USPIO标记大鼠骨髓源性神经干细胞移植脑皮层影像及形态学初步研究

MRI and cell morphological study on rat bone marrow-derived neural stem cells labeled with USPIO after transplantation into cortex

目的将超小超顺磁性氧化铁（USPIO）Sinerem标记的大鼠骨髓源性神经干细胞移植鼠脑后，初步观察其在大脑中的活性、迁移和整合情况，确定MRI成像示踪Sinerem标记神经干细胞的可行性。方法分离SD大鼠骨髓基质细胞，体外培养诱导成骨髓源性神经干细胞。将Sinerem氧化铁和神经干细胞共孵育培养过夜。采用普鲁士蓝染色和透射电镜确定细胞内铁的摄取、定位情况。将标记细胞立体定向移植微注射到大鼠脑皮层。在不同时间点以SE序列T2WI行4．7T磁共振干细胞成像示踪，然后用组织学方法观察标记细胞在脑内的转归情况。结果Sinerem标记神经干细胞效率为98％～100％，普鲁士蓝染色显示铁颗粒存在胞质中，电镜显示铁颗粒集中于内涵体／溶酶体中；移植细胞体内的T2WI信号强度明显降低．可在4周时检测到细胞沿胼胝体迁移；组织学检测结果表明标记后的细胞可在脑内存活，并能沿神经纤维迁移。结论USPIO能有效地标记骨髓源性神经干细胞，利用磁共振成像可进行大脑中活体示踪监测。

Objective To observe the viability, migration and integration of bone marrow stromal cells-derived neural stem cells （BMSCs-D-NSCs） labeled with ultrasmall superparamagnetic iron oxide （USPIO） Sinerem and evaluate the availability of tracking them by MILl in brain after implantation. Methods Bone marrow stromal cells isolated from SD rats were cultured and induced into BMSCs-D-NSCs. These cells were co-incubated overnight with the Sinerem. Prussian blue staining and transmission electron microscopy were conducted for demonstrating intracytoplastic nanoparticles. Labeled cells were tracked with 4.7T MRI system in vivo with T2WI sequences at different time points after transplanted into brain cortex. And then these cells were observed and analyzed by histological methods. Results BMSCs-D-NSCs could be effectively labeled with Sinerem and the labeling efficiency was about 98%-100%. Prussian blue staining showed numerous blue-stained iron particles in the cytoplasm. Transmission electron microscope indicated that iron particles accumulated in endosomes/lysosomes. Remarkable lower signal density of labeled cells on T2WI was seen in vivo, and they had a slight migration along the corpus callosum since 4 weeks. Histology indicated that the labeled cells could remain alive in brain and move along nerve fiber. Conclusion BMSCs-D-NSCs could be labeled effectively with Sinerem, and MRI could be used to track these labeled cells in vivo.