Beneficial effect of minihepcidin peptide in a mouse model of PV. Mice affected by PV (Jak2^V617F/+ VAV-Cre double transgenic) were generated by transplantation of PV BM cells into lethally irradiated C57Bl/6 recipients. Four weeks post-BMT, when the phenotype was fully established, mice received SC injections of minihepcidin M009 (10 or 15 mg/kg) or vehicle twice a week for 3 weeks. At end point, hematological parameters such as HCT (A), RBC (B), and Hb (C), normally very high in PV mice, were significantly reduced (in a dose-dependent manner). Splenomegaly was also reduced (D). BM and spleen erythroid profiles were normalized (E), reflecting improved erythropoietic activity (as shown in the CD44-FSC [forward scatter] plots). Results represent mean ± SD; ****P < .0001, ***P < .001, **P < .01, and *P < .05. Analysis was performed using one-way ANOVA with Tukey multiple comparison adjustment.