Williams John B, Ye Qing, Hitchens T Kevin, Kaufman Christina L, Ho Chien
Pittsburgh NMR Center for Biomedical Research, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
J Magn Reson Imaging. 2007 Jun;25(6):1210-8. doi: 10.1002/jmri.20930.
To evaluate cellular labeling of immune cells using micron-sized iron oxide particles (MPIOs) and evaluate the MR relaxivity and MRI detection of the labeled cells.
Immune cells isolated from mice and rats were labeled with three different sizes of MPIO particles (0.35, 0.90, or 1.63 microm). These labeled cells were characterized using transmission electron microscopy (TEM), fluorescence microscopy, flow cytometry, MR relaxometry, and MRI.
Macrophage uptake of MPIOs was found to be highest for the 1.63-microm size particles. MR relaxivity measurements indicated greater spin-spin relaxation for MPIO-labeled cells relative to cells labeled with nanometer-sized ultra-small superparamagnetic iron oxide (USPIO) particles with similar iron content. TEM and fluorescence microscopy indicated cellular uptake of multiple MPIO particles per cell. Macrophages labeled with 1.63-microm MPIOs had an average cellular iron uptake of 39.1 pg/cell, corresponding to approximately 35 particles per cell.
Cells labeled with one or more MPIO particles could be readily detected ex vivo at 11.7 Tesla and after infusion of the MPIO-labeled macrophages into the kidney of a rat, hypointense regions of the outer cortex are observed, in vivo, by MRI at 4.7 Tesla.
评估使用微米级氧化铁颗粒（MPIOs）对免疫细胞进行细胞标记，并评估标记细胞的磁共振弛豫率和MRI检测情况。
从小鼠和大鼠中分离出的免疫细胞用三种不同大小的MPIO颗粒（0.35、0.90或1.63微米）进行标记。使用透射电子显微镜（TEM）、荧光显微镜、流式细胞术、磁共振弛豫测量法和MRI对这些标记细胞进行表征。
发现巨噬细胞对1.63微米大小颗粒的MPIO摄取量最高。磁共振弛豫率测量表明，相对于用具有相似铁含量的纳米级超小超顺磁性氧化铁（USPIO）颗粒标记的细胞，MPIO标记的细胞具有更大的自旋-自旋弛豫。TEM和荧光显微镜显示每个细胞摄取多个MPIO颗粒。用1.63微米MPIO标记的巨噬细胞平均细胞铁摄取量为39.1皮克/细胞，相当于每个细胞约35个颗粒。
在11.7特斯拉下可以很容易地在体外检测到用一个或多个MPIO颗粒标记的细胞，并且在将MPIO标记的巨噬细胞注入大鼠肾脏后，在4.7特斯拉的MRI下可以在体内观察到肾外皮质的低信号区域。
