MRI to detect atherosclerosis with gadolinium-containing immunomicelles targeting the macrophage scavenger receptor.

The ability to specifically image macrophages may enable improved detection and characterization of atherosclerosis. In this study we evaluated the in vitro uptake of gadolinium (Gd)-containing immunomicelles (micelles linked to macrophage-specific antibody), micelles, and standard contrast agents by murine macrophages, and sought to determine whether immunomicelles and micelles improve ex vivo imaging of apolipoprotein E knockout (ApoE KO) murine atherosclerosis. Murine RAW 264.7 macrophages were incubated with Gd-DTPA, micelles, and immunomicelles. Cell pellets were prepared and imaged using a 1.5 T MR system with an inversion recovery spin-echo sequence to determine the in vitro T1 values. Ex vivo analysis of mouse aortas was performed using a 9.4T MR system with a high-spatial-resolution sequence (78x39x78 microm3). The T1 value was significantly decreased in cells treated with micelles compared to Gd-DTPA (P<0.0001), and in cells incubated at 4 degrees C with immunomicelles compared to micelles (P<0.05). Ex vivo MRI signal intensity (SI) was significantly increased by 81% and 20% in aortas incubated with immunomicelles and micelles, respectively. Confocal microscopy demonstrated in vitro and ex vivo uptake of fluorescent immunomicelles by macrophages. Immunomicelles and micelles improve in vitro and ex vivo MR detection of macrophages, and may prove useful in the detection of macrophage-rich plaques.     

Chemodosimetry of in vivo tumor liposomal drug concentration using MRI.

Effective cancer chemotherapy depends on the delivery of therapeutic drugs to cancer cells at cytotoxic concentrations. However, physiologic barriers, such as variable vessel permeability, high interstitial fluid pressure, and heterogeneous perfusion, make it difficult to achieve that goal. Efforts to improve drug delivery have been limited by the lack of noninvasive tools to evaluate intratumoral drug concentration and distribution. Here we demonstrate that tumor drug concentration can be measured in vivo using T(1)-weighted MRI, following systemic administration of liposomes containing both drug (doxorubicin (DOX)) and contrast agent (manganese (Mn)). Mn and DOX concentrations were calculated using T(1) relaxation times and Mn:DOX loading ratios, as previously described. Two independent validations by high-performance liquid chromatography (HPLC) and histologic fluorescence in a rat fibrosarcoma (FSA) model indicate a concordant linear relationship between DOX concentrations determined using T(1) and those measured invasively. This method of imaging exhibits potential for real-time evaluation of chemotherapeutic protocols and prediction of tumor response on an individual patient basis.     

叶酸受体介导的肿瘤靶向超顺磁性纳米胶束的制备及体外实验

目的探讨叶酸受体介导的两亲聚合物纳米胶束对人肝癌Bel 7402细胞的靶向性，及利用MR仪对其进行监测的可行性。方法制备由叶酸修饰的、载有超顺磁性氧化铁（SPIO）及抗癌药物表阿霉素（DOX）的纳米胶束，将叶酸靶向及非叶酸靶向纳米胶束分别与人肝癌Bel 7402细胞共孵育1h，进行普鲁士蓝染色和流式细胞术观察Bel 7402细胞对叶酸靶向及非叶酸靶向纳米胶束的吸收情况，并体外MRI观察T2WI信号强度变化。结果叶酸靶向纳米胶束与Bel 7402细胞共孵育后普鲁士蓝染色显示细胞内大量铁存在；非叶酸靶向纳米胶束普鲁士蓝染色显示细胞内铁浓度极低。流式细胞术显示叶酸靶向组及非叶酸靶向组的平均荧光强度分别为117．88和46．33，叶酸靶向组约为非叶酸靶向组的2．5倍。体外MRI显示叶酸靶向纳米胶束与Bel 7402细胞共孵育后在T2WI上信号明显降低（SPIO浓度为5、10、20、40和80μg／ml时，信号变化率中位数分别为-5．02％、-23．58％、-45．89％、-70．34％和-92．41％），而非叶酸靶向组在T2WI上信号无明显降低（SPIO浓度为5、10、20、40和80μg／ml时信号变化率中位数分别为-3．77％、-2．16％、-2．18％、-2．74％和-19．77％）。体外竞争抑制实验普鲁士蓝染色显示细胞内铁浓度极低。结论以叶酸修饰的生物可降解聚合物纳米胶束对人肝癌细胞Bel 7402有较好的靶向性，使用临床型MR仪可对其进行监测。     

小鼠移植瘤模型对SPIO增强MRI信号变化原因的初步研究

目的建立小白鼠肝脏原位移植瘤模型,初步探讨临床上影响肝癌超顺磁性氧化铁(SP10)增强MRI信号变化的因素。资料与方法(1)对25例肝病患者行SP10增强MRI扫描的临床、影像及病理学相关资料进行分析;(2)给小白鼠注射H-22肝癌细胞建立肝脏原位移植瘤模型40只;(3)成瘤后给小鼠进行MRI平扫及SP10增强扫描;(4)所有的瘤鼠做HE及普鲁士蓝铁染色并进行相关病理学分析。结果(1)25例患者中经病理证实为原发性肝癌2例、海绵状血管瘤1例及肝硬化结节1例,DSA及介入治疗有典型肝癌表现者2例。(2)肝脏移植瘤组在SP10增强后的T2WI上有10个移植瘤的信号未见下降;普鲁士蓝铁染色3只瘤鼠的瘤灶呈阳性,内见枯否细胞;7个瘤灶与肝组织明显呈浸润生长。结论SP10能提高肝脏占位性病变定性诊断率,但存在SP10增强MRI信号变化与病理机制不相符的现象;在少数纯瘤株移植瘤结节内及周边可见枯否细胞,成为影响肝癌的SP10增强MRI信号变化的重要原因;移植瘤的生长方式成为影响肿瘤的SP10增强后信号变化的相关因素。     

In vivo cellular imaging of lymphocyte trafficking by MRI: a tumor model approach to cell-based anticancer therapy.

The aim of this study was to demonstrate the feasibility of in vivo cell tracking to monitor anticancer cell therapy by means of a high-resolution noninvasive MRI method. Ovalbumin-specific splenocytes (OT-1) labeled with anionic gamma-Fe2O3 superparamagnetic iron oxide (SPIO) nanoparticles were adoptively transferred into C57BL/6 mice with growing ovalbumin-expressing tumors. OT-1 cells were tracked in vivo by 7 T MRI 24, 48, and 72 hr after they were injected. The results showed significant negative enhancement of the spleen at 24 hr, and of the tumor at 48 and 72 hr, after labeled cell injection. This suggests that the lymphocytes initially homed toward the spleen and were then recruited by the tumor. The presence of labeled cells was confirmed in ex vivo by 9.4 T microimaging of tumors and magnetic sorting of spleen cells. These results confirm that MR tracking of lymphocytes is feasible in vivo. This high-resolution imaging method could be used to improve the monitoring of immune cell therapy.     

Magnetic resonance imaging detects differences in migration between primary and immortalized neural stem cells

RATIONALE AND OBJECTIVES: The study was performed to evaluate the effect of magnetic resonance imaging (MRI) contrast agent (super paramagnetic iron oxide [SPIO]) on differentiation and migration of primary murine neural stem cells (NSCs) in comparison to a neural stem cell line (C17.2). Because detection of labeled cells depends on the concentration of SPIO particles per imaging voxel, the study was performed at various concentrations of SPIO particles to determine the concentration that could be used for in vivo detection of small clusters of grafted cells. MATERIALS AND METHODS: Murine primary NSCs or C17.2 cells were labeled with different concentrations of SPIO particles (0, 25, 100, and 250 mug Fe/mL) and in vitro assays were performed to assess cell differentiation. In vivo MRI was performed 7 weeks after neonatal transplantation of labeled cells to evaluate the difference in migration capability of the two cell populations. RESULTS: Both the primary NSCs and the C17.2 cells differentiated to similar number of neurons (Map2ab-positive cells). Similar patterns of engraftment of C17.2 cells were seen in transplanted mice regardless of the SPIO concentration used. In vivo MRI detection of grafted primary and C17.2 cells was only possible when cells were incubated with 100 mug/mL or higher concentration of SPIO. Extensive migration of C17.2 cells throughout the brain was observed, whereas the migration of the primary NSCs was more restricted. CONCLUSIONS: Engraftment of primary NSCs can be detected noninvasively by in vivo MRI, and the presence of SPIO particles do not affect the viability, differentiation, or engraftment pattern of the donor cells.     

家兔超急性期放射性肝损伤MRI表现与病理对照研究

目的　探讨超急性期放射性肝损伤MRI表现及其病理基础 ,评估MRI平扫及菲立磁增强扫描检出放射性肝损伤的时间效能。材料与方法　 18只家兔随机分成 3组后均给予 4 0Gy单次X线半肝照射 ,第 1组于照射后第1d、第 2、3组分别于照射后第 2、3d行肝区MRITSE T2 WI及TSE T1WI两个序列的平扫及菲立磁增强扫描 ,同时取材做组织学检查。对MRI表现与病理组织学检查结果进行对照分析。结果　所有家兔T2 WI及T1WI平扫、T1WI菲立磁增强扫描肝组织信号强度均未发现变化。T2 WI菲立磁增强扫描对放射性肝损伤的检出时间为照射后第 3d(P <0 .0 1) ,表现为肝组织信号强度受照区与非受照区均较T2 WI平扫时降低 ,但受照区肝组织信号强度较非受照区高 ,两者间可见分界线。所有家兔受照区肝组织在光镜下未见明确组织水肿、纤维化及炎症细胞浸润等病理征象 ,但其单位视野面积内含有SPIO颗粒的Kupffer细胞数在照射后第 3d明显低于非受照区 (P <0 .0 1)。电镜下 ,照射后第 3d的受照区肝细胞及Kupffer细胞内见线粒体明显肿胀伴局部空泡样变。结论　T2 WI菲立磁增强扫描在照射后短时间内 (照射后第 3d)即可检出超急性期放射性肝损伤 ,并能提供直观、精细的影像学依据     

Benign hepatic tumors: MRI features before and after administration of superparamagnetic contrast media

PURPOSE: To assess the yield of superparamagnetic iron oxide (SPIO)-enhanced MR images in the detection and characterization of benign hepatic tumors and to evaluate the potential role and safety of SPIO administration in the diagnosis of these tumors. MATERIAL AND METHODS: Eighteen patients underwent MRI before and after administration of SPIO particles. Spin echo (SE) T1, DP, T2 and Gradient echo (GE) T2* images were acquired with a.5 T superconductive unit. MR diagnosis was bioptically proved in 12 patients. In the remaining six patients, who had hemangiomas only, diagnosis was confirmed by at least two imaging techniques-such as MR, CT, ultrasonography, radio-labeled red cells scintigraphy-and by both clinical and imaging follow-up. RESULTS: Thirthy-four tumors were detected on the MR images: 29/34 (85,3%) before and 33/34 (97%) after SPIO administration - 6 focal nodular hyperplasias (FNH), 6 adenomas and 22 hemangiomas. One small tumor (adenoma) was detected on the unenhanced MR images only, while 4 lesions (3 adenomas, 1 FNH) were detected after SPIO administration only. DISCUSSION: SPIO-enhanced MRI increased the detection rate of benign hepatic tumors compared to non-enhanced MRI. Iron oxide was also useful in the characterization of such lesions as it was able to demonstrate any heterogeneity resulting from the presence of central scars or septa. Nevertheless, in our experience it was useful to compare baseline with SPIO-enhanced MRI, even if time consuming. Indeed the uptake of iron oxide particles by well-differentiated lesions and normal hepatic parenchyma, is comparable, so that well-differentiated lesions appear isointense and therefore undetectable. CONCLUSIONS: In our experience, although numerically limited, SPIO-enhanced MRI was clinically safe and more effective than non-enhanced MRI in both the detection and characterization of benign hepatic tumors, providing useful clues for diagnosis.     

荷人结肠癌裸鼠注射负载超顺磁性氧化铁聚合物纳米囊泡后的MRI表现

目的 制备负载油性超顺磁性氧化铁(SPIO)、水性SPIO聚合物纳米囊泡,并观察负载油性SPIO、水性SPIO聚合物纳米囊泡对结肠癌的MR显像能力.方法 通过多步化学反应制备聚乙二醇-聚D,L-丙交酯(PEG-PDLLA)纳米囊泡,并分别负载油性、水性SPIO.18只荷结肠癌裸鼠模型采用数字表法随机分为3组,每组6只,分别从尾静脉注射单纯SPIO水溶液、负载油性SPIO聚合物纳米囊泡和水性SPIO聚合物纳米囊泡,行MRI动态扫描观察肿瘤、肝脏、肌肉的T2WI信号和T2值.采用重复测量设计的方差分析比较3组间肿瘤、肝脏、肌肉的T2WI信号强度改变,两两比较采用Bonferroni法.结果 静脉注射负载油性、水性SPIO聚合物纳米囊泡后引起肿瘤T2WI信号强度下降,两者引起肿瘤信号强度下降最大百分比分别为11.00%、11.40%;单纯SPIO水溶液未能引起肿瘤信号强度下降,3组间比较差异有统计学意义(F=10.96,P＜0.01),负载油性、水性SPIO聚合物纳米囊泡引起的信号强度下降比单纯SPIO水溶液明显(P＜0.05);而负载油性和水性SPIO聚合物纳米囊泡间的差异无统计学意义(P＞0.05).3种对比剂均引起肝脏T2WI信号强度下降,单纯SPIO水溶液、负载油性、水性SPIO聚合物纳米囊泡引起肝脏信号强度下降的最大百分比分别为32.85%、52.77%、56.89%,3组间比较差异有统计学意义(F=161.18,P＜0.01),负载油性、水性SPIO聚合物纳米囊泡引起的信号强度下降比单纯SPIO水溶液明显(P＜0.01);负载水性SPIO聚合物纳米囊泡比负载油性SPIO聚合物纳米囊泡引起的信号强度下降更明显(P＜0.01).3种对比剂均未引起肌肉组织的T2WI信号强度下降,测量各组间肌肉的信号强度改变的差异无统计学意义(F=0.59,P＞0.05).结论 负载SPIO聚合物纳米囊泡在体内可以引起肿瘤的T2WI信号强度下降,可做为肿瘤显像的对比剂.

Abstract：

Objective To synthesize the hydrophobic supraparamagnetic ironic oxide(SPIO) loaded and hydrophilic SPIO loaded polymeric nano-vesicles and to investigate the feasibility of using hydrophobic SPIO loaded and hydrophilic SPIO loaded polymeric nano-vesicles to display the tumor in MRI in vivo through animal experiments. Methods The polymeric nano-vesicles were prepared from poly (D, L-lactic acid) (PDLLA) and poly (ethylene glycol) (PEG) by a multiple emulsion/solvent evaporation method.The hydrophobic SPIO and hydrophilic SPIO were loaded in the polymeric nano-vesicles respectively.Eighteen nude mice models with human colorectal carcinoma xenograft were established. They were divided equally into three groups (n = 6). The three groups of nude mice models were injected with water-soluble SPIO, hydrophobic SPIO loaded and hydrophilic SPIO loaded vesicle via the mice caudal vein respectively.Dynamic MRI scan were performed in all the mice models. T2WI signal intensity and T2 relaxation time were measured in the tumor, liver and muscle by using T2 mapping software. ANOVA of repeated measurement was used to analyze if there were significant differences of signal intensity changes among the three groups, while Bonferroni method was used for pair-wise comparison. Results On T2 WI, tumors showed decrease in signal intensity after hydrophobic or hydrophilic SPIO loaded polymeric nano-vesicle injection, while no signal intensity decrease was found in the tumor after water-soluble SPIO administration. The maximum percentage of signal intensity decrease in tumor caused by hydrophobic SPIO loaded and hydrophilic SPIO loaded vesicle were 11.00%, 11.40%, respectively. There was statistical significant difference of signal intensity changes among these three groups (F = 10. 96, P ＜ 0. 01). The decrease in signal intensity in the groups with hydrophilic or hydrophobic SPIO loaded polymeric nano-vesicles injection were more pronounced as compared with that of water-soluble SPIO (P ＜ 0. 05), but there was no significant difference in signal intensity decrease between the groups of hydrophilic and hydrophobic SPIO-loaded polymeric vesicles injection (P ＞0. 05). The three agents could lead to signal intensity decrease in the liver. The maximum percentage of signal intensity decrease in liver caused by water-soluble SPIO, hydrophobic SPIO loaded and hydrophilic SPIO loaded vesicle were 32. 85%, 52. 77%, 56. 89%, respectively. There was statistical significant difference between these groups (F = 161.18, P ＜ 0. 01) . The groups of injecting hydrophilic and hydrophobic SPIO loaded polymeric nano-vesicles had the more obvious signal decrease than the one with water-soluble SPIO (P ＜ 0. 01). Hydrophilic SPIO loaded polymeric nano-vesicles exhibited more signal intensity decrease than hydrophobic SPIO loaded polymeric nano-vesicles (P ＜ 0. 01). All three agents could not lead to T2WI signal decrease in the muscle, and there was no significant difference in signal change on T2 WI among three groups (F = 0. 59, P ＞ 0. 05). Conclusion SPIO loaded polymeric nano-vesicles can cause significant T2WI signal loss in human colonic carcinoma on MR imaging in vivo. It can be used as tumor imaging contrast agents.     

Cell motility of neural stem cells is reduced after SPIO‐labeling,which is mitigated after exocytosis

MRI is used for tracking of superparamagnetic iron oxide (SPIO)‐labeled neural stem cells. Studies have shown that long‐term MR tracking of rapidly dividing cells underestimates their migration distance. Time‐lapse microscopy of random cellular motility and cell division was performed to evaluate the effects of SPIO‐labeling on neural stem cell migration. Labeled cells divided symmetrically and exhibited no changes in cell viability, proliferation, or apoptosis. However, SPIO‐labeling resulted in decreased motility of neural stem cells as compared with unlabeled controls. When SPIO‐labeled neural stem cells and human induced pluripotent stem cells were transplanted into mouse brain, rapid exocytosis of SPIO by live cells was observed as early as 48 h postengraftment, with SPIO‐depleted cells showing the farthest migration distance. As label dilution is negligible at this early time point, we conclude that MRI underestimation of cell migration can also occur as a result of reduced cell motility, which appears to be mitigated following SPIO exocytosis. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

成簇成肌细胞的磁共振成像观察

目的:成肌细胞移植是治疗心功能不全的有效手段,磁共振成像(MRI)可以无创动态观测组织内移植细胞的分布及迁移增殖。本研究通过MRI观察超顺磁性氧化铁纳米粒子(SPIO)标记的成簇成肌细胞,探讨MRI应用价值。材料和方法:常规方法进行成肌细胞培养,应用脂质体包被的SPIO及DAPI双标记成肌细胞,通过MR及荧光显微镜观察标记的成簇成肌细胞。结果:普鲁士蓝染色证实了每个标记细胞胞质内有多少不等的蓝染铁颗粒,标记有效率为100%,通过MRI可以观察到标记的成簇成肌细胞呈现为黑点状影像,与荧光显微镜下所观察到的影像有一定对应性。结论:利用磁共振成像技术可以观察到成簇的细胞,为进一步利用磁共振对移植细胞活体无创追踪奠定了实验基础。     

Evaluation of super paramagnetic iron oxide-enhanced diffusion-weighted PROPELLER T2-fast spin echo magnetic resonance imaging: Preliminary experience

OBJECTIVE: To evaluate the usefulness of super paramagnetic iron oxide-enhanced, diffusion-weighted, periodically rotated overlapping parallel lines with enhanced reconstruction (SPIO DWI PROPELLER) T2-fast spin echo (FSE) magnetic resonance imaging (MRI) for the detection of hepatic metastases. METHODS: Fourteen patients were examined with SPIO-enhanced T2-FSE (SPIO FSE) imaging and SPIO DWI PROPELLER T2-FSE imaging. The b-value of the diffusion-sensitizing gradient was 10 s/mm so as to suppress the signal of the hepatic vessels. Hepatic resections were performed on all patients, and the number of lesions on MRI was compared between the 2 pulse sequences with references from pathologic reports. RESULTS: Nearly all metastases 1 cm or larger, totalling 38 metastases, were detected with both pulse sequences. Among the 30 metastases less than 1 cm, more lesions were detected on SPIO DWI PROPELLER T2-FSE imaging than on SPIO FSE imaging (16 for SPIO FSE imaging and 24 for DWI PROPELLER T2-FSE imaging; P < 0.05, McNemar test). CONCLUSION: Super paramagnetic iron oxide-enhanced DWI PROPELLER T2-FSE is useful for detecting small hepatic metastases.     

Usefulness of fat-suppressed T1-weighted MRI using orally administered superparamagnetic iron oxide for revealing ampullary carcinomas

OBJECTIVE: To evaluate the value of adding fat-suppressed (FS) T1-weighted magnetic resonance imaging (MRI) with orally administered superparamagnetic iron oxide (SPIO) to the 3-dimensional dynamic MRI for revealing ampullary carcinomas. MATERIALS: Twenty-five patients with ampullary carcinoma who underwent MRI with orally administered SPIO, including a FS T1-weighted fast low-angle shot (FLASH) sequence, a respiratory-triggered turbo spin-echo (RT-TSE) sequence, and the 3-phasic 3-dimensional dynamic images, were enrolled in this study. About 5 min before the examination, a mixture of 8.4 mg of SPIO and 300 mL water was administered orally to all patients. The images were compared quantitatively by measuring the tumor-pancreas (duodenum) contrast-to-noise ratio and, qualitatively, by evaluating tumor conspicuity. Three separate sets of images, that is, the dynamic set, the combination of the dynamic set, and the RT-TSE, and the combination of the dynamic set and the FLASH were analyzed by 2 observers in consensus. RESULTS: For the tumor-pancreas (duodenum) contrast-to-noise ratio, the FLASH was significantly higher than those of the dynamic set and RT-TSE (P < 0.05). The tumor conspicuity with the combination of the dynamic set and the FLASH was also significantly better than those of the dynamic set, and the combination of the dynamic set and RT-TSE (P = 0.001). For 15 tumors that were surgically confirmed, the combined reading of the FLASH imaging and dynamic set allowed more accurate surgical staging (14/15, 93.3%) than did the dynamic imaging set or the combined reading of the dynamic set and RT-TSE (11/15, 73.3%). CONCLUSIONS: Addition of the FS FLASH image using orally administered SPIO to the dynamic MRI is useful for revealing ampullary carcinoma.     

经聚乙烯亚胺钝化的荧光碳点负载阿霉素抑制非小细胞肺癌细胞增殖、迁移侵袭的治疗研究

目的研究利用经聚乙烯亚胺（PEI）钝化的荧光碳点（CD）装载阿霉素（DOX）进行药物递送，旨在增加DOX对非小细胞肺癌的治疗作用，减少DOX的心肌毒性。 方法通过一步微波加热法将甘油和PEI的混合物制备成CD-PEI，并通过静电效应将DOX装载至CD-PEI。采用CCK8实验检测CD-PEI-DOX对非小细胞肺癌细胞A549的增殖能力的影响；Transwell实验评估CD-PEI-DOX对A549细胞迁移侵袭能力的影响；最后通过体内动物实验评估CD-PEI-DOX的心肌毒性以及对非小细胞肺癌皮下肿瘤生长的抑制效果。 结果体外细胞实验证实，对比单纯的DOX处理组，CD-PEI-DOX对非小细胞肺癌A549细胞增殖、迁移侵袭能力的抑制作用更为显著。体内实验证实，CD-PEI-DOX纳米复合物治疗组小鼠心肌细胞结构完整，并且能有效抑制小鼠皮下肺癌肿瘤的生长。 结论经PEI钝化的荧光碳点负载阿霉素能显著提高DOX对非小细胞肺癌的治疗效果，并减少DOX对心脏的毒性作用。运用CD-PEI纳米颗粒改善化疗药物递送的治疗方案取得了初步证实，这可为肺癌化学治疗提供新思路，具有广大的临床应用前景。     

超急性期放射性肝损伤MRI菲立磁增强与照射剂量相关性研究

目的　探讨MRITSE -T2 WI菲立磁增强扫描对超急性期放射性肝损伤的诊断与评估价值。方法　 2 5只家兔随机分成 5组。除对照组外 ,其余 4组分别给予 10、2 0、3 0、40Gy单次X线半肝照射。照射后第 3天对肝区行MRITSE -T2 WI平扫及菲立磁增强扫描。分析辐照后肝组织损伤的强化特征 ,并进行组织学检查对照分析。结果　T2 WI菲立磁增强扫描在照射后第 3天能确切检出的放射性肝损伤的最小照射剂量为 3 0Gy(Ρ <0 .0 5 ) ,表现为受照区肝组织信号强度较非受照区高 ,两者间可见分界线。受照区肝组织菲立磁增强程度 (ER)的绝对值与照射剂量成正相关 (Ρ <0 .0 5 )。所有家兔受照区肝组织在光镜下未见明确组织水肿、纤维化及炎症细胞浸润等病理征象 ,但其单位视野面积内含有SPIO颗粒的Kupffer细胞数在≥ 2 0Gy组明显低于非受照区 (Ρ <0 .0 5 ) ,且与照射剂量成负相关 (Ρ <0 .0 5 )。结论　T2 WI菲立磁增强扫描不仅能早期发现 (照射后第 3天 )、明确诊断超急性期放射性肝损伤 ,还可通过测量肝组织ER对损伤程度进行估测。     

Magnetic nanoparticle labeling of mesenchymal stem cells without transfection agent: cellular behavior and capability of detection with clinical 1.5 T magnetic resonance at the single cell level.

The purpose of this work was to evaluate the efficacy of labeling human mesenchymal stem cells (hMSCs) by ionic superparamagnetic iron oxide (SPIO) without a transfection agent and verifying its capability to be detected with clinical 1.5 T magnetic resonance (MR) at the single-cell level. Human hMSCs were incubated for 24 h with an ionic SPIO, Ferucarbotran. The labeling efficiency of hMSCs was determined by iron content measurement spectrophotometrically, and the influence of labeling on cell behavior was ascertained by examination of cell viability using the trypan blue exclusion method, cell proliferation analysis using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, mitochondrial membrane potential (MMP) change, differentiation capacity, and reactive oxygen species (ROS) production measured by dichlorofluorescein diacetate (DCFDA) fluorescent probe. Labeled hMSCs were scanned under 1.5 T MRI with three-dimensional (3D) and two-dimensional (2D) T(2)-weighted gradient echo (GRE) pulse sequences. Human hMSC labeling without transfection agent was efficient. The iron content in hMSCs was 23.4 pg Fe/cell. No significant change was found in viability, proliferation, MMP change, ROS production, or differentiation capacity. About 45.2% of the hMSCs could be detected using 1.5 T MRI at the single cell level with 3D GRE and four repetitions.     

Physical and biological characterization of superparamagnetic iron oxide- and ultrasmall superparamagnetic iron oxide-labeled cells: a comparison

RATIONALE: Superparamagnetic iron-oxide particles are used frequently for cellular magnetic resonance imaging and in vivo cell tracking. The purpose of this study was to compare the labeling characteristics and efficiency as well as toxicity of superparamagnetic iron oxide (SPIO) and ultrasmall superparamagnetic iron oxide (USPIO) for 3 cell lines. METHODS: Using human fibroblasts, immortalized rat progenitor cells and HEP-G2-hepatoma cells, dose- and time-dependence of SPIO and USPIO uptake were evaluated. The amount of intracellular (U)SPIO was monitored over 2 weeks after incubation by T2-magnetic resonance relaxometry, ICP-mass-spectrometry, and histology. Transmission-electronmicroscopy was used to specify the intracellular localization of the endocytosed iron particles. Cell death-rate and proliferation-index were assessed as indicators of cell-toxicity. RESULT: For all cell lines, SPIO showed better uptake than USPIO, which was highest in HEP-G2 cells (110 +/- 2 pg Fe/cell). Cellular iron concentrations in progenitor cells and fibroblasts were 13 +/- 1pg Fe/cell and 7.2 +/- 0.3pg Fe/cell, respectively. For all cell lines T2-relaxation times in cell pellets were below detection threshold (<3 milliseconds) after 5 hours of incubation with SPIO (3.0 micromol Fe/mL growth medium) and continued to be near the detection for the next 6 days. For both particle types and all cell lines cellular iron oxide contents decreased after recultivation and surprisingly were found lower than in unlabeled control cells after 15 days. Viability and proliferation of (U)SPIO-labeled and unlabeled cells were not significantly different. CONCLUSIONS: The hematopoetic progenitor, mesenchymal fibroblast and epithelial HEP-G2 cell lines accumulated SPIO more efficiently than USPIO indicating SPIO to be better suited for cell labeling. However, the results indicate that there may be an induction of forced cellular iron elimination after incubation with (U)SPIO.     

Targeting Glut1-overexpressing MDA-MB-231 cells with 2-deoxy-D-g1ucose modified SPIOs

Glucose transporter (Glut), a cellular transmembrane receptor, plays a key role in cell glucose metabolism and is linked to a poor prognosis in various human cancers. In this study, we prepared γ-Fe(2)O(3) NPs coated with DMSA, in which modified with 2-DG, then γ-Fe(2)O(3)@DMSA-DG NPs was constructed. The specific interactions between Glut1-overexpressing tumor cells (MDA-MB-231) and γ-Fe(2)O(3)@DMSA-DG NPs were observed using Prussian blue staining and transmission electron microscope (TEM), and found that γ-Fe(2)O(3)@DMSA-DG NPs were absorbed targetedly by the cells. Furthermore, the capacity of transporting SPIOs into tumor cells using these γ-Fe(2)O(3)@DMSA-DG NPs was evaluated with a 1.5 T clinical magnetic resonance imaging (MRI) scanner. It was found that the acquired MRI T2 signal intensity of MDA-MB-231 cells that were treated with the γ-Fe(2)O(3)@DMSA-DG NPs decreased significantly, and it was inhibited by competition with antibody of Glut1. Our results suggest that γ-Fe(2)O(3)@DMSA-DG NPs are a useful targeting to Glut1-overexpressing tumor cells in vitro and that γ-Fe(2)O(3)@DMSA-DG NPs may serve as a MRI-targeted tumor agent for better tumor imaging.     

Depicting adoptive immunotherapy for prostate cancer in an animal model with magnetic resonance imaging

Genetically modified natural killer (NK) cells that recognize tumor‐associated surface antigens have recently shown promise as a novel approach for cancer immunotherapy. To determine NK cell therapy response early, a real‐time, noninvasive method to quantify NK cell homing to the tumor is desirable. The purpose of this study was to evaluate if MR imaging could provide a noninvasive, in vivo diagnosis of NK cell accumulation in epithelial cell adhesion molecule (EpCAM)‐positive prostate cancers in a rat xenograft model. Genetically engineered NK‐92‐scFv(MOC31)‐ζ cells, which express a chimeric antigen receptor specific to the tumor‐associated EpCAM antigen, and nontargeted NK‐92 cells were labeled with superparamagnetic particles of iron‐oxides (SPIO) ferumoxides. Twelve athymic rats with implanted EpCAM positive DU145 prostate cancers received intravenous injections of 1.5 × 10⁷ SPIO labeled NK‐92 and NK‐92‐scFv(MOC31)‐ζ cells. EpCAM‐positive prostate cancers demonstrated a progressive and a significant decline in contrast‐to‐noise‐ratio data at 1 and 24 h after injection of SPIO‐labeled NK‐92‐scFv(MOC31)‐ζ cells. Conversely, tumor contrast‐to‐noise‐ratio data did not change significantly after injection of SPIO‐labeled parental NK‐92 cells. Histopathology confirmed an accumulation of the genetically engineered NK‐92‐scFv(MOC31)‐ζ cells in prostate cancers. Thus, the presence or absence of a tumor accumulation of therapeutic NK cells can be monitored with cellular MR imaging. EpCAM‐directed, SPIO labeled NK‐92‐scFv(MOC31)‐ζ cells accumulate in EpCAM‐positive prostate cancers. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

Quantification of superparamagnetic iron oxide (SPIO)-labeled cells using MRI

PURPOSE: To show the feasibility of using magnetic resonance imaging (MRI) to quantify superparamagnetic iron oxide (SPIO)-labeled cells. MATERIALS AND METHODS: Lymphocytes and 9L rat gliosarcoma cells were labeled with ferumoxides-protamine sulfate complex (FE-PRO). The cells were labeled efficiently (more than 95%) and the iron concentration inside each cell was measured by spectrophotometry (4.77-30.21 pg). Phantom tubes containing different numbers of labeled or unlabeled cells, as well as different concentrations of FE-PRO, were made. In addition, labeled and unlabeled cells were injected into fresh and fixed rat brains. RESULTS: Cellular viability and proliferation of labeled and unlabeled cells were shown to be similar. T2-weighted images were acquired using 7T and 3T MRI systems, and R2 maps of the tubes containing cells, free FE-PRO, and brains were made. There was a strong linear correlation between R2 values and labeled cell numbers, but the regression lines were different for the lymphocytes and gliosarcoma cells. Similarly, there was strong correlation between R2 values and free iron. However, free iron had higher R2 values than the labeled cells for the same concentration of iron. CONCLUSION: Our data indicate that in vivo quantification of labeled cells can be done by careful consideration of different factors and specific control groups.