Biomechanical Response of Macrophages/Microglia Cells to Blast Shock Injury in Mice / 医用生物力学

ABSTRACT

Objective To establish a blast injury experimental model using a shock tube at lateral lying position of C57BL/6 mice, investigate biomechanical responses of macrophages/microglia cells in the heart, lung and brain tissues to mechanical damage by shock wave within 24 hours. Methods Shock tube was employed to generate a shock wave to C57BL/6 mice. Firstly, the weight changes of mice were measured at different time points after the shock. Then the cardiac, pulmonary and whole brain tissue samples were dissected after anesthesia. Pathological sections were stained with HE staining to detect structural damage; the TUNEL staining method was used to mark and count the proportion of dead cells in each tissue. Microglial cells were labeled with fluorescent antibody, while responses and changes of macrophages/microglia after shock loading were analyzed. Results The shock tube exerted 179 kPa overpressure shock wave upon sideway of the mouse, and lethal rate of the mouse was 3.33%. Compared with normal control group, the mice in experimental group had a significant weight loss within 24 hours after loading shock. Pathological sections showed rupture of lung tissues after shock, accompanied by alveolar protein deposition, pulmonary bulla and other diseases. Fluorescence staining showed that lung tissue was recruited and activated in a large amount within 24 hours. The proportion of dead cells cleared rebounded to normal level within 24 hours. The heart was highly tolerant to shock, and macrophages appeared near the large blood vessels. The brain showed unilateral aggregation of microglia due to the impact posture, mainly due to prolonged inflammation and a higher proportion of dead cells at the junction of gray and white matter. Conclusions A blast shock model at lateral lying position of the mouse was established. Within 24 hours, macrophages/microglia were recruited quickly to the injury site after being impacted, which mediated strong immune stress, and might participate in the immune response to trigger a second long-term inflammatory injury. The results of the study provide experimental basis for the evaluation of primary impact injury, such as dose-effect relationship and tissue damage difference.