Real-time in vivo cellular imaging of graft-versus-host disease and its reaction to immunomodulatory reagents

Abstract Visualizing the in vivo dynamics of individual donor cells after allogeneic hematopoietic stem cell transplantation (HSCT) will enable deeper understanding of the process of graft- versus -host disease (GVHD) and graft- versus -leukemia (GVL). In this study, using non-invasive in vivo fluorescence imaging of the ear pinna, we successfully visualized green fluorescent protein (GFP) donor cells at the single cell level in the skin. This imaging model enabled visualization of the movement of GFP cells into blood vessels in real time after allogeneic HSCT. At day 1, a few donor cells were detected, and the movement of donor cells in blood vessels was readily observed at day 4. Early donor cell infiltration into non-lymphoid tissue was increased by treatment with croton oil, as an inflammatory reagent. Treatment with dexamethasone, as an anti-inflammatory reagent, suppressed donor cell infiltration. The in vivo cellular fluorescence imaging model described here is a very useful tool for monitoring individual donor cells in real-time and for exploring immunomodulatory reagents for allogeneic HSCT, as well as for understanding the mechanism of GVHD.