^(99)Tc^m-Annexin V衍生物的制备及其生物分布和凋亡显像

Preparation and biodistribution of ^(99)Tc^m-Annexin V derivate and a primary animal study

目的探讨^(99)Tc^m 直接标记带有10个连续组氨酸的膜联蛋白 V(Annexin V)衍生物的可行性,研究其在健康小鼠体内的分布和肺癌裸鼠模型凋亡显像。方法直接标记法制备^(99)Tc^m-Annexin V 衍生物,并测产物放化纯、胶体含量及健康小鼠体内不同时间点(5,30 min 和1,2,4,6,12,24 h)的生物分布,DAS 2.0软件拟合计算药代动力学参数。建立荷 H460非小细胞肺癌裸鼠模型,分为紫杉醇诱导化疗组(5只)和未治疗对照组(5只)。紫杉醇诱导化疗后48 h,于裸鼠尾静脉注射^(99)Tc^m-Annexin V 衍生物18.5 MBq,2和4 h 时进行凋亡显像,勾画 ROI 并计算肿瘤与对侧正常组织(T/NT)放射性比值。结果放化纯达(98.01±1.67)%,3 h 后放化纯仍可达(95.45±1.34)%,胶体含量为(3.31±1.37)%。健康小鼠体内分布实验表明肾脏对该示踪剂摄取最高,肝、脾摄取较少。DAS 2.0软件拟合得到时间-放射性曲线符合二室模型特征,分布相半衰期(T_(1/2α))为(21.18±5.95)min,清除相半衰期(T_(1/2β))为(69.32±0.10)min。荷瘤鼠显像示,给药后2 h 即可获得清晰的图像,紫杉醇诱导化疗组2和4 h 的 T/NT 比值为3.85±1.10和4.63±0.97,明显高于对照组(1.60±0.29和1.71±0.43,P<0.01)。结论该Annexin V 衍生物易于^(99)Tc^m直接标记,方法简便,标记物在血液中清除迅速,肝、脾摄取少,易得到高清晰图像。

Objective Imaging cell apoptosis with radionuclide tracer was reported in monitoring the therapy effect, evaluating the patients＇ prognosis and recommending the tumor treatment as well as research and development of new anti-tumor drugs. This paper was to evaluate the feasibility of direct labeling of Annexin V derivate with ten consecutive histidines and observe its biodistribution in normal mice. Methods ^99Tc^m-Annexin V derivate was prepared by direct-labeling method, and the radiochemical purity was measured. The biodistribution was studied and the pharmacokinetic parameters were determined by DAS 2.0 software. Nude mice bearing H460 tumor were divided into two groups, one group was treated with paclitaxel for 48 h, and the other untreated as control. Eighteen point five MBq of ^99Tc^m-Annexin V derivate was injected via tail vein and images were acquired at 2 and 4 h after injection. The radioactivity ratio of tumor/contralateral tissue （T/NT） was calculated over ROI. Results The radiochemical purity was （98.01 ± 1.67）%, and maintained after 3 h. The biodistribution showed high uptake of the tracer in kidney and low uptake in liver and spleen. The pharmacokinetics indicated two-component model with the distribution phase half-life （T1/2α ） of （21.18 ± 5.95 ） min and the elimination phase half-life （T1/2β） of （69.32 ± 0.10） min. Focal uptake of ^99Tc^m-Annexin V derivate was visualized in tumor at 2 h after injection. The T/NT in chemotherapy group at 2 and 4 h were 3.85 ± 1.10 and 4.63 ± 0.97, respectively, which were much higher than that of control group （1.60±0.29 and 1.71 ±0.43, P〈0.01）. Conclusions The Annexin V derivate was directly labeled with ^99Tc^m and quickly cleared from blood. High quality image could be acquired because of low radioactivity accumulated in liver and spleen.