Application of the static dephasing regime theory to superparamagnetic iron-oxide loaded cells
Application of the static dephasing regime theory to superparamagnetic iron-oxide loaded cells
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DOI：
10.1002/mrm.10192
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发表时间：
2002-07-01
影响因子：
3.3
通讯作者：
Rutt, BK
中科院分区：
文献类型：
--
作者：
Bowen, CV;Zhang, XW;Rutt, BK
研究了细胞内划分的氧化铁纳米颗粒的弛豫速率，发现其满足静态退相（SD）理论的预测。使用两种不同的氧化铁纳米颗粒（超顺磁性氧化铁（SPIO）和超小SPIO（USPIO）），以四种不同的铁浓度（0.05、0.1、0.2和0.3 mg/ml）和五种不同的孵育时间（6、12、24、36和48小时）加载细胞培养物中的THP-1细胞。使用新开发的成像版本的磁共振成像技术评估细胞的氧化铁摄取，发现其与剂量和孵育时间呈线性关系。发现R*（2）对负载氧化铁的细胞的灵敏度比R-2大70倍，比R-1大3100倍。这与均匀分布的纳米颗粒有很大不同，并且与细胞体磁化率（BMS）弛豫机制一致。细胞磁矩足够大，使得R '（2）弛豫率与所有测试的细胞样品的SD状态理论预测密切一致[R'（2）= 2 pi/（9 root 3）（.）其中局部磁剂量（LVID）是由于氧化铁颗粒的存在而导致的样品磁化）。SPIO和USPIO的均匀悬浮液产生的R '（2）弛豫率分别比SD区理论预测的小3倍和8倍。这些结果是一致的理论估计所需的质量铁每隔室需要保证SD制度占主导地位的弛豫。对于细胞样品，R-2被证明依赖于氧化铁颗粒的浓度和分布，而R '（2）仅对氧化铁浓度敏感。这项工作是量化细胞铁含量并最终绘制目标细胞群密度的重要第一步。(C)2002 Wiley-Liss，Inc.
The relaxation rates of iron-oxide nanoparticles compartmentalized within cells were studied and found to satisfy predictions of the static dephasing (SD) regime theory. THP-1 cells in cell culture were loaded using two different iron-oxide nanoparticles (superparamagnetic iron-oxide (SPIO) and ultrasmall SPIO (USPIO) with four different iron concentrations (0.05, 0.1, 0.2, and 0.3 mg/ml) and for five different incubation times (6,12, 24, 36, and 48 hr). Cellular iron-oxide uptake was assessed using a newly developed imaging version of MR susceptometry, and was found to be linear with both dose and incubation time. R*(2) sensitivity to iron-oxide loaded cells was found to be 70 times greater than for R-2, and 3100 times greater than for R-1. This differs greatly from uniformly distributed nanoparticles and is consistent with a cellular bulk magnetic susceptibility (BMS) relaxation mechanism. The cellular magnetic moment was large enough that R'(2) relaxivity agreed closely with SD regime theory predictions for all cell samples tested [R'(2) = 2pi/(9root3) (.) gammaLMD] where the local magnetic dose (LIVID) is the sample magnetization due to the presence of iron-oxide particles). Uniform suspensions of SPIO and USPIO produced R'(2) relaxivities that were a factor of 3 and 8 less, respectively, than SD regime theory predictions. These results are consistent with theoretical estimates of the required mass of iron per compartment needed to guarantee SD-regime-dominant relaxivity. For cellular samples, R-2 was shown to be dependent on both the concentration and distribution of iron-oxide particles, while R'(2) was sensitive to iron-oxide concentration alone. This work is an important first step in quantifying cellular iron content and ultimately mapping the density of a targeted cell population. (C) 2002 Wiley-Liss, Inc.