Astragalus polysaccharide has a protective effect on hematopoiesis in an irradiated mouse model and decreases apoptosis in megakaryocytes.

Huangqi, the dried root of Radix Astragali, is an essential herb in Traditional Chinese Medicine and has been used to promote hematopoiesis for centuries. Astragalus polysaccharide (ASPS), the bioactive compound of Huangqi, serves a crucial role in hematopoiesis. The aim of the present study was to investigate the hematopoietic effects, in particular the thrombopoietic effects, and the molecular mechanisms of ASPS using an irradiation-induced myelosuppressive mouse model. Colony-forming unit assays, flow cytometric analysis of apoptosis, ELISAs, Giemsa staining and western blotting were performed to determine the hematopoietic and anti-apoptotic effects of ASPS. The results demonstrated that ASPS enhanced the recovery of red blood cells at day 21 following treatment, as well as platelets and white blood cells at day 14. In addition, ASPS promoted colony formation in all lineages (megakaryocytes, granulocyte monocytes, erythroid cells and fibroblasts). The morphological study of the bone marrow demonstrated that tri-lineage hematopoiesis was preserved in the ASPS- and thrombopoietin (TPO)-treated groups compared with the control group. The overall cellularity (mean total cell count/area) of the ASPS-treated group was similar to that of the TPO-treated group. Additionally, in vitro experiments indicated that treatment with 100 mu g/ml ASPS exhibited the maximum effect on colony formation. ASPS attenuated cell apoptosis in megakaryocytic cells via inhibiting the mitochondrial caspase-3 signaling pathway. In conclusion, ASPS promoted hematopoiesis in irradiated myelosuppressive mice possibly via enhancing hematopoietic stem/progenitor cell proliferation and inhibiting megakaryocytes apoptosis.