胎鼠神经干细胞超顺磁性氧化铁颗粒标记移植后MRI研究

目的:探讨超顺磁性氧化铁颗粒(SPIO)标记神经干细胞的方法,以及标记细胞正常大鼠脑内移植后MR成像的方法学研究。方法:多聚左旋赖氨酸介导的SPIO标记胎鼠神经干细胞,进行台盼兰染色和普鲁士兰染色分别检测标记细胞的存活率和标记率。选取SD大鼠15只,简单随机法分为3组:第1组于大鼠右侧尾状核移植未标记的NSCs,第2组于大鼠右侧尾状核移植标记的NSCs,第3组右侧尾状核移植游离的SPIO颗粒,移植后第1、4、8周进行MRI。8周后处死大鼠,行组织切片普鲁士兰染色。结果:体外标记的神经干细胞普鲁士兰染色发现铁颗粒聚集于细胞浆内,标记率为100%;标记细胞与未标记细胞的台盼兰染色结果无显著差异。移植后MRI,第1组注射点未见低信号影;第2组注射点T2WI及GRE序列均可见类圆形低信号影;第3组大鼠注射后1周注射点可见低信号影,4周后低信号影变淡且边缘变模糊,8周后低信号影T2WI已不明显。与T2WI序列比较,GRE序列显示标记细胞更清晰,但显示范围较扩散。脑组织切片的普鲁士兰染色显示,第1组大鼠脑组织切片未见异常蓝染细胞,第2组注射点可见蓝染细胞,第3组注射点可见稍许散在蓝色颗粒状物质。结论:多聚左旋赖氨酸介导下SPIO可用于标记神经干细胞,标记细胞移植后MRI可以无创性观察移植神经干细胞的位置及分布情况。

Magnetic Resonance Tracking of Magnetically Labeled Rat Embryonic Neural Stem Cells after Transplantation

Objective:To explore the methods of labeling neural stem cells(NSCs) with superparamagnetic iron oxide(SPIO) particles,and to monitor the labeled cells after transplantation into the rat with MR scanning.(Methods:)Neural stem cells,labeled with SPIO mediated by poly-L-lysine,underwent Trypan blue staining to observe cell viability of the labeled cells and Prussian blue staining to evaluate the labeling rate.Fifteen rats were divided into three groups in random: the(unlabeled) and labeled NSCs,and free SPIO particles were transplanted into the right caudate nucleus respectively.MR(scanning) was performed to monitor the transplanted cells after 1,4,8 weeks.After MR imaging,the rats were killed and underwent Prussian blue staining of the histological section.Results:Prussian blue staining of the cells showed numerous blue stained particles in the cytoplasm of the labeled cells.There was no significant difference between the results of Trypan blue staining in labeled and unlabeled cells.The MR imaging showed significant hypointensity in the transplanted areas after 1,4,8 weeks in the group of transplantation of the labeled cells.No any abnormal low signal intensity was observed in the rats of transplantation of the unlabeled cells.For free SPIO particle group,hypointensity also could be observed after 4 weeks,but the T_(2) relaxation time was prolonged,and after 8 weeks,the low signal intensity became blurred.The Prussian blue(staining) of the perfused tissue showed numerous blue stained cells in the right caudate nucleus,which was the same area with the MR imaging.Conclusion:Poly-L-lysine mediated SPIO can be used to label NSCs,and MR scanning is useful in tracking the location and distribution of the labeled neural stem cells after transplantation.