A loading device suitable for studying mechanical response of bone cells in hard scaffolds

Bone cells live in an environment heavily influenced by mechanical forces. Systematic study of cell's mechanical responses has relied greatly on the in-vitro experiments due to complexity of internal environment of bone cells in vivo. A loading device suitable to hard scaffolds for studying mechanical responses of bone cells was made by using a kind of long-travel, high-load piezoelectric actuator. The device, which was precisely controlled by computer, and designed to work in an incubator at 37 degrees C and 100% humidity, can cause hard scaffolds with directly compressive strains with more magnitudes, frequency components, and waveforms, including bone physiologically mechanical state. The experiment using hard scaffolds indicates the device validity. The device represents a versatile model that will provide conditions for investigating the effects of mechanical responses on bone cells in 3D hard scaffolds in vitro. In addition, the preliminary biological test was performed by the application of the device. The results showed that the dynamic compression with the amplitude of 1000 microstrain, the frequency of 3 Hz, the duration of 3 min/day enhanced the osteoblastic proliferation and extracellular matrix compared with static conditions, and improved the cell distribution within scaffolds. The researches of 3D mechanical effects on bone cells just in hard scaffolds similar to that in cancellous bone can enhance the understanding of bone physiology in vivo. The direct, dynamic contact-loading of the device may provide an appropriate mechanical condition in bone tissue engineering culture.