SPIO标记BMSCs移植治疗局灶性脑梗死的MRI示踪研究

摘要

目的：通过采用磁共振技术示踪在体超顺磁性氧化铁(super paramagnetic iron oxide, SPIO)标记骨髓间充质干细胞(bone marrow mesenchymal stem cells, BMSCs)，观察SPIO标记的BMSCs在局灶性脑梗死模型中的迁移及治疗情况。材料与方法28只雄性SD大鼠随机分为正常对照组(CON, n=4)、假手术组(SHAM, n=4)、局灶性脑梗死对照组(MCAO+SPIO，n=10)和SPIO标记BMSCs治疗组(MCAO+SPIO-BMSC, n=10)。通过普鲁士蓝染色法及CCK8法选取SPIO标记BMSCs的最佳浓度，并使用立体定向注射方法进行最佳浓度SPIO及SPIO-BMSC的移植，术后第1、9、20、30、43天行1.5 T MRI扫描，检测两者在局灶性脑梗死中的生物学行为，普鲁士蓝染色观察细胞迁移分布情况。结果当SPIO标记浓度为50μg/ml时，BMSCs普鲁士蓝染色效率为100%，CCK8检测增殖活性较对照组及75μg/ml组均有明显差异(P＜0.05)。使用T2WI和SWI序列均能明确检测到MCAO+SPIO组和MCAO+SPIO-BMSC 组中移植区域信号减低。与T2WI序列相比，SWI序列显示低信号范围更广，示踪时间更长。与MCAO+SPIO组比较，MCAO+SPIO-BMSC组可见SPIO标记的BMSCs向缺血梗死区迁移。普鲁士蓝染色检查发现：普鲁士蓝染色阳性的细胞聚集在梗死区域周围。结论MRI技术能够有效示踪50μg/ml SPIO标记的BMSCs，显示BMSCs在局灶性脑梗死模型中随时间变化发生的生物学行为，并对BMSCs在局灶性脑梗死中的迁移治疗情况进行动态观测。%Objective:To explore the feasibility of MRI technology in tracing bone marrow mesenchymal stem cells labeled with SPIO, and observe migration and therapeutic condition of BMSCs in focal cerebral infarction model. Materials and Methods: Investigate label efficiency and proliferation activity of three different concentrations of SPIO (25μg/ml, 50μg/ml, 75μg/ml ) by Prussian blue staining and CCK8 method. A total of 28 male SD rats were randomly divided into normal control group (CON, n=4), sham operation group(SHAM, n=4), focal cerebral infarction group treated with SPIO only (MCAO+SPIO, n=10), and focal cerebral infarction treated with optmal SPIO-BMSCs (MCAO+SPIO-BMSC, n=10), MRI scan was underwent on 1 day, 9 days, 20 days, 30 days, 43 days after cell transplantation. Distribution of cell migration were observed by Prussian blue staining. Results:When label concentration was 50μg/ml, Prussian blue staining efficiency was 100%. Compared with control group and 75μg/ml group, 50μg/ml group was significantly different (P<0.05). In MCAO+SPIO and MCAO+SPIO-BMSC groups, transplanted cells on T2WI and SWI sequences obviously show signal reducing area. Compared with T2WI sequences, SWI sequences show a longer, wider range of low signal. Compared with MCAO+SPIO group, MCAO+SPIO-BMSC group can observe that bone marrow mesenchymal stem cells migrate into infarction areas. Prussian blue staining showed that positive cells gathered around the infarction area. Conclusion:MRI techniques can effectively trace mesenchymal stem cells labeled with 50μg/ml SPIO, monitor migration and therapeutic condition of BMSCs in focal cerebral infarction model, and evaluate the imaging improvement of focal cerebral infarction.