The hematopoietic activity of EPO is unfavorable to the treatment of bleomycin-induced pulmonary fibrosis in mice.

The main function of erythropoietin (EPO) is to promote hematopoiesis and improve anemia. In addition, EPO also has many non-hematopoietic effects such as anti-inflammation, anti-apoptosis and anti-oxidation. To achieve the protective effects, large doses of EPO are required, so the probability of side effects increases. Previous studies have revealed that EPO can improve pulmonary fibrosis in mice, but it has not been clarified whether the hematopoiesis of EPO contributes to amelioration of pulmonary fibrosis and whether EPO improves overall mortality. Our results show that EPO decreases hydroxyproline content, α-sma and col-1 protein levels in mice with bleomycin-induced pulmonary fibrosis. However, compared with the control group, the weight loss and mortality rate of the EPO group were not improved, while the number of red blood cells (RBCs), hemoglobin (Hb), red cell width distribution-coefficient of variation (RDW-CV) and hematocrit (HCT) were significantly higher. Furthermore, we observed massive thrombosis in the lung of EPO treated lung fibrosis mice but not in control mice. Therefore, our results show that in the condition of lung fibrosis, the hematopoietic activity of exogenous EPO is not conducive to its tissue protective effect.