^(131)I标记的抗甲状腺髓样癌人源单链抗体在荷瘤裸鼠的体内分布和放射免疫显像

Diodistribution and radioimmunoimaging of ^(131)I labeled scFv anti-medullary thyroid carcinoma in tumor bearing nude mice

目的测定^(131)I标记的抗甲状腺髓样癌(MTC)人源单链抗体(scFv)的放射化学纯度,并研究荷MTC细胞(TT cells)裸鼠^(131)I-scFv体内分布和体外放射免疫(RII)显像特点。方法氯胺T法对scFv进行^(131)I标记,Sephadex G200纯化标记抗体,三氯醋酸沉淀法测定标记率,纸层析法测定标记抗体在1、6、12、24h的放射化学纯度、室温稳定性和血清稳定性。构建荷TT细胞裸鼠模型,尾静脉注射^(131)I-scFv,分析^(131)I-scFv在裸鼠重要组织器官的分布情况,并于注射药物12、24、48、72h行SPECT正位静态显像,观察肿瘤内放射性浓集情况,肿瘤组织显像清晰时行SPECT/CT融合图像。结果标记抗体经纯化后,测得标记率为(78.60±0.08)%,放射化学纯度为(87.10±0.78)%,各个时间点的放射化学纯度均在90%以上。荷瘤裸鼠体内研究结果显示,^(131)I-scFv的放射性瘤/血、瘤/肌肉比值随时间的增长逐渐增高,48h达最高。RII显示,^(131)I-scFv可选择性聚集于肿瘤组织,48h时肿瘤显像与全身组织对比最清晰,此时融合图像可清晰显示肿瘤部位的放射性浓聚情况,体内分布和体外显像结果一致。结论成功标记了抗MTC人源scFv,生物活性较高,荷瘤裸鼠肿瘤的RII较好。

Objective To observe the radiochemical purity of ^131I-labeled human single-chain antibody（scFv）,and to analyze the distribution of ^131I-scFv in vitro and radioimmunoimaging（RII）in nude mice xenografted with medullary thyroid carcinoma（MTC）cells in vivo.Methods Specific anti-MTC^131I-scFv was labeled with chloramine T method,labeled scFv was puritied by Sephadex G200,labeling efficiency was measured with trichloroacetic acid precipitation method.Radiochemical purity,room temperature stability and serum stability of ^131I-scFv at 1h,6h,12 h,24hwas determined by paper chromatography.^131I-scFv was injected into the tail veins of nude mice xenografted with medullary thyroid carcinoma cells（TT cells）to analyze the distribution in various tissues and organs of mice.Anteroposterior static imaging was performed with SPECT at 12,24,48,72 hafter injection of ^131I-scFv to observe the radioactivity in tumor.Image fusion was performed with SPECT/CT when the tumor tissues was clearly visible.Results Labeling rate of purified ^131I-scFv was（78.60±0.08）%,radiochemical purity was（87.10±0.78）%,radiochemical purity at each time point were more than90%.Nude mice in vivo studies showed that with the increase of time,^131I-scFv radiological tumor/blood and tumor/muscle ratio increased after injection ^131I-scFv,which reached the highest at 48 h.The RII showed that the ^131I-scFv selectively accumulated in tumor tissue,and tumor imaging was most clear at 48 h.The image was well fused and the tumor was clearly seen at 48 hafter injection of ^131I-scFv.Conclusion Anti-MTC scFv can be successfully prepared and shows a high biological activity.Nude mice tumor RII shows a clear image.