Schäfer Richard, Kehlbach Rainer, Wiskirchen Jakub, Bantleon Rüdiger, Pintaske Jörg, Brehm Bernhard R, Gerber Annika, Wolburg Hartwig, Claussen Claus D, Northoff Hinnak
Institute of Clinical and Experimental Transfusion Medicine, University Medical Center Tübingen, Hoppe-Seyler-Str 3, D-72076 Tübingen, Germany.
Radiology. 2007 Aug;244(2):514-23. doi: 10.1148/radiol.2442060599. Epub 2007 Jun 11.
To prospectively evaluate the influence of superparamagnetic iron oxide (SPIO) or ultrasmall SPIO (USPIO) particles on the surface epitope pattern of adult mesenchymal stem cells (MSCs) by regulating the expression of transferrin receptor and to prospectively evaluate the influence of transfection agents (TAs) on the uptake of SPIO or USPIO particles in MSCs.
The study was approved by the institutional animal care committee of the University of Tübingen. MSCs were isolated from the bone marrow of four rats. To obtain highly homogeneous MSC populations, MSCs from one rat were single-cell cloned. One MSC clone was characterized and selected for the labeling experiments. The MSCs, which were characterized with flow cytometry and in vitro differentiation, were labeled with 200 microg/mL SPIO or USPIO or with 60 microg/mL SPIO or USPIO in combination with TAs. Aggregations of labeled cells were accommodated inside a defined volume in an agar gel matrix. Magnetic resonance (MR) imaging was performed to measure SPIO- or USPIO-induced signal voids. Quantification of cellular total iron load (TIL) (intracellular iron plus iron coating the cellular surface), determination of cellular viability, and electron microscopy were also performed.
Labeling of MSCs with SPIO or USPIO was feasible without affecting cell viability (91.1%-94.7%) or differentiation potential. For MR imaging, SPIO plus a TA was most effective, depicting 5000 cells with an average TIL of 76.5 pg per cell. SPIO or USPIO particles in combination with TAs coated the cellular surface but were not incorporated into cells. In nontransfected cells, SPIO or USPIO was taken up. MSCs labeled with SPIO or USPIO but without a TA showed enhanced expression of transferrin receptor, in contrary to both MSCs labeled with SPIO or USPIO and a TA and control cells.
SPIO or USPIO labeling without TAs has an influence on gene expression of MSCs upregulating transferrin receptor. Furthermore, SPIO labeling with a TA will coat the cellular surface.
通过调节转铁蛋白受体的表达，前瞻性评估超顺磁性氧化铁（SPIO）或超小超顺磁性氧化铁（USPIO）颗粒对成人骨髓间充质干细胞（MSC）表面表位模式的影响，并前瞻性评估转染试剂（TA）对MSC摄取SPIO或USPIO颗粒的影响。
本研究经图宾根大学机构动物护理委员会批准。从4只大鼠的骨髓中分离出MSC。为获得高度均匀的MSC群体，对来自1只大鼠的MSC进行单细胞克隆。对1个MSC克隆进行表征并选择用于标记实验。用流式细胞术和体外分化进行表征的MSC，用200μg/mL SPIO或USPIO或用60μg/mL SPIO或USPIO与TA联合标记。将标记细胞的聚集体容纳在琼脂凝胶基质的限定体积内。进行磁共振（MR）成像以测量SPIO或USPIO诱导的信号缺失。还进行了细胞总铁负荷（TIL）（细胞内铁加上覆盖细胞表面的铁）的定量、细胞活力的测定以及电子显微镜检查。
用SPIO或USPIO标记MSC是可行的，且不影响细胞活力（91.1% - 94.7%）或分化潜能。对于MR成像，SPIO加TA最有效，可描绘出5000个细胞，平均每个细胞的TIL为76.5 pg。SPIO或USPIO颗粒与TA联合包被细胞表面，但未被细胞摄取。在未转染的细胞中，SPIO或USPIO被摄取。与用SPIO或USPIO和TA标记的MSC以及对照细胞相反，用SPIO或USPIO但不用TA标记的MSC显示转铁蛋白受体表达增强。
不使用TA的SPIO或USPIO标记对上调转铁蛋白受体的MSC基因表达有影响。此外，用TA进行SPIO标记会包被细胞表面。
