体外磁共振成像对神经干细胞标记后弛豫活性的实验研究

Study on Relaxivity of Magnetically Labeled Neural Stem Cells with 4.7 Tesla MRI in Vitro

目的:研究超顺磁性氧化铁颗粒(SPIO)标记细胞后在细胞成像领域的应用价值。方法:SPIO与多聚赖氨酸(PLL)联合标记神经干细胞,使用4.7T磁共振对标记细胞进行T1WI、T2WI及T2*WI扫描,并测量标记细胞及未标记细胞的弛豫率R2和R2*。结果:①与未标记细胞相比,标记细胞于T1WI时信号强度平均上升24.06%,T2WI时信号强度平均下降50.66%,T2*WI时信号强度平均下降53.70%。②未标记细胞和标记细胞的T2分别为516 ms和77 ms,弛豫率R2分别为1.94/s及12.98/s;T2*分别为109 ms和22.9 ms,其弛豫率R2*分别为9.17/s及43.67/s。标记细胞的R2及R2*分别约增强了5倍及4倍。结论:SPIO能够有效的标记神经干细胞,明显提高标记细胞的R2及R2*,T2WI和T2*WI序列对显示标记细胞与未标记细胞间的信号差异较敏感。

Objective：To label neural stem cells with superparamagnetic iron oxide （SPIO） and study the relaxivity of labeled cells with 4.7 Tesla MRI in vitro. Methods：Rat neural stem cells were labeled with SPIO by the mean of receptormediated endocytosis. Prussian blue staining was conducted to identify the iron particles in these neural stem cells, and SPIO-labeled cells were examined with 4.7T MRI scanner in vitro. R2 and R2^＋ relaxation rates of labeled cells were calculated and compared with unlabeled cells. Results： ①4.7 Tesla MRI in vitro displayed that the signal intensity of labeled cells obviously decreased on T2WI and T2^＋WI,and slightly increased on T1 WI when compared with unlabeled cells. ②The R2 and R2^＋ relaxation rates of labeled cells in 4.7 Tesla MRI in vitro increased nearly 5-fold and 4 fold respectively when compared with unlabeled cells. Conclusion： SPIO can be used to label neural stem cells effectively and can increase the relax ation rate of labeled cells obviously in vitro.