In vivo allogeneic homing using cfse labeled murine stem cells or surrogate secondary transplant

In order to characterize homing of allogeneic murine stem cells, a direct and a surrogate approach were utilized. First, 105 CFSE-labeled B6/SJL Lin-Sca1+ cells were injected in non-myeloablated BALB/c mice and fluorescent mononuclear cells were detected 1 and 6 hours after transplant by high-speed FACS analysis. In the surrogate approach, 108 B6/SJL whole BM cells were injected in lethally irradiated BALBc mice (10Gy) (5/time point). 1, 3 and 6 hours after transplant, BM was harvested and 1.1×107 cells were secondarily injected into myeloablated (8Gy) C5/BL6 mice (12/time point) with 1.1×107 competing C57/BL6 BM cells. Direct approach—CFSE positive cells were detected by FACS in BM 1 and 6 hours after injection. 11×106 events were analyzed in 4 mice. Surrogate approach—Secondary engrafted B6/JL Ly5.1 cells were detected in BM, spleen and thymus of myeloablated C57/BL6 recipient. Percentages of Ly5.1 cells over total Ly5.1 + Ly5.2 cells are shown in the figure. In conclusion, allogeneic homing was detectable from 1 to 6 hours after injection using either a direct approach with purified Lin-Sca1+ cells or a surrogate approach with whole bone marrow.