Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Radiology, Nuclear Medicine & Medical Imaging, MRI, Photothrombotic lesion, Stroke, Iron oxide particles, SPIO, Stem cells, Inflammation, Macrophages, Microglia, IRON-OXIDE NANOPARTICLES, FOCAL CEREBRAL-ISCHEMIA, MAGNETIC-RESONANCE, BONE-MARROW, IN-VIVO, MACROPHAGE INFILTRATION, CONTRAST AGENTS, MOUSE-BRAIN, RAT-BRAIN, INFARCTION, Animals, Blood Vessels, Diffusion Magnetic Resonance Imaging, Disease Models, Animal, Fluorescent Antibody Technique, Green Fluorescent Proteins, Iron, Magnetic Resonance Imaging, Multipotent Stem Cells, Rats, Rats, Inbred F344, Stem Cell Transplantation, Thrombosis, 0606 Physiology, 1103 Clinical Sciences, Nuclear Medicine & Medical Imaging, 3202 Clinical sciences

Abstract:

PURPOSE: The aim of this study was to evaluate the specificity of magnetic resonance imaging (MRI) contrast in a photothrombotic (PT) stroke model with and without engraftment of superparamagnetic iron oxide (SPIO)-labeled stem cells. PROCEDURES: We monitored animals with PT stroke versus animals with PT stroke and stem cell engraftment by T(2)/T(2)*w MRI 4-8 h and 2, 4, 6/7 and 14 days after PT induction. Results were correlated with immunohistochemistry. RESULTS: T(2)*w MRI images showed hypointense contrast due to the accumulation of inflammatory cells and corresponding iron accumulation and glial scar formation in the border zone of the lesion, similar as what was observed for SPIO-labeled cells. Histological analysis was thus indispensable to distinguish between labeled transplanted cells and immune cells. CONCLUSION: These results raise caution regarding the non-invasive monitoring of SPIO-labeled transplanted stem cells by MRI in models that result in a strong inflammatory response.