Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada.
Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada ; Department of Medical Biophysics, University of Western Ontario, London, ON, Canada.
Int J Nanomedicine. 2014 Apr 8;9:1731-9. doi: 10.2147/IJN.S59127. eCollection 2014.
Mesenchymal stem cells (MSC) are used to restore deteriorated cell environments. There is a need to specifically track these cells following transplantation in order to evaluate different methods of implantation, to follow their migration within the body, and to quantify their accumulation at the target. Cellular magnetic resonance imaging (MRI) using fluorine-based nanoemulsions is a great means to detect these transplanted cells in vivo because of the high specificity for fluorine detection and the capability for precise quantification. This technique, however, has low sensitivity, necessitating improvement in MR sequences. To counteract this issue, the balanced steady-state free precession (bSSFP) imaging sequence can be of great interest due to the high signal-to-noise ratio (SNR). Furthermore, it can be applied to obtain 3D images within short acquisition times. In this paper, bSSFP provided accurate quantification of samples of the perfluorocarbon Cell Sense-labeled cells in vitro. Cell Sense was internalized by human MSC (hMSC) without adverse alterations in cell viability or differentiation into adipocytes/osteocytes. The bSSFP sequence was applied in vivo to track and quantify the signals from both Cell Sense-labeled and iron-labeled hMSC after intramuscular implantation. The fluorine signal was observed to decrease faster and more significantly than the volume of iron-associated voids, which points to the advantage of quantifying the fluorine signal and the complexity of quantifying signal loss due to iron.
间充质干细胞（MSC）被用于修复受损的细胞环境。为了评估不同的移植方法，跟踪这些细胞在移植后的情况，观察它们在体内的迁移情况，并定量它们在靶部位的积累情况，需要专门对这些细胞进行跟踪。基于氟的纳米乳液的细胞磁共振成像（MRI）是一种在体内检测这些移植细胞的好方法，因为它对氟的检测具有高度特异性，并且能够进行精确的定量。然而，该技术的灵敏度较低，需要改进磁共振序列。为了解决这个问题，平衡稳态自由进动（bSSFP）成像序列可能非常有趣，因为它具有高信噪比（SNR）。此外，它可以应用于在短采集时间内获得 3D 图像。在本文中，bSSFP 对体外经全氟碳 Cell Sense 标记的细胞样本进行了准确的定量。Cell Sense 被人骨髓间充质干细胞（hMSC）内化，而不会对细胞活力或向成脂细胞/成骨细胞分化产生不利影响。该 bSSFP 序列被应用于体内，以跟踪和定量经肌肉内植入后来自 Cell Sense 标记和铁标记的 hMSC 的信号。观察到氟信号的下降速度比铁相关的空洞体积更快且更显著，这表明量化氟信号的优势以及量化由于铁导致的信号损失的复杂性。
