The influence of sterilization on the osteoinductive properties of bone in rat bone marrow cell culture

Bone allografting is useful in the reconstruction of defects or supplementation of bone required during the treatment of bone tumors or comminuted fractures. Gamma-irradiation or heat-treatment at 60degC for 10 h or 80degC for 10 min are recognized procedures for the sterilization of bone before grafting. We investigated the ability of sterilized bone to induce proliferation in rat bone marrow cell cultures, and to induce alkaline phosphatase (ALP) activity in the cells. Addition of irradiated bone resulted in increased numbers of bone marrow cells and ALP activity in such cultures. However, larger doses of radiation to the bones suppressed this cell proliferation-inducing activity, whereas induction of ALP activity was not depressed by higher radiation doses. When the inducing activity was compared after the various sterilization processes, processed bones increased the cell number in culture by 45 percent and 35 percent compared with controls on days 7 and 14, respectively, despite sterilization. ALP activity was also increased by the processed bones (37 percent and 9 percent compared with controls on days 7 and 14, respectively), and this was again independent of the sterilization method employed. These results indicate that osteoinductive activity is retained after sterilization by either of the common methods employed. (author)