Abstract: Objective: To investigate whether CM-DiI labeled BMSCs could be detected in central nervous system (CNS) of MS rat models and how they migrated. Methods BMSCs were obtained and subsequently cultured with whole bone marrow cell culture method. CM-DiI solution was used to label BMSCs in vitro and tagged cells were transplanted into EAE rats by intravenous injection through caudal vein. Tissue sections were performed and were detected under fluorescence microscope. Results CM-DiI labeled BMSCs mostly distributed around perivascular and subpial areas of spinal cord , cerebrum and cerebellum, showing round or oval shape during peak period. Cells failed to migrate into parenchyma in EAE rats. The duration is long than 2 weeks after implantation cells could be detected clearly. Conclusions CM-DiI is a good choice for BMSCs labeling and tracing. Labeled cells keep their morphology in vivo and mainly locate around vessels and subpial areas, less migrating into parenchyma of CNS.

Key words: CM-DiI, Bone marrow stem cells (BMSC), Experimental autoimmune encephalomyelitis (EAE, Tracing