奈米鐵合金在細胞內外的磁感作用

Abstract

There are different kinds of ultrasmall superparamagnetic iron oxide (USPIO) used currently in the application of cell trafficking. Although the relaxivity of these iron oxide particles are well documented, the amount of cellular uptake and signal in MR system differs. The size of the iron oxide particles and the charge of the molecule accounts for only part of the character. Thus an efficient way to measure the uptake of the iron oxide particles is demanding. We demonstrated that it is an efficient way to evaluate the intracellular amount of the iron oxide particles by using mouse macrophage (Raw 264.7) as a cellular uptake system. Three different iron oxide particles were incubated with the Raw 264.7 for different time period. The uptake of these iron oxide particles was measured by flow cytometry, and microscopy. The amount of particle uptake measured from flow cytometry correlates well with the signal change determined by MR. Besides, the release of nitric oxide by Raw 264.7 is a indicator of inflammatory regulation. We tested USPIO about the release of the NO which revealed the USPIO has no influence on the regulation of inflammation. We conclude that measuring the uptake of iron oxides particles by using mice macrophage is an efficient way to evaluate the character of these iron oxide particles. Mouse macrophage cell line Raw 264.7 is a good in vitro model for studying USPIO, because the USPIO was uptake in vivo by reticuloendothelial system which resembles Raw 264.7. We tested three different kinds of iron oxide nanoparticles, USPIO201, USPIO202 (TANbead, Taiwan), and Resovist ® (Schering, Germany). USPIO 201 and USPIO 202 have Fe3O4 core with different coating. The size of the nanoparticle is ranged from 5~8 nm. USPIO-201 is positively charged while USPIO-202 is negatively charged. Resovsit ® is used widely as the magnetic resonance (MR) contrast medium especially for detecting hepatic tumors.