中文摘要：

目的：鉴定CD133^＋-HepG2肝癌细胞的干细胞特性，然后通过^131I标记CD133单克隆抗体（^131I-CD133抗体），研究其在人肝癌HepG2细胞裸鼠模型体内的生物学分布及对移植肿瘤的放射免疫靶向性。方法：采用免疫磁珠法分选出人肝癌CD133^＋-HepG2细胞，应用FCM法检测其CD133表达率，然后应用体外成球、克隆形成及体内成瘤实验鉴定其干细胞特性；采用氯胺T法制备^131I—CD133抗体，并鉴定其标记率、放化纯度、稳定性及细胞结合活性；建立HepG2肝癌裸鼠模型，向模型鼠尾静脉注射^131I—CD133抗体，2、12、24和48h时测量并计算模型鼠体内各组织器官的每克组织百分注射剂量率；同时采用同型^131I—IgG作为对照，比较24h时2种标记物在HepG2肝癌裸鼠模型体内的各组织生物分布及肿瘤／非肿瘤组织比值。结果：成功分选出人肝癌CD133^＋-HepG2细胞，其CD133表达率为（93．58±3．74）％，并具有很强的体外成球、克隆形成及体内成瘤能力。^131I—CD133抗体的标记率为（86．95±1．16）％，放化纯度为98．07％；与血清孵育48h后，^131I—CD133抗体的放化纯度仍为（89．63±0．64）％；^131I—CD133抗体与CD133^＋-HepG2细胞的结合率最高可达（69．30±0．69）％。^131I—CD133抗体注入HepG2肝癌裸鼠模型后，随着时间延长，包括肿瘤在内各组织器官的每克组织百分注射剂量率均降低；与^131I—IgG对照组相比，^131I—CD133抗体组在24h时的肿瘤放射性摄取量以及肿瘤／非肿瘤组织（除血液和胃）比值明显增加（P〈0．05）。结论：^131I—CD133抗体在裸鼠体内能有效结合CD133^＋肝癌细胞，从而聚集在肿瘤组织中。推测CD133有可能成为肝癌治疗的新靶点。

英文摘要：

Objective： To identify the stem cell characteristics of human hepatocellular carcinoma CD133-positive （CD133^＋）-HepG2 cells, and to investigate the systemic distribution of ^131I-labeled anti- CD133 （^131I-CD1 33） antibody and their radio-immunotargeting in transplanted tumors of HepG2 cells in nude mice. Methods： Magnetic activated cell sorting （MACS） method was used to sort CD133^＋ cells from HepG2 cells. Flow cytometry was used to detect the expression of CD133 of the sorted cells. The stem cell properties of the sorted CD133^＋-HepG2 cells were validated by in vitro sphere-forming assay and colony-formation assay and in vivo tumor formation experiment. ^131I-CD133 antibody was prepared using chloramine T method, and its labeling efficiency, radiochemical purity, stability and cell-binding property were measured. The HepG2 tumor-bearing nude mouse model was established and injected with ^131I-CD133 antibody via tail vein. The percentage of inJected dose per gram of tissue （%ID/g） in major organs was calculated at 2, 12, 24, and 48 h after injection. Using isotype ^131I-IgG as a control, the biodistributions of these two labels in different organs/tissues and the tumor were compared, and a tumor/non-tumor （T/NT） ratio was calculated at 24 h after injection. Results： The CD133^＋-HepG2 cells were successfully sorted with a CD133 expression rate of （93.58±3.74）% and had strong abilities of sphere-, colony- and tumor-formation in vivo. The labeling efficiency and the radiochemical purity of ^131I-CD133 antibody were （86.95±1.16）% and 98.07%, respectively. After incubation with serum for 48 h, the radiochemical purity of ^131I-CD133 antibody was similar [（89.63± 0.64）%] to the value before incubation. The binding rate of ^131I-CD133 antibody to CD133^＋-HepG2 cells was up to （69.30±0.69）%. After intravenous injection of ^131I-CD133 antibody into HepG2 tumor-bearing mice, the %ID/g values of ^131I-CD133 antibody were reduced over time in different organs and tissu