BMM tissue distribution assessed by MRI tests. MRI tests were used to track BMM migration. Feridex was administered to BMMs in vitro. After Feridex labeling, the BMMs were administered intravenously to immune-competent mice. Signal loss (darkened areas) is shown in the spleen (arrow) over time from 0, 3, 6, and 24 hours (A, B, C, and D, respectively) after adoptive transfer, demonstrating cell migration.