磁性／荧光量子点双功能纳米粒子标记大鼠骨髓间充质干细胞

Magnetic/luminescent quantum dots bifunctional nanopartides labeling of rat bone mesenehymal stem cells

目的利用磁性／荧光量子点双功能纳米粒子双标记大鼠骨髓间充质干细胞（BMSC），探讨标记效率和可行性。方法分离、纯化及培养大鼠BMSC。制备二氧化硅（SiO2）同时包裹四氧化三铁（Fe3O4）和碲化镉（CdTe）荧光量子点的磁性／荧光双功能纳米粒子Fe3O4@CdTe@SiO2，利用铁浓度为25μg／ml的Fe3O4@CdTe@SiO2标记BMSC，未标记的BMSC作为对照组。通过荧光显微镜观察细胞内纳米粒子的荧光表达情况。双标记后的BMSC分成8个不同数量级（3×10^6～1×10^3个），应用1．5T磁共振扫描仪进行T1WI、T2WI和T2^＊WI3个序列成像。分光光度计测量细胞铁含量，普鲁士蓝染色显示细胞内铁。结果荧光显微镜下可见双标记组细胞内Fe3O4@CdTe@SiO2纳米粒子显示为红色荧光，细胞标记率达到90％以上。磁共振成像可见3×10^6～5×10^4双标记组细胞较对照组T2WI、T2^WI信号减低，两组之间的信号差异随数量级减小而相应减小，T2^＊WI信号变化最明显，T2WI次之。细胞铁含量为（14．05±4．15）pg／细胞，普鲁士蓝染色可见双标记细胞胞质内蓝染的含铁颗粒。结论Fe3O4@CdTe@SiO2纳米粒子可同时对大鼠BMSC进行磁性和荧光双标记，有望成为磁共振和光学成像活体示踪移植后BMSC的有效手段。

Objective To evaluate the dual-labeling efficiency of magnetic and luminescent quantum dots bifunctional nanoparticles to rat bone mesenchymal stem cells （BMSC）. Methods Rat BMSC were isolated, purified, and expanded. Magnetic/luminescent bifunctional nanoparticles （ Fe3O4 @ CdTe@ SiO2 ）, were prepared by using silicon dioxide（ SiO2 ） to encapsulate simultaneously Fe3 04 and CdTe quantum dots. BMSC were incubated with the Fe3O4 @ CdTe@ SiO2 nanopartieles which iron concentration was 25 μg/ml. Fluorescence microscope was used to detect the fluorescence of the intracellular nanoparticles. The dual-labeled BMSC with various concentration underwent ex vivo MR imaging with T1WI, T2WI and T2 WI sequences. To show the intraeellular iron of labeled cells, prussian blue stain was performed. Speetrophotometer was used to detect the iron concentration in the cells. Results Intracellular red fluorescence of F3O4@ CdTe@ SiO2 can be observed via fluorescent microscopy. Rat BMSC could be effectively dual-labeled with approximately 90% efficiency. The MR images with T2WI and T2 WI sequences, especially with T2 WI sequence, showed that the signals of the dual-labeled BMSC were lower than those of the unlabeled cells. Cellular total iron is 14. 05 ± 4. 15 pg per cell. Iron containing intracytoplasmic vesicles could be observed with Prussian blue staining. Conclusion Rat BMSC can be dual-labeled successfully with F3O4 @ CdTe @ SiO2 magnetic/luminescent bifunctional nanoparticles successfully, and might serve as a tool for magnetic resonance imaging and in vivo optical imaging.