荷瘤小鼠肿瘤细胞凋亡显像的实验研究

Experimental study on tumor cell apoptosis imaging in vivo with ^(99)Tc^m-HYNIC-Annexin Ⅴ in mice tumor-bearing

目的研究细胞凋亡显像剂99Tcm-HYNIC-AnnexinⅤ的制备及其在荷瘤小鼠体内的生物分布特性和活体显像。方法采用双功能螯合剂HYNIC法锝[99Tcm]标记AnnexinⅤ,经高效液相色谱仪分离纯化并检测标记产物。建立荷肿瘤小鼠模型,在20~25 g昆明种小白鼠右前腋下皮下接种S-180肉瘤,生长1周。荷瘤小鼠在环磷酰胺腹腔内给药化疗72 h后,尾静脉注射99Tcm-HYNIC-AnnexinⅤ,分别于5 min3、0 min、1 h、3 h、6 h后进行SPECT显像和体内生物分布测定。实验结果应用SPSS 12.0统计学软件进行统计学分析。结果99Tcm-HYNIC-AnnexinⅤ的标记率达到95%,放射性化学纯度为99%。荷瘤小鼠在环磷酰胺腹腔内给药化疗后72 h显像可见:注射99Tcm-HYNIC-AnnexinⅤ后6 h肿瘤组织呈明显异常放射性浓聚灶。体内生物分布实验观察到,注射显像剂后6 h肿瘤组织的放射性摄取值(1.59±0.44)最高,与其他时相的肿瘤组织放射性摄取值比较P<0.05。99Tcm-HYNIC-AnnexinⅤ主要聚集在肾脏、肺脏和肝脏等,从肾脏排泄,其血流清除速度快,在注射后30 min,血液放射性摄取值(1.59±0.50)仅为5 min时(8.85±2.65)的20%(P<0.05)。注射显像剂后6 h,肿瘤/肌肉放射性摄取率比值(3.73±1.42)高于肿瘤/血液放射性摄取率比值(2.80±0.54)。结论99Tcm-HYNIC-Annexin V有望成为一种富有应用前景的活体细胞凋亡分子探针。

Objective To investigate in vivo the imaging and hoidistrihution characters of 99^Tc^m-HYNIC-Annexin V as tumor cell apoptosis imaging agent in tumor hearing mice. Methods Annexin V was laheled with technetium-99m using a hydrazino-nicotinamide （HYNIC） method, then isolated and identified with high performance liquid chromatography （HPLC）. One week after heing inoculated with S-180 sarcoma in the right upper limhs, the mice were randomized to receive a single dose of cyclophosphamide （150 mg/kg intraperitoneally）, and were injected through tail vein with 99 ^Tc^m HYNIC- Annexin V 72 hours later. The images and radioactivity in tissues were ohtained at 5 min, 30 min, 1 h, 3 h and 6 h postinjenction of imaging agent, respectively. The data of radioactivity in tissues were analyzed hy the statistic software of SPSS 12.0. Results The laheling efficiency and radiochemical purity of HYNIC-Annexin V laheled with technetium-99m reached 95% and 99%, respectively. Abnormal and marked uptake of radioactivity in tumor tissue in tumor-bearing mice received cyclophosphamide intraperitoneally was found to he at 6 h postinjection. Compared with that in tumor tissue at different time point of postinjection, the ratio （1.59 ± 0.44）% ID/g in tumor tissue at 6 h after injection of imaging agent showed the most important （P〈0.05）. The 99^Tc^m HYNIC Annexin V accumulated mainly in the kidney, lung and liver. It was cleared quickly through blood. In comparison with activity （[8.85±1. 65]%ID/g） at 5 min postinjection, 20 percents of initial activity remained in blood （[1.59±0.50]%ID/g） at 30 min. The ratio （[3.73±1.42]%ID/g） of tumor/muscle was higher than that of tumor/blood （[2.80±0. 54]%ID/g）. Conclusion 99^Tc^m- HYNIC Annexin V appears to be a potential and useful molecular probe of tumor cell apoptosis.