超顺磁性氧化铁标记大鼠骨髓间充质干细胞的磁共振成像研究

In vitro MR imaging of superparamagnetic iron oxide labeled bone marrow mesenchymal stem cells from SD rat

目的：探讨超顺磁性氧化铁纳米粒子（Superparamagnetic iron oxide，SPIO）体外标记大鼠骨髓间充质干细胞（Bone marrow mesenchymal stem cells，BMSCs）的适当浓度和不同标记浓度对细胞的生物学活性影响，以及经MR成像的特征等。方法：选取第5代细胞进行不同浓度SPIO标记，运用光学昆微镜观察铁颗粒在细胞内的位置、分布及标记率；选取适当浓度标记量，使用1．5T磁共振进行T1WI、T2WI、T2＊WI扫描，测量不同扫描序列标记细胞管的信号强度改变，并进行统计学分析。结果：标记后的铁颗粒均位于细胞质内；含量在25～50μg Fe／ml的培养液是SPIO标记干细胞的安全浓度，在此浓度阈值标记后孵育24h即可有效标记细胞97％～100％；SPIO标记的MSCs在T1WI，T2WI及T2＊WI序列信号均降低。结论：SPIO可以简便标记MSCs。并且在适当浓度下对MSCs的生物学活性没有影响，MR T2WI和T2＊WI序列可有效显像磁性标记的干细胞，为下一步活体试验奠定基础。

Objective ：To explore the proper concentration of superparamagnetic iron oxide （SPIO） labeling bone marrow meseehymal stem cells and the biological influence of different labeling concentrations,and to evaluate the characteristics of magnetic resonance imaging by a 1.5 T MR scanner. Methods： BMSCs （5^th） were incubated with different concentrations of SPIO particles. The location, distribution and the labeling ratio of SPIO particles in cells were observed. At an optimal concentration, samples of SPIO-labeled and unlabeled MSCs suspension in agar were imaged by MRI with T1WI,T2WI and T2＊WI. and the signal intensity were measured and statistically analyzed. Results： Labeled SPIO particles were stained in cytoplasm. BMSCs were efficiently labeled （97% to 100% ） in culture at 24 hours and particle concentrations（25 to 50 μg Fe/ml medium ）. Compared with unlabeled cells, BMSCs loaded with SPIO had similar viability and proliferation profiles at this proper range of labeling concentration. SPIO labeling caused a stronger low signal attenuation effect in T1WI ,T2WI and T2＊WI. Conclusion：BMSCs can be easily and efficiently labeled by SPIO without interference on the cell viability and proliferation, MRI visualization of SPIO-labeled MSCs is feasible, which provrdes basis for future in vivo studies.