Figure 9a: (a, b) Graphs show donor cell activity migrates from the BM to the liver in control mice (b) but not in atherosclerotic apolipoprotein E–deficient mice (a). Percentages of whole-body activity, as determined with SPECT, are plotted against time after donor cell administration. In a, there is no significant difference in mean BM activity (43.5% vs 39.4%, P = .35) or mean liver activity (31.3% vs 34.1%, P = .13) between days 1 and 7. In b, there is a significant decrease in BM localization (35.8% vs 27.0%, P = .02) and an increase in liver localization (39.4% vs 44.9%, P = .03) between days 1 and 7, which indicate a net migration of donor cells between these organs. Mean spleen activity in control mice increased from day 1 to day 7; however, the increase was not significant (14.1% vs 19.0%, P = .08).