摘要
目的制备细胞凋亡显像剂99mTc-annexinⅤ,并在荷肉瘤小鼠体内对凋亡肿瘤组织进行活体显像。方法利用硫酸铵沉淀和Octyl-Sepharose疏水层析纯化来源于毕赤酵母重组表达、带有内在螯合位点的annexinⅤ。通过葡庚糖酸盐配体在annexinⅤ上直接标记放射性核素99mTc,SephadexG-25脱盐处理制备99mTc-annexinⅤ。在Balb/C小鼠右侧腋下接种肉瘤株S-180,1周后荷肉瘤小鼠经腹腔注射化疗药物环磷酰胺诱导肉瘤细胞凋亡。化疗18h后经小鼠尾静脉注射99mTc-annexinⅤ,扫描6h后肿瘤组织的SPECT图像。分别于放射性药物注射后0.5、1、3、6h处死动物,测定各脏器、组织的放射性计数,分析99mTc-annexinⅤ在荷肉瘤小鼠体内的生物分布。结果经过硫酸铵沉淀和Octyl-Sepharose疏水层析纯化,annexinⅤ纯度达到95%。直接标记和脱盐处理制备出的99mTc-annexinⅤ放射性化学纯度为90%。将99mTc-annexinⅤ注射到环磷酰胺处理的荷肉瘤小鼠体内,肿瘤组织能够显像。结论我们标记合成了99mTc-annexinⅤ,该探针可以活体显示肿瘤组织的凋亡情况,可能为临床应用和药物开发提供了一种手段。
Objective To prepare apoptosis imaging agent ^99mTc - annexin Ⅴ and perform to imaging of apoptotic tumor tissue in vivo in sarcoma - grafted mice. Methods Annexin Ⅴ with endogenous chelating sites were expressed in pichia pastoris and purified from cultures medium by ammonium sulfate precipitation and octyl - sepharose chromatography. The purified protein was directly labeled with radioactive isotope ^99mTc in glucoheptonate solution and ^99mTc -annexinⅤ was separated from the reaction mixture by Sephadex G -25 desalring. Sarcoma strain S - 180 was injected to the right flank of Balb/C mice and one week later, chemotherapeutic drug cyclophosphamide was injected intraperitoneally to induce tumor apoptosis for 18 h. ^99mTc -annexinⅤ was injected to cyclophosphamide -treated mice via tail vein and the mice were scanned by SPECT 6h after radioactive probe administration. Bio - distribution analysis was carried out at 0.5, 1,3,6 h after ^99mTc - annexin Ⅴ injection by dissecting animal organs and counting their radioactivity. Results The purity of annexin Ⅴ reached up to 95% after ammonium sulfate precipitation and octyl -sepharose hydrophobic interaction chromatography. The radiochemical purity of ^99mTc - annexin Ⅴ was 90% after direct labeling and desalting. Cyclophosphamide - treated tumor can be imaged by ^99mTc - annexinⅤ in sarcoma - grafted mice. Conclusions We labeled and synthesized ^99mTc - annexinⅤ ,which can be used to visualize apoptotic tumor in vivo. ^99mTc -annexinⅤ may act as an important tool in clinical application and drug development.
出处
《医学研究杂志》
2007年第2期30-33,共4页
Journal of Medical Research
基金
霍英东肺癌专项基金资助
