Different storage times and their effect on the bending load to failure testing of murine bone tissue

Cryopreservation is a well-established method for bone storage. However, the ideal timing of mechanical testing after sacrificing the experimental animals is still under discussion and of significant importance to the presentation of accurate results. Therefore, the aim of this study was to investigate and compare different cryopreservation durations to native murine bone and whether there was an influence on mechanical bone testing. For this study the tibias of 57 female C57BL/6 mice-18-weeks of age-were harvested and randomly allocated to one of four groups with varying storage times: (1) frozen at -80 °C for 3 months, (2) frozen at -80 °C for 6 months, (3) frozen at -80 °C for 12 months and (4) native group. The native group was immediately tested after harvesting. The comparison of the mean strength and load to failure rates demonstrated a significant difference between the storage groups compared to the native control (p = 0.007). However, there was no difference in the strength and the load to failure values of bones of all storage groups when compared against each other. Once cryopreservation at -80 °C is performed, no differences of mechanical bone properties are seen up to 12 months of storage. When actual in vivo data is of close interest, immediate testing should be considered and is preferred. If comparison of groups is required and long-time storage is necessary, cryopreservation seems to be an accurate method at present.