In situ labeling and magnetic resonance imaging of transplanted human hepatic stem cells.

PURPOSE: The purpose is to address the problem in magnetic resonance imaging (MRI) of contrast agent dilution. PROCEDURES: In situ magnetic labeling of cells and MRI were used to assess distribution and growth of human hepatic stem cells (hHpSCs) transplanted into severe combined immunodeficiency (SCID)/non-obese diabetic (NOD) mice. It was done with commercially available magnetic microbeads coupled to an antibody to a surface antigen, epithelial cell adhesion molecule (EpCAM), uniquely expressed in the liver by hepatic progenitors. RESULTS: We validated the microbead connection to cells and related MRI data to optical microscopy observations in order to develop a means to quantitatively estimate cell numbers in the aggregates detected. Cell counts of hHpSCs at different times post-transplantation revealed quantifiable evidence of cell engraftment and expansion. CONCLUSIONS: This magnetic labeling methodology can be used with any antibody coupled to a magnetic particle to target any surface antigen that distinguishes transplanted cells from host cells, thus facilitating studies that define methods and strategies for clinical cell therapy programs.