinductive activities is an unsolved problem in the orthopaedic field. This paper reports an encouraging approach to the question by the following procedures extracting the bone morphogenetic protein (BMP) from cortical bone; eliminating the antigenicity of cancellous bone by chemical extraction; and reconstituting the graft with the treated cancellous bone serving as a delivery medium for BMP. This composite graft is accepted immunologically, and is also osteoinductive in the heterogenous host. In point of delivery medium of BMP, the cancellous bone xenograft is the best choice due to its abundant sources. Bioassay in mouse showed that the reconstituted graft, including only 0.5 mg BMP, demonstrated a definitive osteoinductive ability. In addition, this paper first furnished the information that the BMP aggregate from chemical extraction as described in the literature is also antigenic in the heterogenous host.