Study on mass transfer in the bone lacunar-canalicular system under different gravity fields.

INTRODUCTION: The bone lacunar-canalicular system (LCS) is an important microstructural basis for signaling and material transport in bone tissue, guaranteeing normal physiological processes in tissues. Spaceflight astronauts and elderly osteoporosis are related to its function, so it is necessary to reveal the mass transfer laws in bone microstructure under different gravity fields to provide insight for effective clinical treatment.

MATERIALS AND METHODS: Using the natural LCS structure of bovine tibial cortical bone as the object, the mass transfer experiments on cortical bone were conducted by using sodium fluorescein tracer through different frequency pulsating pressure provided by dynamic perfusion loading device and different high G environments provided by high-speed centrifuge to analyze the mass transfer laws under different gravity fields and different pulsating pressures.

RESULTS: The fluorescence intensity of lacunae within the osteon was lower the farther away from the Haversian canal. As the gravity field magnitude increased, the fluorescence intensity within each lacuna enhanced, and the more distant the lacunae from the Haversian canal, the greater the fluorescence intensity enhancement. High-frequency pulsating pressure simulated high-intensity exercise in humans can improve mass transfer efficiency in the LCS.

CONCLUSION: High-intensity exercise may greatly increase solute molecules, nutrients, and signaling molecules in osteocytes and improve the activity of osteocytes. Hypergravity can enhance the transport of solute molecules, nutrients, and signaling molecules in the LCS, especially promoting mass transfer to deep layer lacunae. Conversely, mass transfer to deep layer lacunae may be inhibited under microgravity, causing bone loss and ultimately leading to osteoporosis.