Feridex及Resovist对神经干细胞生物学特性影响的实验研究

目的研究超顺磁性氧化铁(superparamagnetic iron oxides,SPIOs)Feridex及Resovist对神经干细胞(neural stem cells,NSCs)生物学特性的影响。方法 NSCs培养及鉴定;使用Feridex及Resovist制备磁标记NSCs;利用免疫细胞化学、透射电镜和Prussian blue染色等方法对磁标记NSCs的生长、分化等生物学特性进行研究。结果 Feridex及Resovist分别与NSCs共同孵育后,透射电镜及Prussian blue染色显示胞浆中含有铁颗粒,SPIOs也可以随细胞的分裂增殖而传到子代细胞中。随Feridex及Resovist浓度的增高(2.8μg/mL～16.8μg/mL),Feridex及Resovist对NSCs存活、分化能力的影响无显著性差异(P>0.05)。当Feridex及Resovist的浓度大于22.4μg/mL时,SPIOs影响其存活和分化(P<0.05),在同一浓度条件下,Feridex和Resovist对NSCs的影响无显著性差异(P>0.05)。结论低浓度(<22.4μg/mL)的Feridex及Resovist对NSCs生物学特性无明显影响。

帕金森病大鼠模型定向移植Resovist标记骨髓基质干细胞的活体MR示踪

目的筛选并确定特定条件下行帕金森病（PD）大鼠模型纹状体定向移植骨髓基质干细胞（BMSCs）磁共振（MR）活体观察的最佳移植细胞数量及最佳观察时间。方法40只PD大鼠分为5组,移植Resovist标记BMSCs数量分别为1×105（第1组）、1.5×105（第2组）、2×105（第3组）、2.5×105（第4组）和对照组（第5组,注射生理盐水）,每组8只。运用FFE-T2WI序列在移植前、移植后1、4、8周对其行MR检查和阿朴吗啡旋转试验,测量并比较各组大鼠在各观察时间点脑内低信号区的体积大小,评估不同数量移植细胞的迁移情况,并观察其对PD大鼠的行为学治疗效果。移植细胞后12周,MR检查后处死大鼠行免疫组化检查。结果第1和第2组随时间延长MRI低信号区体积变小;第3和第4组第4周的低信号区体积大于第1周,但仅第3组差异有统计学意义（P=0.005）;第3组每分钟旋转次数降低幅度最大,与对照组差异有统计学意义（P=0.02）。结论与行为学试验相对应,2.0×105剂量组可作为活体MR观察的最佳剂量;立体定向移植BMSCs后1-4周可作为MR活体观察最佳时间。

Migration of Resovist-labeled neural stem cells towards focal rat cerebral ischemic regions as determined by in vivo tracking and magnetic resonance imaging

BACKGROUND:Resovist,a superparamagnetic iron oxide,can be used to label neural stem cells(NSCs).Magnetic resonance tracking of superparamagnetic iron oxide-labeled NSCs is a non-invasive technique to track transplanted NSCs following focal cerebral ischemia.OBJECTIVE:To observe survival and migration of transplanted NSCs in a rat model of focal ischemia/reperfusion using magnetic resonance imaging(MRI).DESIGN,TIME AND SETTING:An in vitro,in vivo,tracking study was performed at the Basic Laboratory of Harbin Medical University and the Room of MRI,Second Affiliated Hospital of Harbin Medical University,China from December 2006 to December 2009.MATERIALS:Resovist(Schering,Germany) and Achieva 1.5TMR imaging system(Philips,Amsterdam,the Netherlands) were utilized in the present study.METHODS:NSCs were harvested from brain tissues of neonatal Sprague Dawley rats and were labeled with Resovist(11.2 μg/mL and 5 × 105 cells/mL).A total of 15 adult,Sprague Dawley rats were randomly assigned to model(n = 9) and control(n = 6) groups.All rats were utilized to establish models of middle cerebral artery occlusion.Rats in the model group were subjected to Resovist-labeled NSCs transplantation by injection of cell suspension into both ventricles(5 μL/ventricle).Rats in the control group were treated with an equal volume of physiological saline.MAIN OUTCOME MEASURES:Immunocytochemistry,transmission electron microscopy,and Prussian blue staining were employed to observe whether cells phagocytized iron particles.In addition,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to measure viability and differentiation of NSCs labeled by various concentrations of Resovist.MRI was used to trace survival and migration of Resovist-labeled NSCs.RESULTS:Following Resovist and NSCs co-incubation,Prussian blue staining revealed iron particles in cells.In addition,staining was observed in daughter cells following cell division under transmission electron microscopy.A significant difference in viability and differentiation of NSCs in vitro labeled by various Resovist concentrations(2.8-11.2 μg/mL) was not detected(P > 0.05).Resovist(> 22.4 μg/mL) decreased cell viability and differentiation(P < 0.05).In vivo MRI of Resovist-labeled NSCs(11.2 μg/mL) revealed low signals.However,cells migrated towards the ischemic focus over time.CONCLUSION:Resovist,a magnetic probe,successfully labeled NSCs.MRI was successfully used to trace magnetic-labeled NSCs in vivo and allowed observation of cell survival and migration following transplantation.

Current status of superparamagnetic iron oxide contrast agents for liver magnetic resonance imaging

Five types of superparamagnetic iron oxide （SPIO）,i.e. Ferumoxides （Feridex？ Ⅳ, Berlex Laboratories）,Fe r u c a r b o t ra n （ Re s ov i s t？, B aye r H e a l t h c a re ） ,Ferumoxtran-10 （AMI-227 or Code-7227, Combidex？, AMAG Pharma; Sinerem？, Guerbet）, NC100150（Clariscan？, Nycomed,） and （VSOP C184, Ferropharm）have been designed and clinically tested as magneticresonance contrast agents. However, until nowResovist？ is current available in only a few countries.The other four agents have been stopped for furtherdevelopment or withdrawn from the market. AnotherSPIO agent Ferumoxytol （Feraheme） is approved forthe treatment of iron deficiency in adult chronic kidneydisease patients. Ferumoxytol is comprised of ironoxide particles surrounded by a carbohydrate coat, andit is being explored as a potential imaging approach forevaluating lymph nodes and certain liver tumors.

Magnetic labeling of primary murine monocytes using very small superparamagnetic iron oxide nanoparticles

Due to their very small size,nanoparticles can interact with all cells in the central nervous system.One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles(VSOP)that are citrate coated for electrostatic stabilization.To determine their influence on murine blood-derived monocytes,which easily enter the injured central nervous system,we applied VSOP and carboxydextran-coated superparamagnetic iron oxide nanoparticles(Resovist).We assessed their impact on the viability,cytokine,and chemokine secretion,as well as iron uptake of murine blood-derived monocytes.We found that(1)the monocytes accumulated VSOP and Resovist,(2)this uptake seemed to be nanoparticle-and time-dependent,(3)the decrease of monocytes viability was treatment-related,(4)VSOP and Resovist incubation did not alter cytokine homeostasis,and(5)overall a 6-hour treatment with 0.75 mM VSOP-R1 was probably sufficient to effectively label monocytes for future experiments.Since homeostasis is not altered,it is safe to label blood-derived monocles with VSOP.VSOP labeled monocytes can be used to study injured central nervous system sites further,for example with drug-carrying VSOP.