Aim: To develop a novel, magnetic resonance-based method for in vivo cell localization in the central nervous system (CNS) of the animals without sacrificing them.
Methods: Cells were labeled in vivo by intravenous injection of cell marker-specific antibodies covalently bound to ultrasmall superparamagnetic iron oxide particles (USPIO). This enabled the visualization of specific cell types by magnetic resonance microscopy (MRM).
Results: USPIOs covalently attached to antibodies affected the contrast in MRM scan, and their accumulation on cells manifested as signal weakening in T2*-weighted images or signal enhancement in T1-weighted images. With this method applied in the experimental autoimmune encephalomyelitis (EAE) murine multiple sclerosis (MS) model, CNS-infiltrating CD4+ T cells were easily visualized with cell-specific MRM.
Conclusion: MRM with targeted contrast materials can be used to localize CNS-infiltrating lymphocytes of interest. Due to its noninvasive character, this method could potentially be used in human MR imaging as well.