^(99m)Tc-HYNIC-Tat_(49-57)-DEVD的制备及其在健康BALB/c小鼠体内的生物学分布

Preparation of ^(99m)Tc-HYNIC-Tat_(49-57)-DEVD and Its Biodistribution in Normal Mice

目的:制备新型凋亡显像剂99mTc-HYNIC-Tat49-57-DEVD,研究其在健康小鼠体内的生物学分布,为其进一步应用于核素凋亡显像奠定实验基础。方法:设计合成Caspase-3特异性底物多肽,经化学修饰后与穿膜肽HIV Tat49-57连接,采用间接标记法,在螯合剂联肼尼克酰胺(HYNIC)和协同配体三羟甲基甘氨酸及乙二胺二乙酸的作用下,将连接有穿膜肽的Caspase-3底物Tat49-57-DEVD予Na99mTcO4标记,检测标记物的放化纯及稳定性,并研究其在健康BALB/c小鼠体内不同时间点(0.5,1,2和6h)的生物学分布。结果:合成的底物多肽经高效液相色谱及质谱分析鉴定为纯度≥99%的HYNIC-Tat49-57-DEVD干粉,标记产物99mTc-HYNIC-Tat49-57-DEVD的放化纯度为92.0%±1.6%,放置4h后其放化纯仍可达90.6%±1.4%。标记物在健康小鼠体内生物学分布实验显示其肾脏摄取值最高(0.5h其%ID/g值达5.93±0.08),肝脏次之,其余组织摄取较低。结论:显像剂99mTc-HYNICTat49-57-DEVD的制备方法可行,标记物稳定,在血液中的清除速度快,主要通过肝脏和肾脏排泄,为其进一步应用于体内凋亡显像奠定了基础。

Objective. To prepare a new imaging agent 99mTc-HYNIC-Tat49-57-DEVD, and to observe its distribution in normal mice, in order to provide a foundation of its imaging for apoptosis. Methods.Conjugating a substrate peptide of caspase-3 DEVD with a cell-penetrating peptide HIV Tat49-57 , chemically modified by HYNIC and labeled with 99mTc, a new imaging agent of apoptosis 99mTc-HYNIC-Tat49-57-DEVD was prepared. Its radiochemical purity and stability were measured, and then we observed its distribution in normal mice at different time point. Results： The new a- gent 99mTc-HYNIC-Tat49-57-DEVD was successfully prepared. Its radiochemical purity was （92± 1.6） %, and after 4 hours, the purity remained at （90.6±1.4）%. The distribution showed that the renal uptake was the highest （%ID/g=5.93±0.08 at 0.5 h）; the liver uptake was the sec- ond, while other organs showed low uptake. Conclusion：99mTc-HYNIC-Tat49-57-DEVD can be successfully prepared, its product was stable, and it excreted mostly through kidney and liver.