大鼠复合型放射性下颌骨骨坏死动物模型建立及观察

Establishment and observation of a combined rat model of osteoradionecrosis

目的依据颌骨放射性骨坏死(ORNJ)新的临床诊断标准,探讨建立可模拟ORNJ不同临床分期的复合型动物模型的方法。方法健康SD雄性大鼠36只,随机分为6组:a1、b1、c1为实验组,a0、b0、c0组为对照组;根据生物学等效公式,实验组采用电子直线加速器对大鼠左侧下颌区进行照射,7Gy/次,1次/d,照射5 d;照射后6周,处死a1、a0组大鼠,并拔除b1、b0、c1、c0组大鼠左侧下颌磨牙;照射12、18周后,分别处死b1、b0组大鼠和c1、c0组大鼠并取下颌骨标本。对所有标本进行组织学观察和micro-CT扫描与骨组织形态学分析。使用SPSS 18.0软件包对数据进行统计学分析。结果实验组照射区可见a1组门齿生长障碍、b1组死骨暴露、c1组咬合错乱,化脓性感染与病理性骨折等症状;对照组无症状。组织学观察可见,实验组照射区骨髓腔与牙周膜内,炎性细胞浸润、纤维组织增生,b1、c1组还可见游离死骨;实验组门齿牙根与皮质骨渐进性破坏,c1组部分大鼠门齿牙根结构消失,周围皮质骨不连续;实验组空白骨陷窝增多,骨陷窝内骨细胞减少。micro-CT结果显示:相对骨体积(BV/TV):a1(0.401±0.053)、a0(0.615±0.037)、b1(0.309±0.041)、b0(0.717±0.040)、c1(0.200±0.026)、c0(0.724±0.041),实验组相对骨体积(BV/TV)均低于对照组;实验组间BV/TV值相比,a1>b1>c1,Pa1、b1=0.012、Pb1、c1=0.034、Pc1、a1=0.004,差异有统计学意义(P<0.05)。结论建立了一种能够模拟出轻度无症状(a1)、中度死骨暴露(b1)与重度联合症状(c1)三种不同ORNJ分型的复合型动物模型,为针对性研究ORNJ治疗方法提供了实验平台。

Objective To establish an osteoradionecrosis of jaws（ORNJ） rat model which could be used to simulate ORNJ at different clinical stages,according to the new clinical diagnostic standards.Methods Thirty six male SD rats were divided into 6 groups randomly.For group a1,b1 and c1,the left mandible of each rat weas irradiated at doses of 7.0 Gy for 5 fractions,which were equivalent to total doses of 70 Gy.Group a0,bo and co were sham irradiated,serving as control groups.Six weeks after irradiation,rats in group a0 and a1 were sacrificed,meanwhile,left mandibular molars of rats in group b1,bo,c1 and c0 were extracted.12 weeks and 18 weeks after irradiation,the rats in group bo,b1 and in group c0,c1 were sacrificed respectively.All the rats’ mandibles were taken.All samples were examined by clinical manifestation,micro-CT and histology methods.The data was analyzed with SPSS 18.0 software package.Results Alopecia and retardation of central incisor growth,at the irradiated site were seen in group a1.Exposed necrotic bone was found in all irradiated mandibles of group b1 and c1.Reduced condyle volume,dental sepsis and obviously loose,necrotic bone of the irradiated mandible were found in group c1.Fibrosis and inflammtions were found in medulla in all irradiated groups.In group b1,small pieces of sequestrum were seen around the tooth root.And large sequestrum,pathological fracture,overwhelming fibrosis and disrupted incisor root were seen in group c1.Significant increment of empty lacunae and decrement of osteocytes were observed in all irradiated groups,accompanying with the decreased BV/TV：a1（0.401 ±0.053）,a0（0.615±0.037）,b1（0.309±0.041）,b0（0.717 ± 0.040）,C1（0.200 ± 0.026）,co（0.724 ± 0.041）,Pa1、b1 = 0.012,Pb1、c1 = 0.034,Pc1、a1 = 0.004,a1〉b1〉c1,results were accepted as statistically significant at a value of P 〈 0.05.Conclusions A combined rat model that can stimulate three different stages of ORNJ was successfully established.This model could be served as a new platform for future studies on pathogenesis and treatment of ORNJ.