国产125I巩膜敷贴器治疗兔眼脉络膜黑色素瘤的有效性及安全性研究

摘要

Background Choroidal melanoma (CM)is the most common primary intraocular tumor,and brachytherapy is one of the most common therapeutic modality in the treatment of the tumor.However,this irradiation approach has not been evaluated in China. Objective The present study was to analyze the effectiveness and safety of domestic 125I plaque irradiation in the treatment of CM. Methods Forty New Zealand albino rabbits were randomized into 5 groups with 8 rabbits 8 eyes (right eyes) in each group.CM models were established in 16 of 40 New Zealand albino rabbits by implanting the rat B16F10 melanoma cell fragments into the suprachoroidal space of right eyes.After 3 weeks,domestic 125I plaque was fixed at the location of CM in the irradiation group 1,and 8 rabbits with CM served as model control group.The clinical effectiveness of 125I plaque for CM was evaluated based on the fundus examination with indirect ophthalmoscopy,B scan ultrasonography,fundus photographs and color Dopplerimaging.Regarding the safety study,domestic 125I plaque was fixed on the normal right cycs of normal rabbits,while the plaques without 125I seeds were used as the sham group.No intervene was performed in the rabbits of blank group.The number of CD4+,CD8+ T cells in peripheral blood was detected by flow cytometry before plaques implanted and on 3,7,15 and 30 days after the plaque was removed.The animals were sacrificed and the eyes were obtained for histology examination.The use of the experimental animals complied with Statement of ARVO. Results After implantation of B16F10 melanoma cell fragments,CM grew steadily and rapidly with the similar size between irradiation group 1 and model control group ( P =0.550).One week after administration of the treatment,tumor size was(0.31±0.07 )cm in irradiation group 1 and (0.85±0.18 )em in the model control group,with the significant difference between them( P=0.001 ).Two week after application of 125I plaque,the size of tumor was smaller than that before irradiation (P=0.007 ).Histologically,the tumors were mostly limited beneath the pigment epithelial layer with less neovascularization,fibrosis in the tumor was found in some area in the irradiation group when compared with model control group.No significant differences were found in the proportions of CD4+,CD8+ T cells and CD4+/CD8+ at different time points in the irradiation groups of normal eyes and sham group (Fgroup =0.770,8.110,2.230; P=0.380,0.060,0.140; Ftime =0.770,3.220,4.230; P =0.550,0.170,0.004 ).Chronic inflammatory cells infiltration cornea,subconjunctival epithelial and selera surface,but sclera had no necrosis and organization.Conclusions These results suggest that domestic 125I plaque irradiation is effective for the treatment of CM,and has limited side effects on normal rabbits.%背景 脉络膜黑色素瘤(CM)是成人眼内常见的原发性恶性肿瘤,巩膜表面敷贴放射治疗(EPRT)是一种近距离放射疗法,是多年来治疗CM最常用的方法之一.但该治疗方法的研究与应用目前在国内报道较少,大多数的CM患者需行眼球摘除术. 目的 通过观察兔CM模型眼、正常兔眼经敷贴放射后的反应以及兔全身免疫状态,评价国产125I巩膜敷贴器的有效性及安全性.方法 新西兰大白兔40只,按随机数字表法分成5个组,每组8只兔8只眼(均取右眼).其中放射治疗组1及模型对照组用于评价国产125I巩膜敷贴器的有效性;放射治疗组2、伪放射对照组、正常对照组用于评价国产125I巩膜敷贴器的生物安全性.有效性研究:利用B16F10鼠皮肤黑色素瘤细胞株植入兔眼制作动物模型,造模3周后放射治疗组1模型兔眼放置国产125I巩膜敷贴器进行放射治疗,肿瘤局部照射总剂量为100 Gy,模型对照组不进行治疗.每日间接检眼镜检查,每周行眼底照相、B型超声、彩色超声多普勒检查.安全性研究:放射治疗组2正常兔眼放置巩膜敷贴器,伪放射对照组正常兔眼植入不带放射粒子的敷贴器外壳,正常对照组不作任何干预.放射治疗组2、伪放射对照组于放置敷贴器前及敷贴器取出后3、7、15、30 d抽取外周血,用流式细胞术检测外周血CD4+、CD8+T细胞数量.于放射治疗组1、模型对照组肿瘤种植后6周,放射治疗组2、伪放射对照组、正常对照组观察30 d后耳缘静脉空气栓塞法处死实验兔,对实验眼进行常规组织病理学检查. 结果 放射治疗组1、模型对照组间放置敷贴器前肿瘤的平均高度差异无统计学意义(P=0.550).放置敷贴器1周后,放射治疗组1肿瘤高度明显小于模型对照组,差异有统计学意义(P=0.001);放射治疗组1放置敷贴器2周后肿瘤高度较敷贴前明显缩小,差异有统计学意义(P=0.007).常规组织病理学检查发现,与模型对照组比较,放射治疗组1虽然仍有肿瘤细胞残存,但肿瘤内部血管明显减少且管径较细,肿瘤细胞排列紊乱,部分细胞空泡样变性,色素外露,大量纤维结缔组织增生.安全性研究中,放射治疗组2、伪放射对照组在各时间点CD4+、CD8+、CD4+/CD8+T细胞流式细胞术结果比较,差异均无统计学意义(F分组=0.770、8.110、2.230;P=0.380、0.060、0.140;F时间 =0.770、3.220、4.230;P=0.550、0.170、0.004).放射治疗组2、伪放射对照组表现为角膜、结膜上皮下、巩膜表面慢性炎性细胞浸润,未见巩膜坏死、机化等表现. 结论 国产125I巩膜敷贴器对兔眼CM的疗效确切,对眼部其他组织以及兔全身免疫状态的影响较小.