Control study between behavioral and pathological findings of the transected spinal cord model in rats / 中国组织工程研究

ABSTRACT

BACKGROUND:Ideal models of spinal cord injury should simulate human spinal cord injury, exclude confounding factors affecting effects, and have extensive repeatability. Spinal cord transection model is an ideal choice at present. Nevertheless, the operation is diverse, so therapeutic effects have great differences, and the research results lack of comparability. OBJECTIVE:To compare and analyze behavioral changes and pathological features of rat hindlimb after spinal cord transection by establishing standardized model of transected spinal cord in rats. METHODS:A total of 60 adult female Sprague-Dawley rats were randomly divided into sham surgery group (n=12), conventional spinal cord transection group (n=24) and microscopic spinal cord transection group (n=24). Each group was randomly assigned to 7-day, 14-day and 28-day groups according to time points after model establishment. T9 vertebrae were considered as a center. Sham surgery group underwent laminectomy. Other groups underwent spinal cord transection. Thus, models of acute spinal cord injury were induced. Models in the conventional spinal cord transection group were established by conventional surgical methods. Models in the microscopic spinal cord transection group were established by standardization micromanipulation technique. At 7, 14 and 28 days after model establishment, motor function of hindlimb was evaluated using Basso, Beattie and Bresnahan (BBB) scoring system. Histopathology of transected spinal cord was observed. The thickness of the glial scar, the longitudinal distance between the two stumps, the transverse diameter of the spinal cord cavity and cerebrospinal fluid cyst formation were measured at the transected site of the spinal cord. RESULTS AND CONCLUSION:In the sham surgery group, preoperative and postoperative BBB scores and pathology of the spinal cord did not clearly change. In the conventional spinal cord transection group and microscopic spinal cord transection group, complete paralysis of hindlimb was detected after model establishment. Hindlimb function did not recover in the conventional spinal cord transection group. At 1 to 2 weeks after model induction, spontaneous recovery of hindlimb function was visible in rats of the microscopic spinal cord transection group. Spinal pathology index value was significantly lower in the microscopic spinal cord transection group than in the conventional spinal cord transection group (P<0.01). Pathological observations were not correlated with BBB scores in each group. These data indicated that standardized spinal cord transection method helps to eliminate individual differences and to quantitatively analyze and to compare studies addressing therapeutic effects.