改良激素性股骨头坏死动物模型的建立与评价

背景：在股骨头坏死发病机制的研究中，目前仍缺乏有效的动物模型，各种股骨头坏死治疗新方法的发展需要能够模拟人股骨头坏死自然病程动物模型的基础实验。 目的：通过联合应用马血清和低剂量甲基强的松龙建立激素性兔股骨头缺血性坏死动物模型。 方法：20只健康日本大耳白兔随机分成2组。实验组动物注入马血清，间隔2周后，再次注入马血清，第1次注射马血清后24 h肌肉注射甲基强的松龙，每隔1周注射1次，共8周。对照组动物单纯注射同等量的生理盐水。于第1次注射马血清前、注射甲基强的松龙后2，4，8周行血液学检查。并分别于注射甲基强的松龙后4，8周行MRI检查、苏木精-伊红染色和电镜观察股骨头缺血坏死情况。 结果与结论：与对照组比较，2，4，8周实验组三酰甘油、胆固醇均明显上升(P < 0.05)；激活部分凝血活酶时间则明显下降(P < 0.05)。4周实验组MRI显示部分动物可见局部信号改变，8周时可见皮质下出血；对照组比较，4，8周实验组骨髓周围有坏死的骨髓细胞碎片存在，空骨陷窝率逐渐增加(P < 0.01)；4周时实验组个别骨细胞结构模糊不清，或有大空泡；8周时部分骨细胞核破裂、核溶解，凋亡细胞大量出现，骨胶原结构排列紊乱。结果证实联合运用激素和马血清明显提高股骨头缺血性坏死的发生率，能够较好地建立激素性兔股骨头缺血性坏死动物模型。

Establishment and evaluation of a modified animal model of steroid-induced avascular necrosis of femoral head

BACKGROUND: So far, the pathogenesis of steroid-induced avascular necrosis of femoral head was still unclear; furthermore, the valid animal model was lack, and the developments of different treatments were based on the animal models, which could simulate the natural pathogenesis course. OBJECTIVE: To explore the feasibility of setting up animal models of steroid-induced avascular necrosis of femoral head by combining low-dosage methylprednisolone (MPS) with equine serum (ES). METHODS: Twenty healthy Japanese white rabbits were randomly divided into experimental group and control group. Experimental group was intravenously injected with ES, and another injection of ES was performed two weeks later. MPS was intramuscularly injected at 24 hours after the first ES injection, once a week for 8 weeks in total. Control group was injected with the same dose of saline. Hematologic studies were performed before the first ES injection, 2, 4, and 8 weeks after MPS injection. Meanwhile, other examinations were carried out including magnetic resonance imaging (MRI), hematoxylin-eosin staining, and transmission electron microscope at 4 and 8 weeks after MPS injection, respectively. RESULTS AND CONCLUSION: Compared with control group, triacylglycerol and cholesterol levels were significantly increased in the experimental group after 2, 4, and 8 weeks (P < 0.05), but partial thromboplastin time was significantly decreased (P < 0.05). MRI in the experimental group after 4 weeks demonstrated that local signals were changed in some animals and subcortical hemorrhage was observed after 8 weeks. Compared with control group, necrotic bone marrow cell debris was located surrounding bone marrow in the experimental group after 4 and 8 weeks, and blank bone lacuna rate was gradually increased (P < 0.01). Structure of some osteocyte was unclear in the experimental group after 4 weeks, and large vacuoles were observed. After 8 weeks, part of osteocyte had caryorrhexis and caryolysis, apoptotic cells appeared abundantly, and the structure of bone collagen was confused. Combination of ES and steroid significantly increased incidence of osteonecrosis in rabbits and contributed to set up animal models of steroid-induced avascular necrosis of femoral head.