磁共振成像及氧化铁粒子标记在干细胞治疗脑缺血大鼠中的应用

Application of MRI and iron oxide particle labeling in stem cell therapyof brain ischemic rats

目的探讨磁共振成像及氧化铁粒子标记在干细胞治疗脑卒中模型中的应用价值。方法线栓法建立9只大鼠大脑中动脉缺血模型,进行神经行为学评分、磁共振影像学和病理学评价,并对上述3项指标进行相关性分析。用超顺磁性氧化铁体外标记骨髓间充质干细胞,并另筛选18只脑缺血大鼠,分别接受缺血对侧皮层(n=6)、缺血同侧纹状体(n=6)的标记干细胞移植,并设对照组(n=6)。分别在脑缺血后1d、细胞移植后第1天、第7天及第14天进行磁共振扫描,观察各时间点的标记干细胞显示情况,并对各组之间梗死体积的变化进行统计学分析。结果神经行为学评分、磁共振影像学和病理学评价对大鼠脑缺血模型评价的相关性好。磁共振各序列均可显示局部移植的标记干细胞,梯度回波序列最敏感,T2像空间分辨力高。磁共振成像可显示局部移植标记干细胞随时间推移而产生的分布变化。干细胞治疗各组之间脑梗死体积变化无明显差异。结论磁共振成像是大鼠脑缺血模型评价的理想工具,配合氧化铁粒子标记干细胞可活体状态下了解干细胞移植后的分布变化。

Objective To explore the value of MRI and iron oxide particle labeling in stem cell therapy of stroke model. Methods Nine rats with middle cerebral artery occlusion were randomly selected and underwent Neurological Severity Scoring（ NSS）, MRI and pathological examination. The results of the 3 evaluation criteria were correlated. Bone marrow stromal cells were labeled with superparamagnetic iron oxide particles. Eighteen models were screened and divided into 3 groups based on different transplantation sites. MRI was performed at different time points. The MR appearance of labeled stem cell transplantation sites was observed. The relative infarct volume of the models in three groups were recorded and compared. Results Significant correlations among the NSS, MRI and pathological examination were found. Different MR sequences could depict local transplanted labeled stem cells and gradient echo sequence was the most sensitive method, while the T2WI showed its advantage of better temporal resolution. MR images showed the morphological changes of transplanted stem cells. The change of the relative infarct volume showed no significant differences among the three groups. Conclusion MRI is an ideal tool to evaluate the rat stroke model. MRI together with iron oxide particle labeling technique helps to in vivo track and monitor thetransplanted stem ceils.