A schedule of recombinant Mpl ligand highly effective at preventing lethal myelosuppression in mice given carboplatin and radiation

Danggui sini decoction ameliorates myelosuppression in animal model by upregulating Thrombopoietin expression

Danggui Sini decoction (DSD), a famous Chinese medicine, has been used therapeutically in various diseases. In this study, we tried to investigate whether and how DSD could ameliorate myelosuppression in an animal model, in which myelosuppression is induced by cyclophosphamide treatment. The myelosuppression model was established by intraperitoneal injection of 100 mg/kg cyclophosphamide in mice. Flow cytometry was used to assess cell numbers and evaluate the bone marrow cell cycle distribution. Spleen samples were collected, and the mRNA expression levels of thrombopoietin (TPO) and c-Mpl were analyzed by RT-PCR. Our results demonstrated that DSD could significantly elevate the level of bone marrow hematopoietic stem progenitor cells in myelosuppression mice model. DSD also accelerated cell proliferation by switching cell cycles from G0/G1 phase to S and G2/M phase. Moreover, DSD significantly elevated the mRNA expression level of TPO, but not c-Mpl in spleen. Overall, the present results indicated that DSD is a promising Chinese medicine that is highly potent to ameliorate myelosuppression induced by chemotherapy by upregulating TPO expression.

Suppressive effects of anthrax lethal toxin on megakaryopoiesis

Anthrax lethal toxin (LT) is a major virulence factor of Bacillus anthracis. LT challenge suppresses platelet counts and platelet function in mice, however, the mechanism responsible for thrombocytopenia remains unclear. LT inhibits cellular mitogen-activated protein kinases (MAPKs), which are vital pathways responsible for cell survival, differentiation, and maturation. One of the MAPKs, the MEK1/2-extracellular signal-regulated kinase pathway, is particularly important in megakaryopoiesis. This study evaluates the hypothesis that LT may suppress the progenitor cells of platelets, thereby inducing thrombocytopenic responses. Using cord blood-derived CD34(+) cells and mouse bone marrow mononuclear cells to perform in vitro differentiation, this work shows that LT suppresses megakaryopoiesis by reducing the survival of megakaryocytes. Thrombopoietin treatments can reduce thrombocytopenia, megakaryocytic suppression, and the quick onset of lethality in LT-challenged mice. These results suggest that megakaryocytic suppression is one of the mechanisms by which LT induces thrombocytopenia. These findings may provide new insights for developing feasible approaches against anthrax.

Short-term injection of antiapoptotic cytokine combinations soon after lethal gamma -irradiation promotes survival

Recovery from radiation-induced (RI) myelosuppression depends on hematopoietic stem and progenitor cell survival and the active proliferation/differentiation process, which requires early cytokine support. Single cytokine or late-acting growth factor therapy has proved to be inefficient in ensuring reconstitution after severe RI damage. This work was aimed at evaluating the in vivo survival effect of combinations of early-acting cytokines whose antiapoptotic activity has been demonstrated in vitro: stem cell factor (SCF [S]), FMS-like tyrosine kinase 3 ligand (FLT-3 ligand [F]), thrombopoietin (TPO [T]), interleukin-3 (IL-3 [3]), and stromal derived factor-1 (SDF-1). B6D2F1 mice underwent total body irradiation at 8 Gy cesium Cs 137 gamma radiation (ie, lethal dose 90% at 30 days) and were treated soon after irradiation, at 2 hours and at 24 hours, with recombinant murine cytokines, each given intraperitoneally at 50 microg/kg per injection. All treatments induced 30-day survival rates significantly higher than control (survival rate, 8.3%). 4F (SFT3) and 5F (4F + SDF-1) were the most efficient combinations (81.2% and 87.5%, respectively), which was better than 3F (SFT, 50%), TPO alone (58.3%), and SDF-1 alone (29.2%) and also better than 4F given at 10 microg/kg per injection (4F10, 45.8%) or as a 50 microg/kg single injection at 2 hours (4Fs, 62.5%). Despite delayed death occurring mainly from day 150 on and possible long-term hematopoiesis impairment, half the 30-day protective effects of 4F and 5F were preserved at 300 days. Our results show that short- and long-term survival after irradiation depends on appropriate multiple cytokine combinations and at optimal concentrations. The proposal is made that an emergency cytokine regimen could be applied to nuclear accident victims as part of longer cytokine treatment, cell therapy, or both.