The S1P/S1P1 axis regulates rapid AMD3100-induced mobilization of progenitor cells via enhanced SDF-1 release. (A) S1P ELISA plasma levels in PBS (control) and AMD3100 injected mice (single subcutaneous injection and evaluation after 5 minutes, 15 minutes or 1 hour) are shown. (B) S1P BM concentration in PBS (control) and AMD3100 injected mice (single subcutaneous injection and evaluation after 1 hour) are presented. (C-H) Mice were injected with PBS (control), FTY720 (single intraperitoneal injection and evaluation after 1.5 hours), AMD3100 (single subcutaneous injection and evaluation after 1 hour) or AMD3100+FTY720 (single intraperitoneal injection of FTY720 30 minutes before a single subcutaneous injection of AMD3100 and evaluation 1 hour after AMD3100 injection). The percentage of BM S1P1+/c-Kit+/Lin− cells (C) is shown. The numbers of WBCs (D), primitive SKL cells (E) Left, representative FACS plots of Lin− PB-MNC. The numbers in the top right quadrant of each plot represent SKL cells per 1 × 106 PB-MNC. (E) Right, total PB-MNC cell analysis and CFU-C (F) per milliliter blood are shown. Plasma SDF-1 ELISA levels (G) and the level of donor chimerism 1 month and 4 months after transplantation of whole pretreated blood (H) Left, representative FACS plots of total BM cells. The numbers in the top right quadrant of each plot represent % of engraftment. (H) Right, total engraftment analysis are presented. (I-M) WT and Sphk1 deficient mice (Sphk1 KO) were injected with PBS (control) or AMD3100 (single subcutaneous injection and evaluation after 1 hour). The numbers of WBCs (I), CFU-Cs (J), and primitive SKL cells (K) Left, representative FACS plots of Lin− PB-MNC. The numbers in the top right quadrant of each plot represent SKL cells per 1 × 106 PB-MNC. (K) Right, total PB-MNC cell analysis per milliliter of blood were analyzed. Plasma SDF-1 ELISA levels (L) and the level of donor chimerism 4 months after transplantation of whole pretreated blood (M) are shown. Indicated values are presented as mean ± SE in 3 independent experiments, a total of 6 mice in each group. Repopulation experiments were performed with a total of 4-7 mice per each group (*P < .05, **P < .01).