Oestrogen-deficiency inducing haematopoiesis dysfunction via reduction in haematopoietic stem cells and haematopoietic growth factors in rats.

Haematopoiesis is a self-renewing and multi-directional differentiation process of haematopoietic stem cells (HSCs), which is modulated very precisely by the haematopoietic microenvironment in bone marrow. Our previous study has demonstrated that oestrogen-deficiency leads to haematopoiesis dysfunction which manifests as a decrease in haematopoietic tissues and an increase in adipose tissues in bone marrow. However, the mechanism involved in the oestrogen-deficiency effects on haematopoiesis dysfunction is not completely understood. In this study, we established an oestrogen-deficiency rat model by ovariectomy (OVX group). Haematopoiesis was evaluated at the 12th, 16th, 20th, 24th and 28th weeks after operation in the OVX group and its control (Sham group) by pathological examination; the number and function of HSCs were evaluated by flow cytometry analysis and colony-forming assay respectively. Haematopoietic growth factors levels including granulocyte/macrophage-colony-stimulating factor (GM-CSF), stem cell factor (SCF) and interleukin-3 (IL-3) were examined by ELISA kits at different time points. We found that in the OVX group, haematopoiesis dysfunction in bone marrow was observed (P < 0.05) from the 12th week when compared with the Sham group, and extramedullary haematopoiesis began to appear in the liver and spleen from the 16th week. The number of HSCs and colony-forming units-granulocyte/macrophage (CFUs-GM) in bone marrow was reduced significantly (P < 0.05) from the 20th and 16th week respectively. Furthermore, GM-CSF, SCF and IL-3 in the OVX group decreased significantly (P < 0.05) since the 12th, 16th and 24th week respectively. Taken together, these results suggested that oestrogen is required for normal haematopoiesis. Oestrogen-deficiency inducing haematopoiesis dysfunction may be via reduction in HSCs and haematopoietic growth factors at a late stage.