Terrovitis John V, Bulte Jeff W M, Sarvananthan Sajiram, Crowe Lindsey A, Sarathchandra Padmini, Batten Puspa, Sachlos Eleftherios, Chester Adrian H, Czernuszka Jan T, Firmin David N, Taylor Patricia M, Yacoub Magdi H
Heart Science Centre, Harefield Hospital, Imperial College, London, United Kingdom.
Tissue Eng. 2006 Oct;12(10):2765-75. doi: 10.1089/ten.2006.12.2765.
Mesenchymal stem cells (MSCs) are a promising candidate cell for tissue engineering. Magnetic resonance imaging (MRI) has been proven effective in visualizing iron-labeled stem cells; however, the efficiency of this approach for visualization of cells seeded on scaffolds intended for use as tissue-engineered heart valves has not been assessed. MSCs were labeled by incubating for 48 h with ferumoxide and poly-L-lysine as transfecting agent. Any detrimental effect of iron labeling on cell viability, proliferation, and differentiation was examined using appropriate functional assays. Change in the nuclear magnetic relaxation properties of labeled cells was determined using in vitro relaxometry of cells seeded in 3-dimensional collagen gels. Images of labeled and non-labeled cells seeded onto 1% type I bovine collagen scaffolds were obtained using MRI. The presence of intracellular iron in labeled cells was demonstrated using Prussian blue staining, confocal microscopy, and electron microscopy. Cell viability, proliferation, and differentiation were comparable in labeled and non-labeled cells. The T2 relaxation time was 40% to 50% shorter in ferumoxide-labeled cells. Labeled cells seeded on scaffolds appeared as areas of reduced signal intensity in T2 weighted images. Ferumoxide labeling persisted and remained effective even on scans performed 4 weeks after the labeling procedure. Ferumoxide labeling of human MSCs seeded on collagen scaffolds is an effective, non-toxic technique for visualization of these cells using MRI. This technique appears promising for cell tracking in future tissue-engineering applications.
间充质干细胞（MSCs）是组织工程中一种很有前景的候选细胞。磁共振成像（MRI）已被证明在可视化铁标记的干细胞方面有效；然而，这种方法用于可视化接种在用作组织工程心脏瓣膜的支架上的细胞的效率尚未得到评估。通过用铁氧化物和聚-L-赖氨酸作为转染剂孵育48小时来标记MSCs。使用适当的功能测定法检查铁标记对细胞活力、增殖和分化的任何有害影响。使用接种在三维胶原凝胶中的细胞的体外弛豫测量法测定标记细胞的核磁弛豫特性的变化。使用MRI获得接种在1% I型牛胶原支架上的标记细胞和未标记细胞的图像。使用普鲁士蓝染色、共聚焦显微镜和电子显微镜证明标记细胞中存在细胞内铁。标记细胞和未标记细胞的细胞活力、增殖和分化相当。铁氧化物标记的细胞的T2弛豫时间缩短了40%至50%。接种在支架上的标记细胞在T2加权图像中表现为信号强度降低的区域。即使在标记程序后4周进行的扫描中，铁氧化物标记仍然持续且有效。接种在胶原支架上的人MSCs的铁氧化物标记是一种使用MRI可视化这些细胞的有效、无毒技术。这种技术在未来的组织工程应用中用于细胞追踪似乎很有前景。
