Local Fractionated X-ray Irradiation Combined With GM-1 Injection In The Therapy Of Rats With Spinal Cord Injury

Part I Establishment of spinal cord injury model in ratsIntroduction:Much animal models of spinal cord injury(SCI) are used to study the treatment of SCI. Following Allen’s method,we can make animal SCI model with different degree of damage,and the mechanism of injury is more close to clinical.So Allen method has been widely used. However, most of the equipment used for Allen’s method is too complex and not suitable for widely use.Objective:To design and manufacture a reformed simplified SCI model by Allen’s weight dropping.Methods: Design and manufacture the impact device for injuring spinal cord in rats. Female Sprague-Dawley(SD) rats in a total of 70,given a crush energy of 150 gcf on the spinal cord of the T11-12 segment according to the Allen’s method.In order to know the degree of spinal cord injury and observe the recovery of neurological function of the animal,the physical condition of all the experimental animals was observed, the motor function evaluation of the hind limbs,somatosensory evoked potential and histological examination were performed.Results: There was no significant difference in the color of hair and the diet status of the experimental animals before and after SCI. One day after surgery, one animal died of systemic failure due to loss of blood,and 2 of them died of urinary infection after 2 weeks. Postoperative 2W total of Four rats’ BBB score of the hind limb were over 8 points, the rest animals are below 4 points. HE staining showed that the structure of the spinal cord was damaged in the rats after SCI operation, and the cavity was formed in some areas. The final model’s success rate was 90%.Conclusion: The impact device which we designed and manufactured is simple, economical and practical. Allen’s weight dropping method has many obvious advantages which is worth to be widely used.Part II The study of local X-ray irradiation in the treatment of spinal cord injury in rats.Introduction: Recent studies have shown that X-ray irradiation can improve the micro environment of injured spinal cord which is proper to the regeneration of rat spinal central system and then promoting the recovery of the function in rats. Our previous studies also demonstrated that 10 Gy and 20 Gy X-ray irradiation can promote the repair of the injured spinal cord tissue.However, a single dose is too large which may bring certain radiation damage. So, this study using fractionated irradiation method which is similar to tumor radiation therapy on a rat model of spinal cord injury.Objective: To investigate the effect of fractionated irradiation on spinal cord injury in a rat model.Methods: 70 female Sprague-Dawley rats with spinal cord injury on the segment of T11-12 by Allen’s weight droppin were randomly divided into four groups: blank control group(10 rats), SCI group(20 rats), SCI+20Gy single irradiation group(n = 20), the SCI + fractionated irradiation group(n = 20); The irradiation group were given irradiation on 2 weeks after SCI by medical linear accelerator.Blank group and SCI group were not irradiated. Each group of experimental animal were euthanized at 6 weeks after SCI.The BBB score, somatosensory evoked potentials and histological examination were received during the experiment proceeding.Results: 6 rats were dead due to various reasons at the end of the experiment.The BBB score was increased from(1.3±0.3)to(3.1±0.5)in SCI group,increased from(1.4±0.3)to(7.2±0.6)in SCI+single irradiation group,increased from(1.3±0.4)to(6.9±0.7)in SCI+fractionated irradiation group. The SEP results showed that the latency period of SCI group was longer than that SCI+irradiation groups(P<0.05);the count of NF was(20.5±3.4)in SCI group,was(67.6±5.9)in SCI+single irradiation group,was(71.2±5.3)in SCI+fractionated irradiation group; the count of MBP was(273.4±12.5)in SCI group,was( 202.8±13.1) inSCI+single irradiation group,was( 198.4±11.7) in SCI+fractionated irradiation group.(P<0.05);the count of GFAP in irradiation group was much less than control group(P<0.05).Conclusion: A proper dose of X-ray irradiation can reduce the formation of glial scar in injured spinal cord area of rats, which promotes the recovery of the nerve function after spinal cord injury in rats. A single irradiation and the fractionated irradiation may reach the same radiation effect.Part III Local fractionated X-ray irradiation combined with GM-1 injection in the therapy of rats with spinal cord injury.Introduction: The studies showed that a certain dose of X-ray irradiation could promote the recovery of spinal cord injury in rats. The possible mechanism of the radiation intervention was considered to inhibit the formation of glial scar and improve the microenvironment of spinal cord injury. This part combines the fractionated X-ray irradiation with ganglioside(GM-1) injection, intent on inhibition of inhibiting factors in repair of spinal cord injury combined with promoting factor(GM-1) and treat the spinal cord injury rat model to explore the effective methods for treatment of spinal cord injury.Objective: To investigate the effect of combined treatment of fractionated irradiation and GM-1 injection on spinal cord injury in a rat model.Methods: 60 female Sprague-Dawley rats with spinal cord injury on the segment of T11-12 by Allen’s weight droppin were randomly divided into four groups: SCI group(n = 15), the SCI + fractionated irradiation group(n = 15), SCI+GM-1 injection group(15 rats) and the SCI + fractionated irradiation +GM-1 injection group(15 rats).GM-1 group and SCI + fractionated irradiation +GM-1 group were injected with GM-1 30 mg / kg after SCI for 7 days, SCI group and SCI + fractionated irradiation group were injected with saline for a week; irradiation groups were given a proper X ray irradiation on 2 weeks after SCI, the SCI group and SCI+GM-1 group be sham irradiated. Animals in each group were sacrificed at 6 weeks after SCI, and the BBB score, somatosensory evoked potential and histological examination were used to observe the spinal cord tissue structure and the recovery of neurological function in rats.Results: 4 rats were dead due to various reasons at the end of the experiment.The BBB score was increased from(1.3±0.4)to(3.0±0.5)in SCI group,increased from(1.4±0.5)to(7.1±0.3)in SCI+fractionated irradiation group,increased from(1.3±0.3)to(5.7±0.5)in SCI+GM-1 injection group,increased from(1.2±0.4)to(8.3±0.3)in SCI+fractionated irradiation+GM-1 injection group.The SEP results showed that the latency period of SCI group was longer than that SCI+irradiation groups(P<0.05);the count of NF was(21.2±3.7)in SCI group,was(65.3±6.5)in SCI+fractionated irradiation group,was( 37.8±6.2) in SCI+GM-1 injection group,was( 74.3±5.9) in SCI+fractionated irradiation+GM-1 injection group. The count of MBP was(278.2±10.3)in SCI group,was(196.4±12.7)in SCI+fractionated irradiation group,was(235.4±13.5)in SCI+GM-1 group,was(187.4±12.0)in SCI+fractionated irradiation+GM-1 group.(P<0.05).The count of GFAP in irradiation group was much less than control group and SCI+GM-1 group(P<0.05).The vimentin count in irradiation group was also less than control group and SCI+GM-1 group(P<0.05).Conclusion: The treatment of local X-ray fractionated irradiation combined with GM-1 injection on spinal cord injury in rats is more effective than a single treatment. The more reasonable combined treatments of spinal cord injury(SCI) need to be further studied.