超顺磁性氧化铁标记脐带间充质干细胞后的活体MRI示踪

背景：核磁成像以其有效成像时间长，空间、时间分辨率高，对比度好的优点，在细胞活体示踪中显现出其独有的优势。 目的：观察超顺磁性氧化铁标记人脐带间充质干细胞的适宜浓度，及标记后干细胞移植入心肌梗死实验犬体内的MRI示踪成像。 方法：无菌条件下留取健康新生儿脐带，分离培养间充质干细胞并进行细胞表面标志检测。不同质量浓度的超顺磁性氧化铁标记第3代人脐带间充质干细胞，采用开胸冠状动脉结扎法建立犬心肌梗死模型并经心电图和病理对模型进行鉴定。56 mg/L超顺磁性氧化铁标记干细胞后移植实验组，相同质量浓度超顺磁性氧化铁注射对照组，分别于移植前、移植后第7，28天行核磁显像，第14，28天进行心肌病理检测。 结果与结论：分离得到的人脐带间充质干细胞表达间充质干细胞表面标记CD29，CD44及CD105均在90%以上，不表达造血细胞系的特征CD14，CD34与CD45。超顺磁性氧化铁质量浓度在14-84 mg/L时，对细胞增殖与活性无明显影响，标记率接近100%。心电图及组织病理检测均显示心肌梗死模型制作成功。56 mg/L的超顺磁性氧化铁标记细胞并移植后，核磁可对移植细胞清晰显像；病理检测可见普鲁士蓝染色阳性的细胞，生长方向同心肌细胞一致。提示14-84 mg/L范围的超顺磁性氧化铁可有效标记人脐带间充质干细胞，且核磁可以对超顺磁性氧化铁标记的人脐带间充质干细胞进行活体示踪。

Labeling human umbilical cord mesenchymal stem cells with superparamagnetic iron oxide and tracking in vivo with MRI after implantation

BACKGROUND:Nuclear magnetic resonance imaging shows unique advantage in cell tracking in vivo due to its long effective image displaying, high spatial and time resolution and good contrast. OBJECTIVE:To investigate an appropriate concentration of superparamagnetic iron oxide (SPIO) that can be used to label human umbilical cord mesenchymal stem cells, and to tract in vivo the labeled stem cells in canine with acute myocardial infarction by magnetic resonance imaging system. METHODS:Fresh human umbilical cords were obtained from full-term birth in sterile condition. Umbilical cord mesenchymal stem cells (UC-MSCs) from Wharton's Jelly were isolated and cultured. Passage 3 UC-MSCs were labeled with different concentrations of SPIO. Myocardial infarction was induced in an open chest canine model by artery occlusion and confirmed by electrocardiogram and histopathological findings. The UC-MSCs labeled or unlabeled with SPIO were transplanted into canines (experimental group, n=8; control group, n=4). Serial magnetic resonance imaging was performed before and 7, 28 days after transplantation. Histopathological observation was performed at 14 and 28 days. RESULTS AND CONCLUSION:Over 90% of isolated UC-MSCs expressed CD29, CD44, and CD105 but not the hematopoietic lineage markers (CD34, CD45). Nearly 100% of UC-MSCs could be effectively labeled by SPIO at a concentration of 14-84 mg/L without influences on cell proliferation and activity. Electrocardiogram and histopathological detection suggested that myocardial infarction was successfully induced. Remarkable low signal change was clearly observed in the transplanted location through magnetic resonance imaging and paralleled in the same direction with myocardial cells. Therefore, the UC-MSCs can be effectively labeled by SPIO at a concentration of 14-84 mg/L, and the labeled UC-MSCs can also be monitored in vivo by magnetic resonance imaging after transplantation.