超顺磁性氧化铁纳米粒子标记心脏内骨髓间充质干细胞及活体磁共振示踪的实验研究

Labeling mesenchymal stem cells in the heart with superparamagnetic iron oxide nanoparticles in vitro and tracking after implantation with MRI in vivo

目的:探讨超顺磁性氧化铁纳米粒子(superparamaganetic iron oxide nanoparticles,SPIO)能否作为示踪剂在磁共振下对移植入梗死边缘区的骨髓间充质干细胞(mesenchymal stem cells,MSCs)进行体内追踪。方法:体外培养MSCs用SPIO标记后普鲁士蓝染色观察标记率及MTT法观察其对MSCs活性的影响。建立大鼠急性心肌梗死模型,分磁性细胞移植组、非磁性细胞移植组、纳米粒子移植组,分别于梗死心肌边缘区多点注射SPIO标记MSCs、未标记MSCs、SPIO。术后3、7、14、21d行MRI检查后处死大鼠,进行组织学检查。结果:SPIO标记MSCs阳性率达95%,对MSCs的活性和分化无明显影响。磁性细胞移植组术后3、7、14d在MRT2像显示的低信号注射点为65.6%、56.3%、18.8%,术后21d不能显示注射点。随时间的延长,低信号区域边界模糊,范围扩大,信号对比度降低。结论:SPIO可以作为示踪剂在磁共振下对移植入大鼠梗死边缘区的MSCs进行体内追踪,该方法能够作为一种无创的手段来示踪体内干细胞的迁移及转归。

Objective To explore whether superparamaganetic iron oxide nanoparticles （SPIO） can be used as a tracer for tracking the implanted mesenchymal stem cells（MSCs） in the infarct border zone under MRI scanning. Methods MSCs were cultured in vitro, labeled with SPIO, and then stained with Prussian blue to assess the rate of the labeling cells. MTF assay was used to investigate the effect of SPIO on the viability of MSCs. The rat model of acute myocardial infarction was established and then the rats were assigned to receive injections of MSCs with or without SPIO labeling （magnetic cell group and non-magnetic cell group）, or injections of SPIO （SPIO group） to the infarct border zone at different points. MRI scanning was performed at days 3, 7, 14, and 21 after injection, the cardiac tissues were then histologically examined. Results 95% of the MSCs were successfully labeled with SPIO. No adverse effect of SPIO on the viability and differentiation of MSCs was found. T2 hypointense signal was detectable in 65.6% of injection points at day 3, 56.3% at day 7, and 18.8% at day 14, and became undetectable at day 21. The hypointense zones were enlarged with poorly defined borders and the signal contrast was decreased in a time-dependent manner. Conclusion SPIO can be used as a tracer for tracking the implanted MSCs in the infarct border zone under MRI scanning.