Background:
Stanozolol and
danazol are widely used in the treatment of
aplastic anemia; however, their mechanisms of action are unclear. Methods: Bone marrow mononuclear cells from 10 patients newly diagnosed with
aplastic anemia and 10 healthy volunteers were collected and cultured together with
stanozolol,
danazol, or blank control separately for marrow colony assays. K562 cell lines that had been incubated with
stanozolol,
danazol, or blank control were tested for erythroid or megakaryocytic differentiation. Meanwhile, CB6F1/Crl mice were injected with 1 × 106 C57BL/6 donor-originated lymphocytes after irradiation with 5 Gy total body irradiation to establish a model for immune-mediated
bone marrow failure (
aplastic anemia mouse model). Mice with
aplastic anemia were treated with
cyclosporin A monotherapy,
cyclosporin A in combination with
stanozolol, and
cyclosporin A in combination with
danazol for 30 days. Peripheral blood cell counts once a week and bone marrow colony assays at the end of 1 month were performed. The proportion of T cell subsets, level of inflammatory factors,
erythropoietin, and
thrombopoietin were detected before and
after treatment. The levels of
erythropoietin receptors on bone marrow mononuclear cells
after treatment were tested using western blotting. Results: In the ex vivo experiments, the number of burst-forming units-erythroid; colony-forming units-granulocyte and macrophage; and colony-forming units-granulocyte, erythrocyte, monocyte, and megakaryocyte in the patients with
aplastic anemia were significantly lower than that in the normal controls (P < 0.05). However, the number of colonies and mean fluorescence intensity of CD235a or CD41 expression in the harvested cultured cells were not significantly different among the different treatment groups in the patients with
aplastic anemia, normal controls, and K562 cell lines. These results show that
stanozolol and
danazol produce no direct hematopoiesis-stimulating effects on progenitor cells. In the in vivo experiment, the mice with
aplastic anemia treated with
cyclosporin A and
danazol exhibited the most rapid recovery of platelet; the platelet count returned to normal levels after 3 weeks of treatment, which was at least 1 week earlier than in the other groups. In contrast, mice treated with
cyclosporin A and
stanozolol exhibited the highest
hemoglobin level at the end of treatment (P < 0.05). Bone marrow colony assays at 30 days showed that the number of burst-forming units-erythroid was the highest in mice treated with
cyclosporin A and
stanozolol, while the number of colony-forming units-granulocyte and macrophage was the highest in those treated with
cyclosporin A and
danazol. Compared to
cyclosporin A monotherapy, additional
stanozolol and
danazol can both increase the level of regulatory T cells and upregulate
interleukin-10, inhibiting the expression of
tumor necrosis factor-α (P < 0.05). However,
IL-2 was more effectively reduced by
danazol than by
stanozolol (P < 0.05). The
cyclosporin A- and
stanozolol-treated mice showed higher serum
erythropoietin (corrected by
hemoglobin level) and higher
erythropoietin receptor levels in bone marrow mononuclear cells than the other groups (P < 0.05). Conclusions: Neither
stanozolol nor
danazol directly stimulated hematopoiesis in vitro. However, in vivo,
stanozolol may exhibit an advantage in improving erythropoiesis, while
danazol may induce stronger effects on platelets. Both
danazol and
stanozolol exhibited immunosuppressive roles.
Stanozolol could enhance the secretion of
erythropoietin and expression of
erythropoietin receptor in bone marrow mononuclear cells.