通用型脊髓打击器的研制与脊髓损伤动物模型的建立

Design of an universal spinal cord impact system and establishment of animal models of spinal cord contusion in rats and pigs

目的:研制一种通用型脊髓打击器,并评估其制作脊髓分级挫伤动物模型的稳定性。方法:依据重物坠落致伤原理,设计一种通用型脊髓打击器;将50只SD大鼠,分为3个实验组和1个对照组,实验组应用该打击器以质量为20g的打击棒在不同高度实施打击:12.5mm组(A组,n=12),25mm组(B组,n=12),50mm组(C组,n=14),对照组仅行椎板切除,不打击(n=12),分别于术前、术后第2天、1周至6周进行大鼠BBB运动评分,方差分析比较各组各时间点的BBB评分;术后1周和6周取材行组织学观察,用Photoshop CS软件直方图命令处理连续切片中最大受损面积的图像,计算大鼠脊髓最大受损面积比;对BBB评分与大鼠脊髓最大受损面积比进行相关分析。取4只国产家猪,应用该打击器以50g×150mm打击能量打击后制备胸髓半侧挫伤模型,于术前、术后第2天和第7天行改良Tarlov分级法评价猪后肢功能,并进行组织学观察。结果:通用型脊髓打击器能够准确定点、定高打击制作动物脊髓损伤模型。大鼠分级脊髓挫伤模型在各个时间点上BBB评分差异有统计学意义(P<0.05),A组和B组在术后1周后肢功能有不同程度恢复,而C组至术后6周均无明显恢复,对照组无功能障碍。大鼠和猪脊髓组织学表现均为以打击震中为中心的离心纵向损伤。大鼠脊髓最大受损面积比在各损伤组组内齐同、组间差异有统计学意义(P<0.05),脊髓最大受损面积比与BBB评分呈密切负相关关系(r=0.89807,P<0.001)。猪脊髓半侧挫伤后Tarlov分级法评价显示为中重度损伤。结论:研制的通用型脊髓打击器可成功建立不同损伤程度、稳定性高的大鼠急性脊髓挫伤模型,并可用于建立猪脊髓挫伤模型。

Objective：To develop a new universal impact device and evaluate its performance in producing animal models of spinal cord contusion in rats and pigs.Method：A new weight-drop device named SS-Ⅱ universal impact system （SS-Ⅱ impact system） was designed with the character of electromagnetic controlled impactor.50 Sprague-Dawley rats who underwent T10 laminectomy were randomly divided into 3 experimental groups according to impact height（impactor rod weighing 20 gram）：12.5mm（group A,n=12）,25mm（group B, n=12） and 50mm（group C,n=14） and 1 control group（n=12） without impacting.All rats were evaluated with the BBB locomotor rating scale prior to injury,and at 2d,1w,2w,3w,4w,5w,and 6w post-injury.The relative value of spinal cord maximum lesion area （RVSCMLA） in rats was measured by Photoshop CS software.The BBB scores and the RVSCMLA of rats were compared between groups at various time point with SAS 8.0 software.The relationship between the impact BBB scores and the RVSCMLA in rats was analyzed.4 domestic pigs who underwent total laminectomy of T8-T11 were impacted（50gxl50mm） by SS-Ⅱ impact system to establish the unilateral thoracic spinal cord contusive injury,and then were examined with modified Tarlov ranking method at pre-operation and 2 and 7 days of post-operation.Result：The SS-Ⅱ impact system could produce different levels of spinal cord injury in adult rat at specific height and dropping point.All the surviving rats with the impacted cord trauma presented definite functional deficits.Three experimental groups presented the deficits in BBB scales after injury with significant difference at various determined time points （P〈 0.05）.Both group A and group B showed some improvement after 1 week of injury.But the deficits of the group C did not show any improvement within 6 weeks of post-injury.Tbe control group had normal behaviour.The pigs presented behavioral deficits on both hind limbs with more severity in the traumatic side and the deficits belonged to the moderate to severe injury evaluated by Tarlov ranking method.Histological examination of the contused spinal cord in rats and pigs showed necrosis mainly involving the epicenter in the impact site.The RVSCMLA had the statistic difference between the groups at the same time point（P〈0.05） and was the same within the group.The RVSCMLA negatively correlated with the BBB score（r=0.89807.P〈0.001）. Conclusion：A new universal impact device has been successfully designed with high stability in producing reliable and controllable spinal cord injury models in rats and pigs.