Systemically administered MV-infected BM-MSCs show early passive lung entrapment and subsequent relocalization to leukemic bone marrow. SCID mice with established Nalm 6 xenografts received intravenous injection with BM-MSCs infected with MV-luc. (A) Representative flow cytometry plots of murine bone marrow performed prior to administration of infected carrier cells, confirming the presence of CD19 (x-axis) and CD10 (y-axis) expressing leukemic populations. Gating was of live cells based on forward scatter and side scatter characteristics, with appropriate isotypes used as negative controls. (B) Representative bioluminescence images of SCID mice following systemic injection with MV-luc–infected BM-MSCs. Mice receiving PBS only were used as controls to account for background luminescence. For treatment group, N = 3.