超顺磁性氧化铁标记小鼠淋巴细胞MR成像特性探讨

目的探讨超顺磁性氧化铁（SPIO）标记小鼠脾脏淋巴细胞及其体外MR成像的可行性。方法取5只小鼠脾脏淋巴细胞，采用100、50、25、15、10、5μg/ml的SPIO联合3μg／ml的多聚赖氨酸（PLL）标记淋巴细胞，确定最佳标记浓度。普鲁士蓝染色鉴定细胞内铁。取30份新鲜、标记、未标记淋巴细胞行台盼蓝染色检测细胞存活率的变化。用对照组及2×10^6、5×10^6和10×10^6个／ml的标记后淋巴细胞接种于琼脂糖凝胶中行3．0TMRT：WI、T2WI及磁敏感加权成像（SWI）序列扫描，相同细胞浓度不同序列及相同序列不同细胞浓度时各取21个感兴趣区测量MR信号值。采用组间独立样本t检验比较细胞存活率；单因素方差分析比较MR信号值差异。结果SPIO联合PLL成功标记小鼠淋巴细胞，最佳SPIO浓度为5μg／ml。普鲁士蓝染色显示细胞内存在蓝染铁颗粒，阳性率为（93．6±2．1）％。30份台盼蓝染色细胞样本，新鲜分离的淋巴细胞存活率为（94．8±3．1）％，细胞培养6h后，标记组和未标记组淋巴细胞存活率分别为（88．7±2．7）％和（88．9±3．2）％。标记组同未标记组细胞间存活率差异无统计学意义（t=0．281，P〉0．05），但标记组、未标记组存活率同培养前相比，其下降均有统计学意义（t值分别为8．125、7．253，P值均〈0．05）。相同浓度细胞，T2WI信号降低最弱，SWI信号降低最明显。结论SPIO联合PLL能有效标记小鼠淋巴细胞，且不影响其存活率，标记细胞体外3．0TMR成像可行，以SWI序列最敏感。

Objective To investigate the feasibility of labeling mice spleen lymphocytes with superparamagnetic iron oxide(SPIO)and in vitro MR imaging of the labeled cells.Methods Spleen lymphocytes of 5 mice were isolated and then labeled with SPIO of 100,50,25,15,10,5 μg/ml,which was previously prepared with PLL.Prussian blue staining was performed to show the intracellular iron.Cell viability was compared among fresh,labeled and unlabeled cells.Different concentrations of mice spleen lymphocytes were screened using 3.0 T MR on T2WI,T2 * WI and SWI sequences in vitro.Cell viability was compared using independent-sample t test between groups.The MRI values among different groups were compared using one-way ANOVA.Results SPIO prepared with PLL could successfully label mice spleen lymphocytes,the optimum concentration of SPIO was 5 μg/ml.The Prussian blue staining showed intracellular blue spots and a labeling efficiency of(93.6 ± 2.1)％.Three groups of fresh,labeled and unlabeled cells showed a Trypan blue staining result of(94.8 ± 3.1)％,(88.7 ± 2.7)％,and(88.9 ±3.2)％,respectively; no statistically significant difference was found in cell viability between labeled and unlabeled lymphocytes(t =0.281,P ＞ 0.05); however,the cell viability of fresh cells were statistically significant higher than the labeled and unlabeled lymphocytes(t =8.125 and 7.253 respectively,P ＜0.05for all).Among the T2 WI,T2 * WI and SWI sequences under the same concentrations of cells,the SWI sequence was the most sensitive.Conclusions The mice spleen lymphocytes can be effectively labeled with SPIO with no impact on cell viability,and MR can be used to track these labeled cells in vitro.The SWI sequence is the most sensitive.