RESUMEN
<p><b>OBJECTIVE</b>To explore the feasibility and fluorescence characteristics of CFSE negative staining for in vivo cell imaging of super paramagnetic iron oxide nanoparticles (SPIO) phagocytosed by mouse mononuclear macrophage leukemia cells-RAW264.7.</p><p><b>METHODS</b>After labeled with SPIO, the RAW264.7 macrophages were stained with Prussian blue stain and CFSE fluorescence negative stain step by step. Furthermore, trypan blue staining was used to evaluate cell viability of cells which stained with CFSE. At last, laser scanning confocal microscope was used to measure SPIO in cells through CFSE fluorescence negative stain method.</p><p><b>RESULTS</b>SPIO within RAW264.7 macrophages showed blue in Prussian's blue staining, while showed negative area in CFSE negative staining. Good consistencies between Prussian's blue staining and CFSE negative staining were observed. In addition, RAW264.7 macrophages showed high viability after SPIO/CFSE dual-labeled method, proved by typan stain.</p><p><b>CONCLUSION</b>The CFSE fluorescence negative staining may be used for detecting SPIO that phagocytosed by RAW264.7 macrophages and it is showed good consistency that confirmed one another when compared to classic Prussian' blue staining.</p>