Effect of astragalus polysaccharide on Hematopoiesis and Thrombopoiesis In Vivo and In Vitro

Objective: Astragali Radix is a main component of DangGui BuXue Tang (DBT), a popular Chinese Medicine formula used for promotion of "blood production". Astragalus polysaccharide (APS) is the main active compound of Astragali Radix. Our previous studies have demonstrated the hematopoietic effect of DBT (Yang et al, J Ethnopharmacol 2009). The study is to investigate the effects of APS on hematopoiesis and thrombopoiesis in vivo and in vitro. Further, we determined the mechanism in this study. Methods: Irradiation-induced myelosuppression mice were divided into three groups of 6 subjects each. Three groups were treated with APS (10 mg/kg/day), thrombopoietin (TPO, 1μg/kg/day) and vehicle respectively. Peripheral blood cell counts from each group were then compared at different time-points. Colony-forming unit (CFU) assays were used to determine the mechanism of APS on the proliferation and differentiation of hematopoietic cells. Finally, using the HL-60 cell as model, we analyzed the cellular apoptosis progression with and without APS by Annexin V, Caspase 3 and JC-1. Results: APS enhanced platelets and red blood cells (RBC) of the myelosuppression mice recovery in vivo, except white blood cells (WBC). The platelet count in APS-treated mice were higher than that in control mice on day 7, day 14 and day 21( p< 0.05). Meanwhile, the RBC count in APS-treated mice was higher than that in control mice on day 21( p=0.003). Morphological examination showed that APS treatment significantly protected the hematopoietic cells from the irradiation-induced apoptosis . Moreover, APS promoted the formation of all lineages of CFU in vitro . Last, we test the expression of Annexin V, Caspase-3 and JC-1 via flow cytometry and found that APS significantly reduced cell apoptosis in HL-60 cells. Conclusions: APS can promote hematopoiesis and thrombopoiesis of irradiation mouse model in vivo and in vitro . APS promotes the proliferation of peripheral blood cells by promoting the proliferation of hematopoietic stem/progenitors and inhibiting apoptosis of hematopoietic cells.