磁标记大鼠肾脏骨髓间充质干细胞移植MR成像研究

MR imaging of implanted magnetically labeled rat bone marrow mesenchymal stem cells in normal kidney

目的对移植入大鼠正常肾脏的Fe2O3-PLL标记MSCs进行MR成像并探讨其成像技术。方法分离培养大鼠骨髓MSCs,Fe2O3-PLL标记细胞。将标记和未标记细胞经左肾动脉移植入大鼠肾脏,移植后即刻,第1、3、5、8天应用MRI对移植细胞进行活体示踪并与肾脏组织切片对照。结果MSCs的Fe2O3-PLL标记率近100%。标记细胞移植后T2WI肾脏皮质区信号强度明显下降,持续至移植后第8天。组织学分析见绝大多数标记细胞分布于肾小球内。结论1.5T磁共振仪可对移植入正常肾脏的Fe2O3-PLL标记细胞进行活体成像,T2WI信号变化最明显。

Objective To evaluate in vivo magnetic resonance （MR） imaging with a conventional 1.5 T system for depiction and tracking of intravascularly injected magnetically labeled bone marrow mesenchymal stem cells （MSCs） in rat normal kidney. Methods Rat bone marrow MSCs were isolated, purified, expanded and then incubated with home synthesized Fe2O3-PLL. Prussian blue stain was employed for identifying intracellular irons. MSCs were injected into renal arteries of 12 recipient rats （labeled cells in nine, unlabeled cells in three）. MR images of kidneys were obtained respectively before injection of MSCs, and immediately, 1, 3, 5, and 8 days after transplantation. MR imaging findings were analyzed, which were correlated with histological findings. Results Rat MSCs were successfully labeled, and labeling efficiency was almost 100%. Prussian blue staining of Fe2O3-PLL labeled cells revealed the presence of iron-containing vesicles or endosomes in the cytoplasm. In normal kidneys, the labeled MSCs were demonstrated as signal intensity loss in renal cortex on T2^＊- weighted MR images. The signal intensity decrease was visualized up to days 8 after transplantation. Histological analyses showed that most Prussian blue staining-positive cells were well correlated with the area where a signal intensity loss was observed in MRI. Conclusion 1, 5T MR imaging can monitor administered magnetically labeled MSCs in vivo in normal kidneys, especially on T2^＊ WI.