Study On The Relationship Between AQP4 Expression And Muscle Edema After Blast Injury

The rate of blast injuries in modern warfare has increased rapidly, and the condition of the injuries are more serious than before. Soft tissue injury is the most common type in blast injury. How to reduce soft tissue injury is a high priority area for military medical researchers. The damage by explosives is not localization for body. There is a medial area between necrotic tissue and normal tissue. Their range is uncertain and relies on the quantity of necrotic cells. More tissue could be saved by breaking down the pathological cause "edema-necrosis -infection". It could provide a great foundation for tissue regeneration. Big area Tissue edema was observed in the medial area. The physiological role of tissue in the medial area could result in restoration if the tissue edema was gone rapidly. For this reason, this study is based on the pig soft tissue blast injury model and observing the course of soft tissue edema, and the discussion of the mechanism of NPWT(negative pressure wound therapy, NPWT).Part 1 Establishment of an animal model for explosive soft tissue defects in pigsObjective:To establish an animal model for explosive tissue defects under laboratory conditions.Method:There were ten small domestic pigs for experimental animals. Wounds are located 4cm behind the anterior superior iliac spin and 10cm to the dorsal above the shoulder joint. Instantaneous electric detonators were used in the experiment. The area and depth of tissue injury was compared.Result:Effects of the shock wave on every position were nearly the same. No difference was found in the peak value positive, duration of positive pressure and rise time of pressure. The wound shape was almost round and the wound edge was not regular. The soft tissue in the wound center was absolutely injured. There was a lot of foreign matter in the surface of the wound. The average size of soft tissue defects after the debridement was (47.11±3.70)cm2 and the depth is (1.18±0.36cm). Both the area and depth were not found to be statistical different for each wound.Summary:The animal experiment model is suitable for study of soft tissue defects reconstruction, characterized by good repeatability, stability, uniform wound areas and defect depth. Part 2 The relationship between AQP4 expression and soft tissue edema after blast injuryObjective:To investigate the change of aquaporin-4(AQP4) expression after traumatic soft tissue injury in pigs, and its correlation with the intramuscular edema.Methods:The animal model for explosive soft tissue defects in pigs was used. Ten pigs were divided into 2 groups randomly, the controll group and the experimental group. The muscle water content (MWC) was measured by dry-wet weight methods. The Immunohistochemistry (IHC) was used to located the position of the AQP4 expression. AQP4 protein changes of the injury software were measured by Western-Blot. Reverse transcriptase PCR (RT-PCR) was used to detect the changes of the AQP4 mRNA.Result:The expression of AQP4 was located in the membrane of skeletal muscle cells in both groups. The expression of AQP4 significantly increased at 6 hours after blast injury. The MWC and the expression of AQP4 and AQP4 mRNA were different at 6 hours, 3 days,5 days and 7 days compared with the controll group (p<0.05). The MWC and the expression of AQP4 and AQP4 mRNA have theirs peak at 3 days, then decreased with the duration of time.Summary:The expression aqp4 was strongly increased after injury. At the same time, the muscle edema was greatly improved. The result implies that the AQP4 may participate the muscle edema reaction after blast injury.Part 3 The effect of relieving soft tissue edema in explosive soft tissue wounds with the early application of NPWTObjective:To observe the effect of early NPWT application on relieve soft tissue edema and discuss the relationship between NPWT and AQP4.Methods:The animal model for explosive soft tissue defects in pigs was used. Ten pigs were divided into 2 groups randomly, the NPWT group and the classical group. The muscle water content (MWC) was measured by dry-wet weight methods. The Immunohistochemistry (IHC) was used to located the position of the AQP4 expression. AQP4 protein changes of the injury software were measured by Western-Blot. Reverse transcriptase PCR (RT-PCR) was used to detect the changes of the AQP4 mRNA.Result:The expression of AQP4 was located in the membrane of skeletal muscle cells in both groups. In NPWT group the MWC and the expression of AQP4 and AQP4 mRNA were different at 6 hours,3days,5 days and 7 days compared with the classical group (p<0.05). The MWC and the expression of AQP4 and AQP4 mRNA have theirs peak at 3 days, then decreased with the duration of time in both groups.Summary:The muscle edema was greatly relieved by NPWT. At the same time, the expression aqp4 was greatly reduced. The result implies that the application of NPWT could relieve the edema of soft tissue, and the the AQP4 may participate the muscle edema reaction by NPWT.