SPIO-shRNA双功能分子探针药动学及活体MR成像研究

Pharmacokinetics and MR imaging of SPIO-shRNA dual functional molecular probe in vivo

本研究探讨SPIO-sh RNA双功能分子探针在活体内的药代动力学特征及磁共振(magnetic resonance,MR)成像无创评估其主要脏器分布。将18只新西兰大白兔随机分为3组,分别注射不同剂量的分子探针,于注射前30 min及注射后不同时间点采血,测量铁含量以分析探针药代动力学。24只昆明(KM)小鼠随机分为4组,以每只小鼠尾静脉注射200μL生理盐水为对照组,另3组分别注射不同剂量的分子探针,于注射后24 h行MRI扫描,扫描结束后立即取肝、脾、肾、脑及肌肉,制作切片行普鲁士蓝染色,观察探针在体内主要脏器组织的分布情况。结果显示,本探针的药代动力学符合二室模型,半衰期超过3 h;MRI显示探针在正常小鼠体内主要分布于肝脏与脾脏,肝脾MRI信号随着探针剂量的增加而降低(均P<0.05),组织切片普鲁士蓝染色证实了MRI检查结果,同时显示探针绝大部分能够逃避单核吞噬细胞系统的吞噬。本研究明确了SPIO-sh RNA分子探针在动物体内的药代动力学及主要脏器分布,为进一步的肿瘤活体成像时间及剂量的选择提供了重要参考价值。

In this study, we investigated the pharmacokineties parameters of SPIO-shRNA dual functional molecular probe and observed the main organ distribution by MRI in vivo. Eighteen New Zealand white rabbits were randomly divided into three groups and injected intravenously with different doses of SPIO-shRNA molecular probe, respectively. The blood samples were collected to analyze the pharmacokinetie parameters by measuring the iron content at 30 minutes before and after the injection. Twenty-four Kun Ming （KM） mice were randomly divided into 4 groups： the control group was injected intravenously with physiological saline 200 ~tL per mouse via the tail vein, the other 3 groups were injected intravenously with different doses of SPIO-shRNA molecular probe. MRI observation was performed in 24 hours, and the liver, spleen, kidney, brain and muscle were collected for iron quantification with Prussian blue staining to determine distribution of the SPIO-shRNA molecular probe in the main organ in vivo. Our results suggest that the molecular probe blood half-life is more than 3 hours. The data of MRI suggest the probe was distributed in liver and spleen, and the MRI signal was reduced with the increase in probe＇s doses （P〈0.05）. The results of Prussian blue staining confirmed the results of MRI. Most of the probe could escape the phagocytosis of mononuclear phagocyte system. Our data provide the pharmacokinetic and distribution of SPIO-shRNA molecular probe in organs. Meanwhile, it suggests the choice of the time and dose of probe for MR imaging of tumor in vivo.