Hill Jonathan M, Dick Alexander J, Raman Venkatesh K, Thompson Richard B, Yu Zu-Xi, Hinds K Allison, Pessanha Breno S S, Guttman Michael A, Varney Timothy R, Martin Bradley J, Dunbar Cynthia E, McVeigh Elliot R, Lederman Robert J
Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10, Room 2c713, Bethesda, MD 20892-1538, USA.
Circulation. 2003 Aug 26;108(8):1009-14. doi: 10.1161/01.CIR.0000084537.66419.7A. Epub 2003 Aug 11.
Delivery and tracking of endomyocardial stem cells are limited by the inability to image transplanted cells noninvasively in the beating heart. We hypothesized that mesenchymal stem cells (MSCs) could be labeled with a iron fluorophore particle (IFP) to provide MRI contrast in vivo to assess immediate and long-term localization.
MSCs were isolated from swine. Short-term incubation of MSCs with IFP resulted in dose-dependent and efficient labeling. Labeled cells remained viable for multiple passages and retained in vitro proliferation and differentiation capacity. Labeled MSCs (10(4) to 10(6) cells/150 microL) were injected percutaneously into normal and freshly infarcted myocardium in swine. One, 3, and 1 animals underwent serial cardiac MRI (1.5T) for 4, 8, and 21 days, respectively. MRI contrast properties were measured both in vivo and in vitro for cells embedded in agar. Injection sites containing as few as 10(5) MSCs could be detected and contained intact IFP-bearing MSCs on histology.
IFP labeling of MSCs imparts useful MRI contrast, enabling ready detection in the beating heart on a conventional cardiac MR scanner after transplantation into normal and infarcted myocardium. The dual-labeled MSCs can be identified at locations corresponding to injection sites, both ex vivo using fluorescence microscopy and in vivo using susceptibility contrast on MRI. This technology may permit effective in vivo study of stem cell retention, engraftment, and migration.
心肌内膜干细胞的递送和追踪受到无法在跳动的心脏中对移植细胞进行无创成像的限制。我们假设间充质干细胞（MSCs）可以用铁荧光团颗粒（IFP）标记，以在体内提供MRI对比，从而评估其即时和长期定位。
从猪中分离出MSCs。将MSCs与IFP进行短期孵育可实现剂量依赖性的有效标记。标记后的细胞在多次传代后仍保持活力，并保留体外增殖和分化能力。将标记的MSCs（10⁴至10⁶个细胞/150微升）经皮注射到猪的正常和新鲜梗死心肌中。分别有1只、3只和1只动物在第4天、第8天和第21天接受了系列心脏MRI（1.5T）检查。对琼脂包埋的细胞在体内和体外均测量了MRI对比特性。含有低至10⁵个MSCs的注射部位均可被检测到，并且组织学检查显示含有完整的携带IFP的MSCs。
MSCs的IFP标记赋予了有用的MRI对比，使得在移植到正常和梗死心肌后，能够在传统心脏MR扫描仪上轻易地检测到跳动心脏中的MSCs。双标记的MSCs可以在与注射部位相对应的位置被识别，在体外使用荧光显微镜，在体内使用MRI的敏感性对比。这项技术可能允许有效地在体内研究干细胞的滞留、植入和迁移。
