Effectiveness of micron-sized superparamagnetic iron oxide particles as markers for detection of migration of bone marrow-derived mesenchymal stromal cells in a stroke model.

PURPOSE: To evaluate the feasibility of using micron-sized superparamagnetic iron oxide particles (MPIOs) as an effective labeling agent for monitoring bone marrow-derived mesenchymal stromal cell (BMSC) migration in the brain using magnetic resonance imaging (MRI) in a rat model of stroke and whether the accumulation of MPIO-labeled BMSCs can be differentiated from the accumulation of free MPIO particles or hemoglobin breakdown at a site of neuronal damage.
MATERIALS AND METHODS: In this study BMSCs were labeled with iron oxide and their pattern of migration following intravenous injection in a rat stroke model was monitored using a clinical MRI system followed by standard histopathology. The migration pattern was compared between intravenous injection of BMSCs alone, BMSCs labeled with MPIOs, and MPIO particles alone.
RESULTS: The results demonstrated that while MRI was highly sensitive in the detection of iron oxide particle-containing cells in areas of neuronal ischemia, the true origin of cells containing iron oxide particles remains ambiguous. Therefore, detection of iron particles may not be a suitable strategy for the detection of BMSCs in the brain in a stroke model.
CONCLUSION: This study suggests that the use of MPIOs as labeling agents are insufficient to conclusively determine the localization of iron within cells in regions of neuronal ischemia and hemorrhage.