诱导后大鼠胰岛素分泌细胞超顺磁化氧化铁颗粒-多聚左旋赖氨酸体外标记后生物活性研究

Characterization of biophysical properties of insulin-producing cells labeled with SPIO-PLL in vitro

目的比较超顺磁化氧化铁颗粒-多聚左旋赖氨酸(SPIO-PLL)标记与未标记诱导后大鼠胰岛素分泌细胞的生物活性,探讨两者MRI成像表现。方法分离培养大鼠骨髓间质干细胞(BMSC),经二期方案诱导成胰岛素分泌细胞,SPIO-PLL标记细胞,普鲁士蓝染色显示细胞内铁;放射免疫分析法测定标记及未标记细胞的胰岛素分泌情况;同时采用临床应用型1．5 T MR仪对两组细胞群进行T_1WI、T_2WI、T_2*WI 3个序列成像。结果普鲁士蓝染色显示标记细胞蓝色铁颗粒位于细胞内。标记后的细胞能分泌胰岛素,经统计学分析分泌量与未标记细胞无显著性差异。标记后的细胞在以T_2*WI序列信号降低最明显,信号强度变化率最大。结论SPIO-PLL可以有效标记诱导后大鼠胰岛素分泌细胞,且对其生物学活性无明显影响,临床应用型1．5 T MR仪可对标记细胞群进行体外成像。

Objective To evaluate the biophysical properties of insulin-producing cells labeled and unlabeled with superparamagnetic iron oxide nanoparticals and poly-L-lysine （SPIO-PLL） in vitro, and then monitor cellular imaging with 1.5 T MR. Methods BMSCs were isolated from tibia and femur of 6～8 weeks normal Sprague-Dawley rats, purified on the basis of their ability to adhere to the matrix, and expanded through their self-renewal. Two-step strategy was adopted with BMSCs induced into insulin-producing cells. After that, the cells were incubated with SPIO-PLL. Prussian blue stain was employed for identifying intracellular irons. Radioimmunology assay was used to measure the insulin secretion by the labeled and unlabeled cells, and later on underwent MR imaging with T1WI、T2WI、T2＊WI sequences. Results Intracytoplasmic nanoparticales were stained with Prussian blue possessing insulin-producing cells labeled with SPIO-PLL. The amount of insulin secreted by the labeled and unlabeled cells had no statistical significant difference. The signal intensity of labeled cells decreased significantly on T2＊WI, as well as the stronger proportional variations for signal intensity. Conclusion Insulin-producing cells can be labelled effectively with SPIO-PLL and be imaged by 1.5 T MRI.