Angelica Polysaccharides Promotes Thrombopoiesis through the Phosphatidylinositol 3-Kinase/Akt Pathway.

Abstract

Angelica Polysaccharide is from the root of Radix Angelicae Sinensis (Chinese Danggui). Danggui has been used for centuries to treat blood-deficiency related diseases. The hematopoietic effect of Danggui may be related to its constituent, polysaccharide. However, the effects of angelica polysaccharide on hematopoietic stem/progenitor cells and megakaryocyte/platelet lineage have not been well studied. In this study, we specifically investigate the thrombopoietic effect of Angelica polysaccharide (APS) in a mouse model and its molecular mechanism. A myelosuppression mouse model (4-Gy-irradiated) was treated with APS (10 mg/kg/day) and thrombopoietin (TPO) (1 mg/kg/day). Peripheral blood cells from APS, TPO and vehicle-treated samples were counted on days 0, 7, 14 and 21. Then CFU assays were used to determine the effects of APS on the megakaryocytic progenitor cells and other lineages. Analyses of Annexin V, Caspase-3, and Mitochondrial Membrane Potential were conducted in megakaryocytic cell line M-07e. The effects of APS on cells treated with Ly294002, a Phosphatidylinositol 3-Kinse inhibitor and the effect of APS on the phosphorylation of AKT were also studied. APS as well as TPO significantly enhanced the recovery of platelet and WBC count, and bone marrow CFU-MK and CFU-GM formation (n=6). Morphological examination of bone marrows showed that APS treatment significantly increased the recovery of the megakaryocytic series. APS also increased the recovery of the body weight and organ weight (liver and spleen). However, APS didn't have a up-regulating effect on TPO production by a ELISA assay. We further analyzed the in vitro effect of APS on CFU-MK and CFU-GM formation. APS (50 ug/ml) enhanced TPO (50 ng/ml) -induced CFU-MK (p=0.06, n=4), and CFU-GM formation (p=0.032, n=6). However, APS alone (00 ug/ml) did not show significant effect on CFU-MK and CFU-GM proliferation (n=6). The effect of APS (1–500 ug/ml) on the growth of bone marrow stromal cells was further investigated using CFU-F (fibroblastoid) assay. APS (50 ug/ml) alone showed a promoting effect on CFU-F growth (p=0.049, n=3). APS (50 ug/ml) also significantly enhanced PDGF, bFGF and VEGF-induced CFU-F formation (n=4). Moreover, the anti-apoptotic effect of APS in M-07e cells was also demonstrated by using Annexin-V, Caspase-3, and JC-1 assays. Addition of Ly294002 alone increased the percentage of cells undergoing apoptosis. However, additional of APS to Ly294002-treated cells reversed the percentage of cells undergoing apoptosis. Furthermore, addition of APS significantly increased the phosphorylation of AKT. APS promotes thrombopoiesis in a mouse model. This effect is likely to be mediated by the PI3K/AKT pathway.