Magnetic resonance imaging (MRI) scans were performed in myelin- deficient animals in which magnetically labeled progenitor oligodendrocytes were implanted into the spinal cord. Three-dimensional MR microscopy (MRM) was performed ex vivo on the spinal cords with 78 micron isotropic resolution at 4.7 Tesla. MR microscopy showed extensive migration (up to 8.4 mm) of magnetically labeled grafted cells, particularly in the area of the dorsal column. MR images were correlated with histopathologic staining for iron, myelin, astrocytes, and microglia. Both the Prussian blue and myelin staining closely matched the area of contrast enhancement seen on the MR images (Bulte et al PNAS 1999; 96:15256-61). Magnetically labeled precursor oligodendrocytes have also been implanted in the brains of dysmyelinated rats and cell proliferation and migration has also been noted at clinically relevant magnetic resonance imaging 1.5 Tesla units which indicates the possibility of in vivo monitoring the migration and function of neural transplanted stem cells.Serial MRI studies performed in the marmoset model experimental autoimmune encephalomyelitis (EAE) are being used as part pre-clinical evaluation of new therapies for multiple sclerosis (Jordan, et al., American Journal of Neuroradiology 1999;20:965-76). The serial MRI studies have demonstrated week to week changes in the number and distribution of EAE lesions. MRI stereotactic directed biopsy techniques have been perfected that will allow us to biopsy EAE lesion for histopathologic and microarray analysis to reveal the immunologic, cellular, and biochemical microenvironment of the EAE lesion.
