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Figure 2. (+)-SW209415 promotes early hematopoietic homing, engraftment and recovery after bone marrow transplantation (BMT). (A) Lethally irradiated (11 Gy) 8-week old female C57/BL6J mice were transplanted with 107 CFSE-labeled total bone marrow cells and treated intraperitoneally with either vehicle or 2.5 mg/kg (+)-SW209415 immediately after irradiation, after BMT, and 8 hours (h) after BMT. Mice were sacrificed 16 h after the BMT and CFSE+ cells were measured in two femora + two tibiae/mouse. The graph shows mean values and Standard Error of Mean (SEM) (6 mice/arm). *Student t-test; P<0.05. (B) Lethally irradiated (11 Gy) 8-week old female C57/BL6J mice were transplanted with 200x103 total bone marrow cells and treated as in (A). The mice were sacrificed on day 12 after BMT. The spleens were harvested, fixed in Bouin solution, and the colonies counted (6 mice/arm). A second cohort of mice were sacrificed on day 12 and a single cell sus- pension prepared for SKL analysis via FACS (3 mice/arm). Representative photographs of day 12 spleens are shown on the left, with means and SEM of CFU-S and SKL numbers represented graphically on the right. *Student t-test; with a P<0.05. (C) Lethally irradiated (11 Gy) 8-week old female C57/BL6J mice were transplant- ed with 500x103 total bone marrow cells and treated intraperitoneally with either vehicle or 2.5 mg/kg (+)-SW209415 (twice daily). Peripheral blood counts were measured on days 8, 12, and 18 after BMT. The graph shows the mean values and SEM (13 mice/arm). *Student t-test; P<0.05.
15-PGDH inhibition in multiple models of murine BMT
Figure S3). We next examined the effects of (+)-SW209415 on splenic hematopoiesis following HSCT, where engraft- ment of individual HSC in the spleen can be assessed by their generation of macroscopic multilineage hematopoi- etic colonies termed CFU-S. On post-transplant day 12, (+)-SW209415-treated mice demonstrated a significant increase in total spleen colony counts (1.53-fold, P=0.003), an increased total spleen weight (Online Supplementary Figure S4), and a significantly higher number of splenic SKL cells (2.32-fold, P=0.02) (Figure 2B). We observed a similar 2.75-fold expansion of bone marrow SKL cells on day 18 in the same arm of (+)-SW209415-treated mice (P=0.0002). Thus (+)-SW209415 potentiates engraftment and expansion of donor hematopoietic cells in both bone marrow and spleen. Last, we examined the effect of (+)- SW209415 on the recovery of blood counts. (+)- SW209415-treated mice attained double the neutrophil
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counts of vehicle-treated control animals at each of post- HSCT days 8 (P<0.0001), 12 (P<0.0001), and 18 (P<0.0001) (Figure 2C). In addition, (+)-SW209415-treated mice demonstrated higher platelet counts on each of days 8 (P=0.005), 12 (P=0.06), and 18 (P=0.0005) and, in partic- ular, showed a significantly higher day 8 nadir count (98x109/L in (+)-SW209415 treated mice versus 73x109/L in vehicle-treated controls; P=0.005) (Online Supplementary Figure S5).
To further distinguish differential effects of (+)- SW209415 on early versus later steps in hematopoietic reconstitution, we compared the effects of giving (+)- SW209415 for only the first 7 days following bone mar- row transplantation (BMT) versus maintaining continuous dosing of (+)-SW209415 for 18 days. In this experiment mice that received continuous twice-daily doses of (+)- SW209415 attained neutrophil counts almost 3-fold high-
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